First batch of null -> isEmpty() checks.

I most likely still missed a ton of checks...

src/main/java/appeng/block/crafting/ItemCraftingStorage.java

@@ -39,7 +39,7 @@ public class ItemCraftingStorage extends AEBaseItemBlock
 	@Override
 	public ItemStack getContainerItem( final ItemStack itemStack )
 	{
-		return AEApi.instance().definitions().blocks().craftingUnit().maybeStack( 1 ).orElse( null );
+		return AEApi.instance().definitions().blocks().craftingUnit().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 	}
 
 	@Override

src/main/java/appeng/block/qnb/QnbFormedBakedModel.java

@@ -18,6 +18,7 @@ import net.minecraft.client.renderer.block.model.ItemCameraTransforms;
 import net.minecraft.client.renderer.block.model.ItemOverrideList;
 import net.minecraft.client.renderer.texture.TextureAtlasSprite;
 import net.minecraft.client.renderer.vertex.VertexFormat;
+import net.minecraft.item.ItemStack;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.ResourceLocation;
 import net.minecraftforge.common.property.IExtendedBlockState;

src/main/java/appeng/client/gui/AEBaseGui.java

@@ -92,7 +92,7 @@ public abstract class AEBaseGui extends GuiContainer
 	private GuiScrollbar myScrollBar = null;
 	private boolean disableShiftClick = false;
 	private Stopwatch dbl_clickTimer = Stopwatch.createStarted();
-	private ItemStack dbl_whichItem;
+	private ItemStack dbl_whichItem = ItemStack.EMPTY;
 	private Slot bl_clicked;
 	private boolean subGui;
 
@@ -304,7 +304,7 @@ public abstract class AEBaseGui extends GuiContainer
 			this.getScrollBar().click( this, x - this.guiLeft, y - this.guiTop );
 		}
 
-		if( slot instanceof SlotFake && itemstack != null )
+		if( slot instanceof SlotFake && !itemstack.isEmpty() )
 		{
 			this.drag_click.add( slot );
 			if( this.drag_click.size() > 1 )
@@ -499,21 +499,21 @@ public abstract class AEBaseGui extends GuiContainer
 		{
 			this.disableShiftClick = true;
 
-			if( this.dbl_whichItem == null || this.bl_clicked != slot || this.dbl_clickTimer.elapsed( TimeUnit.MILLISECONDS ) > 150 )
+			if( this.dbl_whichItem.isEmpty() || this.bl_clicked != slot || this.dbl_clickTimer.elapsed( TimeUnit.MILLISECONDS ) > 150 )
 			{
 				// some simple double click logic.
 				this.bl_clicked = slot;
 				this.dbl_clickTimer = Stopwatch.createStarted();
 				if( slot != null )
 				{
-					this.dbl_whichItem = slot.getHasStack() ? slot.getStack().copy() : null;
+					this.dbl_whichItem = slot.getHasStack() ? slot.getStack().copy() : ItemStack.EMPTY;
 				}
 				else
 				{
-					this.dbl_whichItem = null;
+					this.dbl_whichItem = ItemStack.EMPTY;
 				}
 			}
-			else if( this.dbl_whichItem != null )
+			else if( !this.dbl_whichItem.isEmpty() )
 			{
 				// a replica of the weird broken vanilla feature.
 
@@ -540,7 +540,7 @@ public abstract class AEBaseGui extends GuiContainer
 	{
 		final Slot theSlot = this.getSlotUnderMouse();
 
-		if( this.mc.player.inventory.getItemStack() == null && theSlot != null )
+		if( this.mc.player.inventory.getItemStack().isEmpty() && theSlot != null )
 		{
 			for( int j = 0; j < 9; ++j )
 			{
@@ -728,7 +728,7 @@ public abstract class AEBaseGui extends GuiContainer
 			try
 			{
 				final ItemStack is = s.getStack();
-				if( s instanceof AppEngSlot && ( ( (AppEngSlot) s ).renderIconWithItem() || is == null ) && ( ( (AppEngSlot) s ).shouldDisplay() ) )
+				if( s instanceof AppEngSlot && ( ( (AppEngSlot) s ).renderIconWithItem() || is.isEmpty() ) && ( ( (AppEngSlot) s ).shouldDisplay() ) )
 				{
 					final AppEngSlot aes = (AppEngSlot) s;
 					if( aes.getIcon() >= 0 )
@@ -776,7 +776,7 @@ public abstract class AEBaseGui extends GuiContainer
 					}
 				}
 
-				if( is != null && s instanceof AppEngSlot )
+				if( !is.isEmpty() && s instanceof AppEngSlot )
 				{
 					if( ( (AppEngSlot) s ).getIsValid() == hasCalculatedValidness.NotAvailable )
 					{

src/main/java/appeng/client/gui/AEBaseMEGui.java

@@ -44,7 +44,7 @@ public abstract class AEBaseMEGui extends AEBaseGui
 
 	public List<String> handleItemTooltip( final ItemStack stack, final int mouseX, final int mouseY, final List<String> currentToolTip )
 	{
-		if( stack != null )
+		if( !stack.isEmpty() )
 		{
 			final Slot s = this.getSlot( mouseX, mouseY );
 			if( s instanceof SlotME )
@@ -101,7 +101,7 @@ public abstract class AEBaseMEGui extends AEBaseGui
 	protected void renderToolTip( final ItemStack stack, final int x, final int y )
 	{
 		final Slot s = this.getSlot( x, y );
-		if( s instanceof SlotME && stack != null )
+		if( s instanceof SlotME && !stack.isEmpty() )
 		{
 			final int BigNumber = AEConfig.instance().useTerminalUseLargeFont() ? 999 : 9999;
 

src/main/java/appeng/client/gui/Size1Slot.java

@@ -33,7 +33,7 @@ class Size1Slot extends Slot
 	public ItemStack getStack()
 	{
 		ItemStack orgStack = delegate.getStack();
-		if( orgStack != null )
+		if( !orgStack.isEmpty() )
 		{
 			ItemStack modifiedStack = orgStack.copy();
 			modifiedStack.setCount( 1 );

src/main/java/appeng/client/gui/implementations/GuiCellWorkbench.java

@@ -140,7 +140,7 @@ public class GuiCellWorkbench extends GuiUpgradeable
 		for( int x = 0; x < inv.getSizeInventory(); x++ )
 		{
 			final ItemStack is = inv.getStackInSlot( x );
-			if( is != null && is.getItem() instanceof IUpgradeModule )
+			if( !is.isEmpty() && is.getItem() instanceof IUpgradeModule )
 			{
 				if( ( (IUpgradeModule) is.getItem() ).getType( is ) == Upgrades.FUZZY )
 				{

src/main/java/appeng/client/gui/implementations/GuiCraftAmount.java

@@ -107,23 +107,23 @@ public class GuiCraftAmount extends AEBaseGui
 
 		if( target instanceof PartTerminal )
 		{
-			myIcon = parts.terminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.terminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 			this.originalGui = GuiBridge.GUI_ME;
 		}
 
 		if( target instanceof PartCraftingTerminal )
 		{
-			myIcon = parts.craftingTerminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.craftingTerminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 			this.originalGui = GuiBridge.GUI_CRAFTING_TERMINAL;
 		}
 
 		if( target instanceof PartPatternTerminal )
 		{
-			myIcon = parts.patternTerminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.patternTerminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 			this.originalGui = GuiBridge.GUI_PATTERN_TERMINAL;
 		}
 
-		if( this.originalGui != null && myIcon != null )
+		if( this.originalGui != null && !myIcon.isEmpty() )
 		{
 			this.buttonList.add( this.originalGuiBtn = new GuiTabButton( this.guiLeft + 154, this.guiTop, myIcon, myIcon.getDisplayName(), this.itemRender ) );
 		}

src/main/java/appeng/client/gui/implementations/GuiCraftingStatus.java

@@ -57,7 +57,7 @@ public class GuiCraftingStatus extends GuiCraftingCPU
 
 	private GuiTabButton originalGuiBtn;
 	private GuiBridge originalGui;
-	private ItemStack myIcon = null;
+	private ItemStack myIcon = ItemStack.EMPTY;
 
 	public GuiCraftingStatus( final InventoryPlayer inventoryPlayer, final ITerminalHost te )
 	{
@@ -70,28 +70,28 @@ public class GuiCraftingStatus extends GuiCraftingCPU
 
 		if( target instanceof WirelessTerminalGuiObject )
 		{
-			myIcon = definitions.items().wirelessTerminal().maybeStack( 1 ).orElse( null );
+			myIcon = definitions.items().wirelessTerminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			this.originalGui = GuiBridge.GUI_WIRELESS_TERM;
 		}
 
 		if( target instanceof PartTerminal )
 		{
-			myIcon = parts.terminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.terminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			this.originalGui = GuiBridge.GUI_ME;
 		}
 
 		if( target instanceof PartCraftingTerminal )
 		{
-			myIcon = parts.craftingTerminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.craftingTerminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			this.originalGui = GuiBridge.GUI_CRAFTING_TERMINAL;
 		}
 
 		if( target instanceof PartPatternTerminal )
 		{
-			myIcon = parts.patternTerminal().maybeStack( 1 ).orElse( null );
+			myIcon = parts.patternTerminal().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			this.originalGui = GuiBridge.GUI_PATTERN_TERMINAL;
 		}
@@ -131,7 +131,7 @@ public class GuiCraftingStatus extends GuiCraftingCPU
 		// selectCPU.enabled = false;
 		this.buttonList.add( this.selectCPU );
 
-		if( this.myIcon != null )
+		if( !this.myIcon.isEmpty() )
 		{
 			this.buttonList.add( this.originalGuiBtn = new GuiTabButton( this.guiLeft + 213, this.guiTop - 4, this.myIcon, this.myIcon.getDisplayName(), this.itemRender ) );
 			this.originalGuiBtn.setHideEdge( 13 );

src/main/java/appeng/client/me/ItemRepo.java

@@ -84,7 +84,7 @@ public class ItemRepo
 
 		if( idx >= this.dsp.size() )
 		{
-			return null;
+			return ItemStack.EMPTY;
 		}
 		return this.dsp.get( idx );
 	}

src/main/java/appeng/client/me/SlotDisconnected.java

@@ -63,11 +63,11 @@ public class SlotDisconnected extends AppEngSlot
 		if( Platform.isClient() )
 		{
 			final ItemStack is = super.getStack();
-			if( is != null && is.getItem() instanceof ItemEncodedPattern )
+			if( !is.isEmpty() && is.getItem() instanceof ItemEncodedPattern )
 			{
 				final ItemEncodedPattern iep = (ItemEncodedPattern) is.getItem();
 				final ItemStack out = iep.getOutput( is );
-				if( out != null )
+				if( !out.isEmpty() )
 				{
 					return out;
 				}

src/main/java/appeng/client/me/SlotME.java

@@ -60,7 +60,7 @@ public class SlotME extends Slot
 		{
 			return this.mySlot.getStack();
 		}
-		return null;
+		return ItemStack.EMPTY;
 	}
 
 	@Override
@@ -68,7 +68,7 @@ public class SlotME extends Slot
 	{
 		if( this.mySlot.hasPower() )
 		{
-			return this.getStack() != null;
+			return !this.getStack().isEmpty();
 		}
 		return false;
 	}
@@ -88,7 +88,7 @@ public class SlotME extends Slot
 	@Override
 	public ItemStack decrStackSize( final int par1 )
 	{
-		return null;
+		return ItemStack.EMPTY;
 	}
 
 	@Override

src/main/java/appeng/client/render/StackSizeRenderer.java

@@ -44,7 +44,7 @@ public class StackSizeRenderer
 
 	public void renderStackSize( FontRenderer fontRenderer, IAEItemStack aeStack, ItemStack is, int xPos, int yPos )
 	{
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			final float scaleFactor = AEConfig.instance().useTerminalUseLargeFont() ? 0.85f : 0.5f;
 			final float inverseScaleFactor = 1.0f / scaleFactor;

src/main/java/appeng/client/render/tesr/InscriberTESR.java

@@ -132,15 +132,15 @@ public class InscriberTESR extends TileEntitySpecialRenderer<TileInscriber>
 		GlStateManager.color( 1.0F, 1.0F, 1.0F, 1.0F );
 
 		int items = 0;
-		if( tile.getStackInSlot( 0 ) != null )
+		if( !tile.getStackInSlot( 0 ).isEmpty() )
 		{
 			items++;
 		}
-		if( tile.getStackInSlot( 1 ) != null )
+		if( !tile.getStackInSlot( 1 ).isEmpty() )
 		{
 			items++;
 		}
-		if( tile.getStackInSlot( 2 ) != null )
+		if( !tile.getStackInSlot( 2 ).isEmpty() )
 		{
 			items++;
 		}
@@ -151,7 +151,7 @@ public class InscriberTESR extends TileEntitySpecialRenderer<TileInscriber>
 		{
 			ItemStack is = tile.getStackInSlot( 3 );
 
-			if( is == null )
+			if( is.isEmpty() )
 			{
 				final IInscriberRecipe ir = tile.getTask();
 				if( ir != null )
@@ -177,7 +177,7 @@ public class InscriberTESR extends TileEntitySpecialRenderer<TileInscriber>
 
 	private void renderItem( ItemStack sis, final float o, final AEBaseTile tile, final VertexBuffer tess, final double x, final double y, final double z )
 	{
-		if( sis != null )
+		if( !sis.isEmpty() )
 		{
 			sis = sis.copy();
 

src/main/java/appeng/container/AEBaseContainer.java

@@ -224,8 +224,8 @@ public abstract class AEBaseContainer extends Container
 		// client doesn't need to re-send, makes for lower overhead rapid packets.
 		if( Platform.isClient() )
 		{
-			final ItemStack a = stack == null ? null : stack.getItemStack();
+			final ItemStack a = stack == null ? ItemStack.EMPTY : stack.getItemStack();
-			final ItemStack b = this.clientRequestedTargetItem == null ? null : this.clientRequestedTargetItem.getItemStack();
+			final ItemStack b = this.clientRequestedTargetItem == null ? ItemStack.EMPTY : this.clientRequestedTargetItem.getItemStack();
 
 			if( Platform.itemComparisons().isSameItem( a, b ) )
 			{
@@ -483,7 +483,7 @@ public abstract class AEBaseContainer extends Container
 		{
 			ItemStack tis = clickSlot.getStack();
 
-			if( tis == null )
+			if( tis.isEmpty() )
 			{
 				return ItemStack.EMPTY;
 			}
@@ -533,7 +533,7 @@ public abstract class AEBaseContainer extends Container
 			 */
 			if( selectedSlots.isEmpty() && clickSlot.isPlayerSide() )
 			{
-				if( tis != null )
+				if( !tis.isEmpty() )
 				{
 					// target slots in the container...
 					for( final Object inventorySlot : this.inventorySlots )
@@ -547,7 +547,7 @@ public abstract class AEBaseContainer extends Container
 							{
 								break;
 							}
-							else if( destination == null )
+							else if( destination.isEmpty() )
 							{
 								cs.putStack( tis.copy() );
 								cs.onSlotChanged();
@@ -559,7 +559,7 @@ public abstract class AEBaseContainer extends Container
 				}
 			}
 
-			if( tis != null )
+			if( !tis.isEmpty() )
 			{
 				// find partials..
 				for( final Slot d : selectedSlots )
@@ -595,7 +595,7 @@ public abstract class AEBaseContainer extends Container
 
 								if( tis.getCount() <= 0 )
 								{
-									clickSlot.putStack( null );
+									clickSlot.putStack( ItemStack.EMPTY );
 									d.onSlotChanged();
 
 									// if ( hasMETiles ) updateClient();
@@ -647,7 +647,7 @@ public abstract class AEBaseContainer extends Container
 
 								if( tis.getCount() <= 0 )
 								{
-									clickSlot.putStack( null );
+									clickSlot.putStack( ItemStack.EMPTY );
 									d.onSlotChanged();
 
 									// if ( worldEntity != null )
@@ -683,7 +683,7 @@ public abstract class AEBaseContainer extends Container
 
 							if( tis.getCount() <= 0 )
 							{
-								clickSlot.putStack( null );
+								clickSlot.putStack( ItemStack.EMPTY );
 								d.onSlotChanged();
 
 								// if ( worldEntity != null )
@@ -703,7 +703,7 @@ public abstract class AEBaseContainer extends Container
 				}
 			}
 
-			clickSlot.putStack( tis != null ? tis.copy() : null );
+			clickSlot.putStack( !tis.isEmpty() ? tis.copy() : ItemStack.EMPTY );
 		}
 
 		this.updateSlot( clickSlot );
@@ -766,9 +766,9 @@ public abstract class AEBaseContainer extends Container
 				{
 					case PICKUP_OR_SET_DOWN:
 
-						if( hand == null )
+						if( hand.isEmpty() )
 						{
-							s.putStack( null );
+							s.putStack( ItemStack.EMPTY );
 						}
 						else
 						{
@@ -778,7 +778,7 @@ public abstract class AEBaseContainer extends Container
 						break;
 					case PLACE_SINGLE:
 
-						if( hand != null )
+						if( !hand.isEmpty() )
 						{
 							final ItemStack is = hand.copy();
 							is.setCount( 1 );
@@ -789,9 +789,9 @@ public abstract class AEBaseContainer extends Container
 					case SPLIT_OR_PLACE_SINGLE:
 
 						ItemStack is = s.getStack();
-						if( is != null )
+						if( !is.isEmpty() )
 						{
-							if( hand == null )
+							if( hand.isEmpty() )
 							{
 								is.setCount( Math.max( 1, is.getCount() - 1 ) );
 							}
@@ -807,7 +807,7 @@ public abstract class AEBaseContainer extends Container
 
 							s.putStack( is );
 						}
-						else if( hand != null )
+						else if( !hand.isEmpty() )
 						{
 							is = hand.copy();
 							is.setCount( 1 );
@@ -866,7 +866,7 @@ public abstract class AEBaseContainer extends Container
 					myItem.setCount( (int) ais.getStackSize() );
 					myItem = adp.simulateAdd( myItem );
 
-					if( myItem != null )
+					if( !myItem.isEmpty() )
 					{
 						ais.setStackSize( ais.getStackSize() - myItem.getCount() );
 					}
@@ -887,7 +887,7 @@ public abstract class AEBaseContainer extends Container
 				final int releaseQty = 1;
 				final ItemStack isg = player.inventory.getItemStack();
 
-				if( isg != null && releaseQty > 0 )
+				if( !isg.isEmpty() && releaseQty > 0 )
 				{
 					IAEItemStack ais = AEApi.instance().storage().createItemStack( isg );
 					ais.setStackSize( 1 );
@@ -899,7 +899,7 @@ public abstract class AEBaseContainer extends Container
 						final InventoryAdaptor ia = new AdaptorPlayerHand( player );
 
 						final ItemStack fail = ia.removeItems( 1, extracted.getItemStack(), null );
-						if( fail == null )
+						if( fail.isEmpty() )
 						{
 							this.getCellInventory().extractItems( extracted, Actionable.MODULATE, this.getActionSource() );
 						}
@@ -921,7 +921,7 @@ public abstract class AEBaseContainer extends Container
 					int liftQty = 1;
 					final ItemStack item = player.inventory.getItemStack();
 
-					if( item != null )
+					if( !item.isEmpty() )
 					{
 						if( item.getCount() >= item.getMaxStackSize() )
 						{
@@ -943,7 +943,7 @@ public abstract class AEBaseContainer extends Container
 							final InventoryAdaptor ia = new AdaptorPlayerHand( player );
 
 							final ItemStack fail = ia.addItems( ais.getItemStack() );
-							if( fail != null )
+							if( !fail.isEmpty() )
 							{
 								this.getCellInventory().injectItems( ais, Actionable.MODULATE, this.getActionSource() );
 							}
@@ -959,7 +959,7 @@ public abstract class AEBaseContainer extends Container
 					return;
 				}
 
-				if( player.inventory.getItemStack() == null )
+				if( player.inventory.getItemStack().isEmpty() )
 				{
 					if( slotItem != null )
 					{
@@ -972,7 +972,7 @@ public abstract class AEBaseContainer extends Container
 						}
 						else
 						{
-							player.inventory.setItemStack( null );
+							player.inventory.setItemStack( ItemStack.EMPTY );
 						}
 						this.updateHeld( player );
 					}
@@ -987,7 +987,7 @@ public abstract class AEBaseContainer extends Container
 					}
 					else
 					{
-						player.inventory.setItemStack( null );
+						player.inventory.setItemStack( ItemStack.EMPTY );
 					}
 					this.updateHeld( player );
 				}
@@ -999,7 +999,7 @@ public abstract class AEBaseContainer extends Container
 					return;
 				}
 
-				if( player.inventory.getItemStack() == null )
+				if( player.inventory.getItemStack().isEmpty() )
 				{
 					if( slotItem != null )
 					{
@@ -1021,7 +1021,7 @@ public abstract class AEBaseContainer extends Container
 						}
 						else
 						{
-							player.inventory.setItemStack( null );
+							player.inventory.setItemStack( ItemStack.EMPTY );
 						}
 						this.updateHeld( player );
 					}
@@ -1037,7 +1037,7 @@ public abstract class AEBaseContainer extends Container
 						is.setCount( is.getCount() - 1 );
 						if( is.getCount() <= 0 )
 						{
-							player.inventory.setItemStack( null );
+							player.inventory.setItemStack( ItemStack.EMPTY );
 						}
 						this.updateHeld( player );
 					}
@@ -1074,7 +1074,7 @@ public abstract class AEBaseContainer extends Container
 						myItem.setCount( (int) ais.getStackSize() );
 						myItem = adp.simulateAdd( myItem );
 
-						if( myItem != null )
+						if( !myItem.isEmpty() )
 						{
 							ais.setStackSize( ais.getStackSize() - myItem.getCount() );
 						}
@@ -1123,7 +1123,7 @@ public abstract class AEBaseContainer extends Container
 				this.getActionSource() );
 		if( ais == null )
 		{
-			return null;
+			return ItemStack.EMPTY;
 		}
 		return ais.getItemStack();
 	}
@@ -1202,42 +1202,42 @@ public abstract class AEBaseContainer extends Container
 		final ItemStack isB = b.getStack();
 
 		// something to do?
-		if( isA == null && isB == null )
+		if( isA.isEmpty() && isB.isEmpty() )
 		{
 			return;
 		}
 
 		// can take?
 
-		if( isA != null && !a.canTakeStack( this.getInventoryPlayer().player ) )
+		if( !isA.isEmpty() && !a.canTakeStack( this.getInventoryPlayer().player ) )
 		{
 			return;
 		}
 
-		if( isB != null && !b.canTakeStack( this.getInventoryPlayer().player ) )
+		if( !isB.isEmpty() && !b.canTakeStack( this.getInventoryPlayer().player ) )
 		{
 			return;
 		}
 
 		// swap valid?
 
-		if( isB != null && !a.isItemValid( isB ) )
+		if( !isB.isEmpty() && !a.isItemValid( isB ) )
 		{
 			return;
 		}
 
-		if( isA != null && !b.isItemValid( isA ) )
+		if( !isA.isEmpty() && !b.isItemValid( isA ) )
 		{
 			return;
 		}
 
-		ItemStack testA = isB == null ? null : isB.copy();
+		ItemStack testA = isB.isEmpty() ? ItemStack.EMPTY : isB.copy();
-		ItemStack testB = isA == null ? null : isA.copy();
+		ItemStack testB = isA.isEmpty() ? ItemStack.EMPTY : isA.copy();
 
 		// can put some back?
-		if( testA != null && testA.getCount() > a.getSlotStackLimit() )
+		if( !testA.isEmpty() && testA.getCount() > a.getSlotStackLimit() )
 		{
-			if( testB != null )
+			if( !testB.isEmpty() )
 			{
 				return;
 			}
@@ -1249,9 +1249,9 @@ public abstract class AEBaseContainer extends Container
 			testB.setCount( totalA - testA.getCount() );
 		}
 
-		if( testB != null && testB.getCount() > b.getSlotStackLimit() )
+		if( !testB.isEmpty() && testB.getCount() > b.getSlotStackLimit() )
 		{
-			if( testA != null )
+			if ( !testA.isEmpty() )
 			{
 				return;
 			}

src/main/java/appeng/container/implementations/ContainerCellWorkbench.java

@@ -210,7 +210,7 @@ public class ContainerCellWorkbench extends ContainerUpgradeable
 		final IInventory inv = this.getUpgradeable().getInventoryByName( "config" );
 		for( int x = 0; x < inv.getSizeInventory(); x++ )
 		{
-			inv.setInventorySlotContents( x, null );
+			inv.setInventorySlotContents( x, ItemStack.EMPTY );
 		}
 		this.detectAndSendChanges();
 	}
@@ -248,7 +248,7 @@ public class ContainerCellWorkbench extends ContainerUpgradeable
 			}
 			else
 			{
-				inv.setInventorySlotContents( x, null );
+				inv.setInventorySlotContents( x, ItemStack.EMPTY );
 			}
 		}
 

src/main/java/appeng/container/implementations/ContainerInscriber.java

@@ -126,11 +126,11 @@ public class ContainerInscriber extends ContainerUpgradeable implements IProgres
 
 			for( final IInscriberRecipe recipe : AEApi.instance().registries().inscriber().getRecipes() )
 			{
-				final boolean matchA = ( top == null && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( top, recipe.getTopOptional().orElse( null ) ) ) && // and...
+				final boolean matchA = ( top.isEmpty() && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( top, recipe.getTopOptional().orElse( ItemStack.EMPTY ) ) ) && // and...
-				( bot == null && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( bot, recipe.getBottomOptional().orElse( null ) ) );
+				( bot.isEmpty() && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( bot, recipe.getBottomOptional().orElse( ItemStack.EMPTY ) ) );
 
-				final boolean matchB = ( bot == null && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( bot, recipe.getTopOptional().orElse( null ) ) ) && // and...
+				final boolean matchB = ( bot.isEmpty() && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( bot, recipe.getTopOptional().orElse( ItemStack.EMPTY ) ) ) && // and...
-				( top == null && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( top, recipe.getBottomOptional().orElse( null ) ) );
+				( top.isEmpty() && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( top, recipe.getBottomOptional().orElse( ItemStack.EMPTY ) ) );
 
 				if( matchA || matchB )
 				{
@@ -151,9 +151,9 @@ public class ContainerInscriber extends ContainerUpgradeable implements IProgres
 			}
 		}
 
-		if( ( s == this.top && bot != null ) || ( s == this.bottom && top != null ) )
+		if( ( s == this.top && !bot.isEmpty() ) || ( s == this.bottom && !top.isEmpty() ) )
 		{
-			ItemStack otherSlot = null;
+			ItemStack otherSlot = ItemStack.EMPTY;
 			if( s == this.top )
 			{
 				otherSlot = this.bottom.getStack();
@@ -174,13 +174,13 @@ public class ContainerInscriber extends ContainerUpgradeable implements IProgres
 			boolean isValid = false;
 			for( final IInscriberRecipe recipe : AEApi.instance().registries().inscriber().getRecipes() )
 			{
-				if( Platform.itemComparisons().isSameItem( recipe.getTopOptional().orElse( null ), otherSlot ) )
+				if( Platform.itemComparisons().isSameItem( recipe.getTopOptional().orElse( ItemStack.EMPTY ), otherSlot ) )
 				{
-					isValid = Platform.itemComparisons().isSameItem( is, recipe.getBottomOptional().orElse( null ) );
+					isValid = Platform.itemComparisons().isSameItem( is, recipe.getBottomOptional().orElse( ItemStack.EMPTY ) );
 				}
-				else if( Platform.itemComparisons().isSameItem( recipe.getBottomOptional().orElse( null ), otherSlot ) )
+				else if( Platform.itemComparisons().isSameItem( recipe.getBottomOptional().orElse( ItemStack.EMPTY ), otherSlot ) )
 				{
-					isValid = Platform.itemComparisons().isSameItem( is, recipe.getTopOptional().orElse( null ) );
+					isValid = Platform.itemComparisons().isSameItem( is, recipe.getTopOptional().orElse( ItemStack.EMPTY ) );
 				}
 
 				if( isValid )

src/main/java/appeng/container/implementations/ContainerInterfaceTerminal.java

@@ -204,7 +204,7 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 		if( inv != null )
 		{
 			final ItemStack is = inv.server.getStackInSlot( slot );
-			final boolean hasItemInHand = player.inventory.getItemStack() != null;
+			final boolean hasItemInHand = !player.inventory.getItemStack().isEmpty();
 
 			final InventoryAdaptor playerHand = new AdaptorPlayerHand( player );
 
@@ -220,7 +220,7 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 					if( hasItemInHand )
 					{
 						ItemStack inSlot = theSlot.getStackInSlot( 0 );
-						if( inSlot == null )
+						if( inSlot.isEmpty() )
 						{
 							player.inventory.setItemStack( interfaceSlot.addItems( player.inventory.getItemStack() ) );
 						}
@@ -229,12 +229,12 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 							inSlot = inSlot.copy();
 							final ItemStack inHand = player.inventory.getItemStack().copy();
 
-							theSlot.setInventorySlotContents( 0, null );
+							theSlot.setInventorySlotContents( 0, ItemStack.EMPTY );
-							player.inventory.setItemStack( null );
+							player.inventory.setItemStack( ItemStack.EMPTY );
 
 							player.inventory.setItemStack( interfaceSlot.addItems( inHand.copy() ) );
 
-							if( player.inventory.getItemStack() == null )
+							if( player.inventory.getItemStack().isEmpty() )
 							{
 								player.inventory.setItemStack( inSlot );
 							}
@@ -256,24 +256,24 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 
 					if( hasItemInHand )
 					{
-						ItemStack extra = playerHand.removeItems( 1, null, null );
+						ItemStack extra = playerHand.removeItems( 1, ItemStack.EMPTY, null );
-						if( extra != null )
+						if( !extra.isEmpty() )
 						{
 							extra = interfaceSlot.addItems( extra );
 						}
-						if( extra != null )
+						if( !extra.isEmpty() )
 						{
 							playerHand.addItems( extra );
 						}
 					}
-					else if( is != null )
+					else if( !is.isEmpty() )
 					{
-						ItemStack extra = interfaceSlot.removeItems( ( is.getCount() + 1 ) / 2, null, null );
+						ItemStack extra = interfaceSlot.removeItems( ( is.getCount() + 1 ) / 2, ItemStack.EMPTY, null );
-						if( extra != null )
+						if( !extra.isEmpty() )
 						{
 							extra = playerHand.addItems( extra );
 						}
-						if( extra != null )
+						if( !extra.isEmpty() )
 						{
 							interfaceSlot.addItems( extra );
 						}
@@ -300,7 +300,7 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 
 					if( player.capabilities.isCreativeMode && !hasItemInHand )
 					{
-						player.inventory.setItemStack( is == null ? null : is.copy() );
+						player.inventory.setItemStack( is.isEmpty() ? ItemStack.EMPTY : is.copy() );
 					}
 
 					break;
@@ -357,12 +357,12 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 
 	private boolean isDifferent( final ItemStack a, final ItemStack b )
 	{
-		if( a == null && b == null )
+		if( a.isEmpty() && b.isEmpty() )
 		{
 			return false;
 		}
 
-		if( a == null || b == null )
+		if( a.isEmpty() || b.isEmpty() )
 		{
 			return true;
 		}
@@ -388,9 +388,9 @@ public final class ContainerInterfaceTerminal extends AEBaseContainer
 			final ItemStack is = inv.server.getStackInSlot( x + offset );
 
 			// "update" client side.
-			inv.client.setInventorySlotContents( x + offset, is == null ? null : is.copy() );
+			inv.client.setInventorySlotContents( x + offset, is.isEmpty() ? ItemStack.EMPTY : is.copy() );
 
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				is.writeToNBT( itemNBT );
 			}

src/main/java/appeng/container/implementations/ContainerMAC.java

@@ -57,7 +57,7 @@ public class ContainerMAC extends ContainerUpgradeable implements IProgressProvi
 		final IInventory mac = this.getUpgradeable().getInventoryByName( "mac" );
 
 		final ItemStack is = mac.getStackInSlot( 10 );
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return false;
 		}

src/main/java/appeng/container/implementations/ContainerMEPortableCell.java

@@ -65,7 +65,7 @@ public class ContainerMEPortableCell extends ContainerMEMonitorable
 		{
 			if( currentItem != this.civ.getItemStack() )
 			{
-				if( currentItem != null )
+				if( !currentItem.isEmpty() )
 				{
 					if( Platform.itemComparisons().isEqualItem( this.civ.getItemStack(), currentItem ) )
 					{

src/main/java/appeng/container/implementations/ContainerNetworkStatus.java

@@ -118,7 +118,7 @@ public class ContainerNetworkStatus extends AEBaseContainer
 					{
 						final IGridBlock blk = machine.getGridBlock();
 						final ItemStack is = blk.getMachineRepresentation();
-						if( is != null && is.getItem() != null )
+						if( !is.isEmpty() && is.getItem() != null )
 						{
 							final IAEItemStack ais = AEItemStack.create( is );
 							ais.setStackSize( 1 );

src/main/java/appeng/container/implementations/ContainerNetworkTool.java

@@ -70,7 +70,7 @@ public class ContainerNetworkTool extends AEBaseContainer
 
 		if( currentItem != this.toolInv.getItemStack() )
 		{
-			if( currentItem != null )
+			if( !currentItem.isEmpty() )
 			{
 				if( Platform.itemComparisons().isEqualItem( this.toolInv.getItemStack(), currentItem ) )
 				{

src/main/java/appeng/container/implementations/ContainerPatternTerm.java

@@ -190,14 +190,14 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 		}
 
 		// first check the output slots, should either be null, or a pattern
-		if( output != null && !this.isPattern( output ) )
+		if( !output.isEmpty() && !this.isPattern( output ) )
 		{
 			return;
 		} // if nothing is there we should snag a new pattern.
-		else if( output == null )
+		else if( output.isEmpty() )
 		{
 			output = this.patternSlotIN.getStack();
-			if( output == null || !this.isPattern( output ) )
+			if( output.isEmpty()  || !this.isPattern( output ) )
 			{
 				return; // no blanks.
 			}
@@ -206,7 +206,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 			output.setCount( output.getCount() );
 			if( output.getCount() == 0 )
 			{
-				this.patternSlotIN.putStack( null );
+				this.patternSlotIN.putStack( ItemStack.EMPTY );
 			}
 
 			// add a new encoded pattern.
@@ -250,7 +250,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 		for( int x = 0; x < this.craftingSlots.length; x++ )
 		{
 			input[x] = this.craftingSlots[x].getStack();
-			if( input[x] != null )
+			if( !input[x].isEmpty() )
 			{
 				hasValue = true;
 			}
@@ -270,7 +270,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 		{
 			final ItemStack out = this.getAndUpdateOutput();
 
-			if( out != null && out.getCount() > 0 )
+			if( !out.isEmpty() && out.getCount() > 0 )
 			{
 				return new ItemStack[] { out };
 			}
@@ -284,7 +284,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 			{
 				final ItemStack out = outputSlot.getStack();
 
-				if( out != null && out.getCount() > 0 )
+				if( !out.isEmpty() && out.getCount() > 0 )
 				{
 					list.add( out );
 					hasValue = true;
@@ -302,7 +302,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 
 	private boolean isPattern( final ItemStack output )
 	{
-		if( output == null )
+		if( output.isEmpty() )
 		{
 			return false;
 		}
@@ -357,7 +357,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 				inv = playerInv;
 			}
 
-			if( inv.simulateAdd( out.getItemStack() ) != null )
+			if( !inv.simulateAdd( out.getItemStack() ).isEmpty() )
 			{
 				return;
 			}
@@ -381,7 +381,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 
 			for( int x = 0; x < 9; x++ )
 			{
-				ic.setInventorySlotContents( x, packetPatternSlot.pattern[x] == null ? null : packetPatternSlot.pattern[x].getItemStack() );
+				ic.setInventorySlotContents( x, packetPatternSlot.pattern[x] == null ? ItemStack.EMPTY : packetPatternSlot.pattern[x].getItemStack() );
 			}
 
 			final IRecipe r = Platform.findMatchingRecipe( ic, p.world );
@@ -398,7 +398,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 
 			for( int x = 0; x < ic.getSizeInventory(); x++ )
 			{
-				if( ic.getStackInSlot( x ) != null )
+				if( !ic.getStackInSlot( x ).isEmpty() )
 				{
 					final ItemStack pulled = Platform.extractItemsByRecipe( this.getPowerSource(), this.getActionSource(), storage, p.world, r, is, ic, ic.getStackInSlot( x ), x, all, Actionable.MODULATE, ItemViewCell.createFilter( this.getViewCells() ) );
 					real.setInventorySlotContents( x, pulled );
@@ -416,7 +416,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 				{
 					final ItemStack failed = playerInv.addItems( real.getStackInSlot( x ) );
 
-					if( failed != null )
+					if( !failed.isEmpty() )
 					{
 						p.dropItem( failed, false );
 					}
@@ -434,7 +434,7 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 				for( int x = 0; x < real.getSizeInventory(); x++ )
 				{
 					final ItemStack failed = real.getStackInSlot( x );
-					if( failed != null )
+					if( !failed.isEmpty() )
 					{
 						this.getCellInventory().injectItems( AEItemStack.create( failed ), Actionable.MODULATE, new MachineSource( this.getPatternTerminal() ) );
 					}
@@ -498,12 +498,12 @@ public class ContainerPatternTerm extends ContainerMEMonitorable implements IAEA
 	{
 		for( final Slot s : this.craftingSlots )
 		{
-			s.putStack( null );
+			s.putStack( ItemStack.EMPTY );
 		}
 
 		for( final Slot s : this.outputSlots )
 		{
-			s.putStack( null );
+			s.putStack( ItemStack.EMPTY );
 		}
 
 		this.detectAndSendChanges();

src/main/java/appeng/container/implementations/ContainerQuartzKnife.java

@@ -143,7 +143,7 @@ public class ContainerQuartzKnife extends AEBaseContainer implements IAEAppEngIn
 					compound.setString( "InscribeName", this.myName );
 
 					return namePressStack;
-				} ).orElse( null );
+				} ).orElse( ItemStack.EMPTY );
 			}
 		}
 
@@ -154,7 +154,7 @@ public class ContainerQuartzKnife extends AEBaseContainer implements IAEAppEngIn
 	public ItemStack decrStackSize( final int var1, final int var2 )
 	{
 		final ItemStack is = this.getStackInSlot( 0 );
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			if( this.makePlate() )
 			{
@@ -272,7 +272,7 @@ public class ContainerQuartzKnife extends AEBaseContainer implements IAEAppEngIn
 	@Override
 	public void clear()
 	{
-		this.inSlot.setInventorySlotContents( 0, null );
+		this.inSlot.setInventorySlotContents( 0, ItemStack.EMPTY );
 	}
 
 	@Override

src/main/java/appeng/container/implementations/ContainerSecurityStation.java

@@ -75,7 +75,7 @@ public class ContainerSecurityStation extends ContainerMEMonitorable implements
 			final SecurityPermissions permission = SecurityPermissions.valueOf( value );
 
 			final ItemStack a = this.configSlot.getStack();
-			if( a != null && a.getItem() instanceof IBiometricCard )
+			if( !a.isEmpty() && a.getItem() instanceof IBiometricCard )
 			{
 				final IBiometricCard bc = (IBiometricCard) a.getItem();
 				if( bc.hasPermission( a, permission ) )
@@ -102,7 +102,7 @@ public class ContainerSecurityStation extends ContainerMEMonitorable implements
 		this.setPermissionMode( 0 );
 
 		final ItemStack a = this.configSlot.getStack();
-		if( a != null && a.getItem() instanceof IBiometricCard )
+		if( !a.isEmpty() && a.getItem() instanceof IBiometricCard )
 		{
 			final IBiometricCard bc = (IBiometricCard) a.getItem();
 
@@ -164,7 +164,7 @@ public class ContainerSecurityStation extends ContainerMEMonitorable implements
 				{
 					networkEncodable.setEncryptionKey( term, String.valueOf( this.securityBox.getSecurityKey() ), "" );
 
-					this.wirelessIn.putStack( null );
+					this.wirelessIn.putStack( ItemStack.EMPTY );
 					this.wirelessOut.putStack( term );
 
 					// update the two slots in question...

src/main/java/appeng/container/implementations/ContainerStorageBus.java

@@ -137,7 +137,7 @@ public class ContainerStorageBus extends ContainerUpgradeable
 		final IInventory inv = this.getUpgradeable().getInventoryByName( "config" );
 		for( int x = 0; x < inv.getSizeInventory(); x++ )
 		{
-			inv.setInventorySlotContents( x, null );
+			inv.setInventorySlotContents( x, ItemStack.EMPTY );
 		}
 		this.detectAndSendChanges();
 	}
@@ -165,7 +165,7 @@ public class ContainerStorageBus extends ContainerUpgradeable
 			}
 			else
 			{
-				inv.setInventorySlotContents( x, null );
+				inv.setInventorySlotContents( x, ItemStack.EMPTY );
 			}
 		}
 

src/main/java/appeng/container/implementations/ContainerUpgradeable.java

@@ -97,7 +97,7 @@ public class ContainerUpgradeable extends AEBaseContainer implements IOptionalSl
 		for( int x = 0; x < pi.getSizeInventory(); x++ )
 		{
 			final ItemStack pii = pi.getStackInSlot( x );
-			if( pii != null && pii.getItem() instanceof ToolNetworkTool )
+			if( !pii.isEmpty() && pii.getItem() instanceof ToolNetworkTool )
 			{
 				this.lockPlayerInventorySlot( x );
 				this.tbSlot = x;
@@ -204,7 +204,7 @@ public class ContainerUpgradeable extends AEBaseContainer implements IOptionalSl
 			if( o instanceof OptionalSlotFake )
 			{
 				final OptionalSlotFake fs = (OptionalSlotFake) o;
-				if( !fs.isEnabled() && fs.getDisplayStack() != null )
+				if( !fs.isEnabled() && !fs.getDisplayStack().isEmpty() )
 				{
 					fs.clearStack();
 				}
@@ -233,7 +233,7 @@ public class ContainerUpgradeable extends AEBaseContainer implements IOptionalSl
 
 			if( currentItem != this.tbInventory.getItemStack() )
 			{
-				if( currentItem != null )
+				if( !currentItem.isEmpty() )
 				{
 					if( Platform.itemComparisons().isEqualItem( this.tbInventory.getItemStack(), currentItem ) )
 					{

src/main/java/appeng/container/implementations/ContainerWireless.java

@@ -51,7 +51,7 @@ public class ContainerWireless extends AEBaseContainer
 	@Override
 	public void detectAndSendChanges()
 	{
-		final int boosters = this.boosterSlot.getStack() == null ? 0 : this.boosterSlot.getStack().getCount();
+		final int boosters = this.boosterSlot.getStack().isEmpty() ? 0 : this.boosterSlot.getStack().getCount();
 
 		this.setRange( (long) ( 10 * AEConfig.instance().wireless_getMaxRange( boosters ) ) );
 		this.setDrain( (long) ( 100 * AEConfig.instance().wireless_getPowerDrain( boosters ) ) );

src/main/java/appeng/container/slot/AppEngCraftingSlot.java

@@ -167,14 +167,14 @@ public class AppEngCraftingSlot extends AppEngSlot
 			final ItemStack itemstack1 = this.craftMatrix.getStackInSlot( i );
 			final ItemStack itemstack2 = aitemstack.get( i );
 
-			if( itemstack1 != null )
+			if( !itemstack1.isEmpty() )
 			{
 				this.craftMatrix.decrStackSize( i, 1 );
 			}
 
-			if( itemstack2 != null )
+			if( !itemstack2.isEmpty() )
 			{
-				if( this.craftMatrix.getStackInSlot( i ) == null )
+				if( this.craftMatrix.getStackInSlot( i ).isEmpty() )
 				{
 					this.craftMatrix.setInventorySlotContents( i, itemstack2 );
 				}

src/main/java/appeng/container/slot/AppEngSlot.java

@@ -67,7 +67,7 @@ public class AppEngSlot extends Slot
 
 	public void clearStack()
 	{
-		super.putStack( null );
+		super.putStack( ItemStack.EMPTY );
 	}
 
 	@Override

src/main/java/appeng/container/slot/OptionalSlotFake.java

@@ -46,7 +46,7 @@ public class OptionalSlotFake extends SlotFake
 	{
 		if( !this.isEnabled() )
 		{
-			if( this.getDisplayStack() != null )
+			if( !this.getDisplayStack().isEmpty() )
 			{
 				this.clearStack();
 			}

src/main/java/appeng/container/slot/OptionalSlotFakeTypeOnly.java

@@ -34,7 +34,7 @@ public class OptionalSlotFakeTypeOnly extends OptionalSlotFake
 	@Override
 	public void putStack( ItemStack is )
 	{
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			is = is.copy();
 			if( is.getCount() > 1 )

src/main/java/appeng/container/slot/SlotCraftingTerm.java

@@ -89,7 +89,7 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 
 	public void doClick( final InventoryAction action, final EntityPlayer who )
 	{
-		if( this.getStack() == null )
+		if( this.getStack().isEmpty() )
 		{
 			return;
 		}
@@ -128,18 +128,18 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 		}
 
 		final ItemStack rs = Platform.cloneItemStack( this.getStack() );
-		if( rs == null )
+		if( rs.isEmpty() )
 		{
 			return;
 		}
 
 		for( int x = 0; x < maxTimesToCraft; x++ )
 		{
-			if( ia.simulateAdd( rs ) == null )
+			if( ia.simulateAdd( rs ).isEmpty() )
 			{
 				final IItemList<IAEItemStack> all = inv.getStorageList();
 				final ItemStack extra = ia.addItems( this.craftItem( who, rs, inv, all ) );
-				if( extra != null )
+				if( !extra.isEmpty() )
 				{
 					final List<ItemStack> drops = new ArrayList<ItemStack>();
 					drops.add( extra );
@@ -160,7 +160,7 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 		// update crafting matrix...
 		ItemStack is = this.getStack();
 
-		if( is != null && Platform.itemComparisons().isEqualItem( request, is ) )
+		if( !is.isEmpty() && Platform.itemComparisons().isEqualItem( request, is ) )
 		{
 			final ItemStack[] set = new ItemStack[this.getPattern().getSizeInventory()];
 			// Safeguard for empty slots in the inventory for now
@@ -186,7 +186,7 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 						for( int x = 0; x < ic.getSizeInventory(); x++ )
 						{
 							final ItemStack pis = ic.getStackInSlot( x );
-							if( pis == null )
+							if( pis.isEmpty() )
 							{
 								continue;
 							}
@@ -212,7 +212,7 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 				{
 					for( int x = 0; x < this.getPattern().getSizeInventory(); x++ )
 					{
-						if( this.getPattern().getStackInSlot( x ) != null )
+						if( !this.getPattern().getStackInSlot( x ).isEmpty() )
 						{
 							set[x] = Platform.extractItemsByRecipe( this.energySrc, this.mySrc, inv, p.world, r, is, ic, this.getPattern().getStackInSlot( x ), x, all, Actionable.MODULATE, ItemViewCell.createFilter( this.container.getViewCells() ) );
 							ic.setInventorySlotContents( x, set[x] );
@@ -257,11 +257,11 @@ public class SlotCraftingTerm extends AppEngCraftingSlot
 			// set new items onto the crafting table...
 			for( int x = 0; x < this.craftInv.getSizeInventory(); x++ )
 			{
-				if( this.craftInv.getStackInSlot( x ) == null )
+				if( this.craftInv.getStackInSlot( x ).isEmpty() )
 				{
 					this.craftInv.setInventorySlotContents( x, set[x] );
 				}
-				else if( set[x] != null )
+				else if( !set[x].isEmpty() )
 				{
 					// eek! put it back!
 					final IAEItemStack fail = inv.injectItems( AEItemStack.create( set[x] ), Actionable.MODULATE, this.mySrc );

src/main/java/appeng/container/slot/SlotFake.java

@@ -53,7 +53,7 @@ public class SlotFake extends AppEngSlot
 	@Override
 	public void putStack( ItemStack is )
 	{
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			is = is.copy();
 		}

src/main/java/appeng/container/slot/SlotFakeTypeOnly.java

@@ -34,7 +34,7 @@ public class SlotFakeTypeOnly extends SlotFake
 	@Override
 	public void putStack( ItemStack is )
 	{
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			is = is.copy();
 			if( is.getCount() > 1 )

src/main/java/appeng/container/slot/SlotInaccessible.java

@@ -27,7 +27,7 @@ import net.minecraft.item.ItemStack;
 public class SlotInaccessible extends AppEngSlot
 {
 
-	private ItemStack dspStack = null;
+	private ItemStack dspStack = ItemStack.EMPTY;
 
 	public SlotInaccessible( final IInventory i, final int slotIdx, final int x, final int y )
 	{
@@ -44,7 +44,7 @@ public class SlotInaccessible extends AppEngSlot
 	public void onSlotChanged()
 	{
 		super.onSlotChanged();
-		this.dspStack = null;
+		this.dspStack = ItemStack.EMPTY;
 	}
 
 	@Override
@@ -56,10 +56,10 @@ public class SlotInaccessible extends AppEngSlot
 	@Override
 	public ItemStack getDisplayStack()
 	{
-		if( this.dspStack == null )
+		if( this.dspStack.isEmpty() )
 		{
 			final ItemStack dsp = super.getDisplayStack();
-			if( dsp != null )
+			if( !dsp.isEmpty() )
 			{
 				this.dspStack = dsp.copy();
 			}

src/main/java/appeng/container/slot/SlotRestrictedInput.java

@@ -101,7 +101,7 @@ public class SlotRestrictedInput extends AppEngSlot
 			return false;
 		}
 
-		if( i == null )
+		if( i.isEmpty() )
 		{
 			return false;
 		}
@@ -243,11 +243,11 @@ public class SlotRestrictedInput extends AppEngSlot
 		if( Platform.isClient() && ( this.which == PlacableItemType.ENCODED_PATTERN ) )
 		{
 			final ItemStack is = super.getStack();
-			if( is != null && is.getItem() instanceof ItemEncodedPattern )
+			if( !is.isEmpty() && is.getItem() instanceof ItemEncodedPattern )
 			{
 				final ItemEncodedPattern iep = (ItemEncodedPattern) is.getItem();
 				final ItemStack out = iep.getOutput( is );
-				if( out != null )
+				if( !out.isEmpty() )
 				{
 					return out;
 				}

src/main/java/appeng/core/api/imc/IMCBlackListSpatial.java

@@ -36,7 +36,7 @@ public class IMCBlackListSpatial implements IIMCProcessor
 	{
 
 		final ItemStack is = m.getItemStackValue();
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			final Block blk = Block.getBlockFromItem( is.getItem() );
 			if( blk != null )

src/main/java/appeng/core/api/imc/IMCP2PAttunement.java

@@ -54,7 +54,7 @@ public class IMCP2PAttunement implements IIMCProcessor
 		if( type != null )
 		{
 			final ItemStack is = m.getItemStackValue();
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				AEApi.instance().registries().p2pTunnel().addNewAttunement( is, type );
 			}

src/main/java/appeng/core/features/ColoredItemDefinition.java

@@ -92,7 +92,7 @@ public final class ColoredItemDefinition implements AEColoredItemDefinition
 	{
 		final ItemStackSrc is = this.colors[color.ordinal()];
 
-		if( comparableItem == null || is == null )
+		if( comparableItem.isEmpty() || is == null )
 		{
 			return false;
 		}

src/main/java/appeng/core/features/registries/cell/CellRegistry.java

@@ -53,7 +53,7 @@ public class CellRegistry implements ICellRegistry
 	@Override
 	public boolean isCellHandled( final ItemStack is )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return false;
 		}
@@ -70,7 +70,7 @@ public class CellRegistry implements ICellRegistry
 	@Override
 	public ICellHandler getHandler( final ItemStack is )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return null;
 		}
@@ -87,7 +87,7 @@ public class CellRegistry implements ICellRegistry
 	@Override
 	public IMEInventoryHandler getCellInventory( final ItemStack is, final ISaveProvider container, final StorageChannel chan )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return null;
 		}

src/main/java/appeng/core/features/registries/cell/CreativeCellHandler.java

@@ -42,13 +42,13 @@ public class CreativeCellHandler implements ICellHandler
 	@Override
 	public boolean isCell( final ItemStack is )
 	{
-		return is != null && is.getItem() instanceof ItemCreativeStorageCell;
+		return !is.isEmpty() && is.getItem() instanceof ItemCreativeStorageCell;
 	}
 
 	@Override
 	public IMEInventoryHandler getCellInventory( final ItemStack is, final ISaveProvider container, final StorageChannel channel )
 	{
-		if( channel == StorageChannel.ITEMS && is != null && is.getItem() instanceof ItemCreativeStorageCell )
+		if( channel == StorageChannel.ITEMS && !is.isEmpty() && is.getItem() instanceof ItemCreativeStorageCell )
 		{
 			return CreativeCellInventory.getCell( is );
 		}

src/main/java/appeng/core/features/registries/grinder/GrinderRecipeManager.java

@@ -229,7 +229,7 @@ public final class GrinderRecipeManager implements IGrinderRegistry, IOreListene
 
 	private ItemStack copy( final ItemStack is )
 	{
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			return is.copy();
 		}

src/main/java/appeng/core/features/registries/inscriber/InscriberRegistry.java

@@ -182,11 +182,11 @@ public final class InscriberRegistry implements IInscriberRegistry
 			{
 				throw new IllegalStateException( "Input must have a size." );
 			}
-			if( this.output == null )
+			if( this.output.isEmpty() )
 			{
 				throw new IllegalStateException( "Output must be defined." );
 			}
-			if( this.topOptional == null && this.bottomOptional == null )
+			if( this.topOptional.isEmpty() && this.bottomOptional.isEmpty() )
 			{
 				throw new IllegalStateException( "One optional must be defined." );
 			}

src/main/java/appeng/core/stats/Achievements.java

@@ -124,7 +124,7 @@ public enum Achievements
 
 	Achievements( final int x, final int y, final IItemDefinition which, final AchievementType type )
 	{
-		this.stack = which.maybeStack( 1 ).orElse( null );
+		this.stack = which.maybeStack( 1 ).orElse( ItemStack.EMPTY );
 		this.type = type;
 		this.x = x;
 		this.y = y;

src/main/java/appeng/core/sync/GuiBridge.java

@@ -255,7 +255,7 @@ public enum GuiBridge implements IGuiHandler
 		final boolean stem = ( ( ordinal >> 3 ) & 1 ) == 1;
 		if( ID.type.isItem() )
 		{
-			ItemStack it = null;
+			ItemStack it = ItemStack.EMPTY;
 			if( stem )
 			{
 				it = player.inventory.getCurrentItem();
@@ -295,7 +295,7 @@ public enum GuiBridge implements IGuiHandler
 
 	private Object getGuiObject( final ItemStack it, final EntityPlayer player, final World w, final int x, final int y, final int z )
 	{
-		if( it != null )
+		if( !it.isEmpty() )
 		{
 			if( it.getItem() instanceof IGuiItem )
 			{
@@ -437,7 +437,7 @@ public enum GuiBridge implements IGuiHandler
 		final boolean stem = ( ( ordinal >> 3 ) & 1 ) == 1;
 		if( ID.type.isItem() )
 		{
-			ItemStack it = null;
+			ItemStack it = ItemStack.EMPTY;
 			if( stem )
 			{
 				it = player.inventory.getCurrentItem();
@@ -510,7 +510,7 @@ public enum GuiBridge implements IGuiHandler
 			if( this.type.isItem() )
 			{
 				final ItemStack it = player.inventory.getCurrentItem();
-				if( it != null && it.getItem() instanceof IGuiItem )
+				if( !it.isEmpty() && it.getItem() instanceof IGuiItem )
 				{
 					final Object myItem = ( (IGuiItem) it.getItem() ).getGuiObject( it, w, pos );
 					if( this.CorrectTileOrPart( myItem ) )

src/main/java/appeng/core/sync/packets/PacketClick.java

@@ -106,7 +106,7 @@ public class PacketClick extends AppEngPacket
 		final IComparableDefinition maybeMemoryCard = items.memoryCard();
 		final IComparableDefinition maybeColorApplicator = items.colorApplicator();
 
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			if( is.getItem() instanceof ToolNetworkTool )
 			{

src/main/java/appeng/core/sync/packets/PacketInventoryAction.java

@@ -167,7 +167,7 @@ public class PacketInventoryAction extends AppEngPacket
 		{
 			if( this.slotItem == null )
 			{
-				AppEng.proxy.getPlayers().get( 0 ).inventory.setItemStack( null );
+				AppEng.proxy.getPlayers().get( 0 ).inventory.setItemStack( ItemStack.EMPTY );
 			}
 			else
 			{

src/main/java/appeng/core/sync/packets/PacketJEIRecipe.java

@@ -150,7 +150,7 @@ public class PacketJEIRecipe extends AppEngPacket
 					{
 						final ItemStack is = r.getCraftingResult( testInv );
 
-						if( is != null )
+						if( !is.isEmpty() )
 						{
 							final IMEMonitor<IAEItemStack> storage = inv.getItemInventory();
 							final IItemList all = storage.getStorageList();
@@ -161,13 +161,13 @@ public class PacketJEIRecipe extends AppEngPacket
 								final ItemStack patternItem = testInv.getStackInSlot( x );
 
 								ItemStack currentItem = craftMatrix.getStackInSlot( x );
-								if( currentItem != null )
+								if( !currentItem.isEmpty() )
 								{
 									testInv.setInventorySlotContents( x, currentItem );
-									final ItemStack newItemStack = r.matches( testInv, pmp.world ) ? r.getCraftingResult( testInv ) : null;
+									final ItemStack newItemStack = r.matches( testInv, pmp.world ) ? r.getCraftingResult( testInv ) : ItemStack.EMPTY;
 									testInv.setInventorySlotContents( x, patternItem );
 
-									if( newItemStack == null || !Platform.itemComparisons().isSameItem( newItemStack, is ) )
+									if( newItemStack.isEmpty() || !Platform.itemComparisons().isSameItem( newItemStack, is ) )
 									{
 										final IAEItemStack in = AEItemStack.create( currentItem );
 										if( in != null )
@@ -179,7 +179,7 @@ public class PacketJEIRecipe extends AppEngPacket
 											}
 											else
 											{
-												craftMatrix.setInventorySlotContents( x, null );
+												craftMatrix.setInventorySlotContents( x, ItemStack.EMPTY );
 											}
 
 											currentItem = craftMatrix.getStackInSlot( x );
@@ -188,14 +188,14 @@ public class PacketJEIRecipe extends AppEngPacket
 								}
 
 								// True if we need to fetch an item for the recipe
-								if( patternItem != null && currentItem == null )
+								if( !patternItem.isEmpty() && currentItem.isEmpty() )
 								{
 									// Grab from network by recipe
 									ItemStack whichItem = Platform.extractItemsByRecipe( energy, cct.getActionSource(), storage, player.world, r, is, testInv, patternItem, x, all, realForFake, filter );
 
 									// If that doesn't get it, grab exact items from network (?)
 									// TODO see if this code is necessary
-									if( whichItem == null )
+									if( whichItem.isEmpty() )
 									{
 										for( int y = 0; y < this.recipe[x].length; y++ )
 										{
@@ -217,7 +217,7 @@ public class PacketJEIRecipe extends AppEngPacket
 									}
 
 									// If that doesn't work, grab from the player's inventory
-									if( whichItem == null && playerInventory != null )
+									if( whichItem.isEmpty() && playerInventory != null )
 									{
 										whichItem = this.extractItemFromPlayerInventory( player, realForFake, patternItem );
 									}

src/main/java/appeng/crafting/CraftingTreeProcess.java

@@ -73,7 +73,7 @@ public class CraftingTreeProcess
 			final IAEItemStack[] is = details.getInputs();
 			for( int x = 0; x < ic.getSizeInventory(); x++ )
 			{
-				ic.setInventorySlotContents( x, is[x] == null ? null : is[x].getItemStack() );
+				ic.setInventorySlotContents( x, is[x] == null ? ItemStack.EMPTY : is[x].getItemStack() );
 			}
 
 			FMLCommonHandler.instance().firePlayerCraftingEvent( Platform.getPlayer( (WorldServer) world ), details.getOutput( ic, world ), ic );
@@ -81,7 +81,7 @@ public class CraftingTreeProcess
 			for( int x = 0; x < ic.getSizeInventory(); x++ )
 			{
 				final ItemStack g = ic.getStackInSlot( x );
-				if( g != null && g.getCount() > 1 )
+				if( !g.isEmpty() && g.getCount() > 1 )
 				{
 					this.fullSimulation = true;
 				}
@@ -94,7 +94,7 @@ public class CraftingTreeProcess
 				boolean isAnInput = false;
 				for( final IAEItemStack a : details.getCondensedOutputs() )
 				{
-					if( g != null && a != null && a.equals( g ) )
+					if( !g.isEmpty() && a != null && a.equals( g ) )
 					{
 						isAnInput = true;
 					}
@@ -151,7 +151,7 @@ public class CraftingTreeProcess
 				boolean isAnInput = false;
 				for( final IAEItemStack a : details.getCondensedOutputs() )
 				{
-					if( g != null && a != null && a.equals( g ) )
+					if( !g.isEmpty() && a != null && a.equals( g ) )
 					{
 						isAnInput = true;
 					}

src/main/java/appeng/debug/TileCubeGenerator.java

@@ -37,14 +37,14 @@ public class TileCubeGenerator extends AEBaseTile implements ITickable
 {
 
 	private int size = 3;
-	private ItemStack is = null;
+	private ItemStack is = ItemStack.EMPTY;
 	private int countdown = 20 * 10;
 	private EntityPlayer who = null;
 
 	@Override
 	public void update()
 	{
-		if( this.is != null && Platform.isServer() )
+		if( !this.is.isEmpty() && Platform.isServer() )
 		{
 			this.countdown--;
 
@@ -92,9 +92,9 @@ public class TileCubeGenerator extends AEBaseTile implements ITickable
 			final ItemStack hand = player.inventory.getCurrentItem();
 			this.who = player;
 
-			if( hand == null )
+			if( hand.isEmpty() )
 			{
-				this.is = null;
+				this.is = ItemStack.EMPTY;
 
 				if( player.isSneaking() )
 				{

src/main/java/appeng/debug/TileItemGen.java

@@ -23,6 +23,7 @@ import java.util.LinkedList;
 import java.util.Queue;
 
 import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.init.Blocks;
 import net.minecraft.inventory.IInventory;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
@@ -78,7 +79,10 @@ public class TileItemGen extends AEBaseTile implements IInventory
 
 	private ItemStack getRandomItem()
 	{
-		return POSSIBLE_ITEMS.peek();
+		// Safeguard for crash
+		ItemStack testStack = POSSIBLE_ITEMS.peek();
+		if( testStack.isEmpty() ) testStack = new ItemStack(Blocks.COBBLESTONE, 1);
+		return testStack;
 	}
 
 	@Override

src/main/java/appeng/decorative/solid/BlockSkyStone.java

@@ -64,7 +64,7 @@ public class BlockSkyStone extends AEBaseBlock
 			final ItemStack is = event.getEntityPlayer().getItemStackFromSlot( EntityEquipmentSlot.MAINHAND );
 			int level = -1;
 
-			if( is != null && is.getItem() != null )
+			if( !is.isEmpty() && is.getItem() != null )
 			{
 				level = is.getItem().getHarvestLevel( is, "pickaxe", event.getEntityPlayer(), event.getState() );
 			}

src/main/java/appeng/facade/FacadeContainer.java

@@ -165,7 +165,7 @@ public class FacadeContainer implements IFacadeContainer
 			if( t != null )
 			{
 				final ItemStack is = new ItemStack( t );
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					final Item i = is.getItem();
 					if( i instanceof IFacadeItem )

src/main/java/appeng/facade/FacadePart.java

@@ -88,7 +88,7 @@ public class FacadePart implements IFacadePart, IBoxProvider
 	public Item getItem()
 	{
 		final ItemStack is = this.getTextureItem();
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return null;
 		}
@@ -99,7 +99,7 @@ public class FacadePart implements IFacadePart, IBoxProvider
 	public int getItemDamage()
 	{
 		final ItemStack is = this.getTextureItem();
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return 0;
 		}

src/main/java/appeng/helpers/DualityInterface.java

@@ -178,7 +178,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 		{
 			this.readConfig();
 		}
-		else if( inv == this.patterns && ( removed != null || added != null ) )
+		else if( inv == this.patterns && ( !removed.isEmpty() || !added.isEmpty() ) )
 		{
 			this.updateCraftingList();
 		}
@@ -264,7 +264,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 	private void addToSendList( final ItemStack is )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return;
 		}
@@ -292,7 +292,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 		for( final ItemStack p : this.config )
 		{
-			if( p != null )
+			if( !p.isEmpty() )
 			{
 				this.hasConfig = true;
 				break;
@@ -408,13 +408,13 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 		IAEItemStack req = this.config.getAEStackInSlot( slot );
 		if( req != null && req.getStackSize() <= 0 )
 		{
-			this.config.setInventorySlotContents( slot, null );
+			this.config.setInventorySlotContents( slot, ItemStack.EMPTY );
 			req = null;
 		}
 
 		final ItemStack Stored = this.storage.getStackInSlot( slot );
 
-		if( req == null && Stored != null )
+		if( req == null && !Stored.isEmpty() )
 		{
 			final IAEItemStack work = AEApi.instance().storage().createItemStack( Stored );
 			this.requireWork[slot] = work.setStackSize( -work.getStackSize() );
@@ -422,7 +422,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 		}
 		else if( req != null )
 		{
-			if( Stored == null ) // need to add stuff!
+			if( Stored.isEmpty() ) // need to add stuff!
 			{
 				this.requireWork[slot] = req.copy();
 				return;
@@ -474,7 +474,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 	private void addToCraftingList( final ItemStack is )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return;
 		}
@@ -561,7 +561,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 	{
 		for( int slot = 0; slot < this.storage.getSizeInventory(); slot++ )
 		{
-			this.onChangeInventory( this.storage, slot, InvOperation.markDirty, null, null );
+			this.onChangeInventory( this.storage, slot, InvOperation.markDirty, ItemStack.EMPTY, ItemStack.EMPTY );
 		}
 	}
 
@@ -621,23 +621,23 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 				{
 					final ItemStack result = ad.addItems( whatToSend );
 
-					if( result == null )
+					if( result.isEmpty() )
 					{
-						whatToSend = null;
+						whatToSend = ItemStack.EMPTY;
 					}
 					else
 					{
 						whatToSend.setCount( whatToSend.getCount() - (whatToSend.getCount() - result.getCount()) );
 					}
 
-					if( whatToSend == null )
+					if( whatToSend.isEmpty() )
 					{
 						break;
 					}
 				}
 			}
 
-			if( whatToSend == null )
+			if( whatToSend.isEmpty() )
 			{
 				i.remove();
 			}
@@ -682,7 +682,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 			else if( itemStack.getStackSize() > 0 )
 			{
 				// make sure strange things didn't happen...
-				if( adaptor.simulateAdd( itemStack.getItemStack() ) != null )
+				if( !adaptor.simulateAdd( itemStack.getItemStack() ).isEmpty() )
 				{
 					changed = true;
 					throw new GridAccessException();
@@ -693,7 +693,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 				{
 					changed = true;
 					final ItemStack issue = adaptor.addItems( acquired.getItemStack() );
-					if( issue != null )
+					if( !issue.isEmpty() )
 					{
 						throw new IllegalStateException( "bad attempt at managing inventory. ( addItems )" );
 					}
@@ -712,7 +712,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 				// make sure strange things didn't happen...
 				final ItemStack canExtract = adaptor.simulateRemove( (int) diff, toStore.getItemStack(), null );
-				if( canExtract == null || canExtract.getCount() != diff )
+				if( canExtract.isEmpty() || canExtract.getCount() != diff )
 				{
 					changed = true;
 					throw new GridAccessException();
@@ -729,8 +729,8 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 				{
 					// extract items!
 					changed = true;
-					final ItemStack removed = adaptor.removeItems( (int) diff, null, null );
+					final ItemStack removed = adaptor.removeItems( (int) diff, ItemStack.EMPTY, null );
-					if( removed == null )
+					if( removed.isEmpty() )
 					{
 						throw new IllegalStateException( "bad attempt at managing inventory. ( removeItems )" );
 					}
@@ -949,7 +949,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 			{
 				if( this.isBlocking() )
 				{
-					if( ad.simulateRemove( 1, null, null ) != null )
+					if( !ad.simulateRemove( 1, ItemStack.EMPTY, null ).isEmpty() )
 					{
 						continue;
 					}
@@ -960,7 +960,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 					for( int x = 0; x < table.getSizeInventory(); x++ )
 					{
 						final ItemStack is = table.getStackInSlot( x );
-						if( is != null )
+						if( !is.isEmpty() )
 						{
 							final ItemStack added = ad.addItems( is );
 							this.addToSendList( added );
@@ -1000,7 +1000,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 				final InventoryAdaptor ad = InventoryAdaptor.getAdaptor( te, s.getOpposite() );
 				if( ad != null )
 				{
-					if( ad.simulateRemove( 1, null, null ) == null )
+					if( !ad.simulateRemove( 1, ItemStack.EMPTY, null ).isEmpty() )
 					{
 						allAreBusy = false;
 						break;
@@ -1029,12 +1029,12 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 		for( int x = 0; x < table.getSizeInventory(); x++ )
 		{
 			final ItemStack is = table.getStackInSlot( x );
-			if( is == null )
+			if( is.isEmpty() )
 			{
 				continue;
 			}
 
-			if( ad.simulateAdd( is.copy() ) != null )
+			if( !ad.simulateAdd( is.copy() ).isEmpty() )
 			{
 				return false;
 			}
@@ -1062,7 +1062,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 		{
 			for( final ItemStack is : this.waitingToSend )
 			{
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					drops.add( is );
 				}
@@ -1071,7 +1071,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 		for( final ItemStack is : this.upgrades )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -1079,7 +1079,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 		for( final ItemStack is : this.storage )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -1087,7 +1087,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 
 		for( final ItemStack is : this.patterns )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -1213,7 +1213,7 @@ public class DualityInterface implements IGridTickable, IStorageMonitorable, IIn
 						if( mop.getBlockPos().equals( directedTile.getPos() ) )
 						{
 							final ItemStack g = directedBlock.getPickBlock( directedBlockState, mop, hostWorld, directedTile.getPos(), null );
-							if( g != null )
+							if( !g.isEmpty() )
 							{
 								what = g;
 							}

src/main/java/appeng/helpers/MultiCraftingTracker.java

@@ -83,7 +83,7 @@ public class MultiCraftingTracker
 
 	public boolean handleCrafting( final int x, final long itemToCraft, final IAEItemStack ais, final InventoryAdaptor d, final World w, final IGrid g, final ICraftingGrid cg, final BaseActionSource mySrc )
 	{
-		if( ais != null && d.simulateAdd( ais.getItemStack() ) == null )
+		if( ais != null && d.simulateAdd( ais.getItemStack() ).isEmpty() )
 		{
 			final Future<ICraftingJob> craftingJob = this.getJob( x );
 

src/main/java/appeng/integration/modules/jei/FacadeRecipeWrapper.java

@@ -65,17 +65,17 @@ class FacadeRecipeWrapper extends BlankRecipeWrapper implements IShapedCraftingR
 	{
 		List<ItemStack> input = new ArrayList<>( 9 );
 
-		input.add( null );
+		input.add( ItemStack.EMPTY );
 		input.add( cableAnchor );
-		input.add( null );
+		input.add( ItemStack.EMPTY );
 
 		input.add( cableAnchor );
 		input.add( textureItem );
 		input.add( cableAnchor );
 
-		input.add( null );
+		input.add( ItemStack.EMPTY );
 		input.add( cableAnchor );
-		input.add( null );
+		input.add( ItemStack.EMPTY );
 
 		ingredients.setInputs( ItemStack.class, input );
 		ingredients.setOutput( ItemStack.class, facade );

src/main/java/appeng/integration/modules/jei/InscriberRecipeWrapper.java

@@ -45,9 +45,9 @@ class InscriberRecipeWrapper extends BlankRecipeWrapper
 	public void getIngredients( IIngredients ingredients )
 	{
 		List<List<ItemStack>> inputSlots = new ArrayList<>( 3 );
-		inputSlots.add( Collections.singletonList( recipe.getTopOptional().orElse( null ) ) );
+		inputSlots.add( Collections.singletonList( recipe.getTopOptional().orElse( ItemStack.EMPTY ) ) );
 		inputSlots.add( recipe.getInputs() );
-		inputSlots.add( Collections.singletonList( recipe.getBottomOptional().orElse( null ) ) );
+		inputSlots.add( Collections.singletonList( recipe.getBottomOptional().orElse( ItemStack.EMPTY ) ) );
 		ingredients.setInputLists( ItemStack.class, inputSlots );
 
 		ingredients.setOutput( ItemStack.class, recipe.getOutput() );

src/main/java/appeng/integration/modules/jei/JEIPlugin.java

@@ -126,7 +126,7 @@ public class JEIPlugin extends BlankModPlugin
 	private void registerGrinderRecipes( IDefinitions definitions, IModRegistry registry )
 	{
 
-		ItemStack grindstone = definitions.blocks().grindstone().maybeStack( 1 ).orElse( null );
+		ItemStack grindstone = definitions.blocks().grindstone().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 		if( grindstone == null )
 		{
@@ -142,19 +142,19 @@ public class JEIPlugin extends BlankModPlugin
 	private void registerCondenserRecipes( IDefinitions definitions, IModRegistry registry )
 	{
 
-		ItemStack condenser = definitions.blocks().condenser().maybeStack( 1 ).orElse( null );
+		ItemStack condenser = definitions.blocks().condenser().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 		if( condenser == null )
 		{
 			return;
 		}
 
-		ItemStack matterBall = definitions.materials().matterBall().maybeStack( 1 ).orElse( null );
+		ItemStack matterBall = definitions.materials().matterBall().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 		if( matterBall != null )
 		{
 			registry.addRecipes( ImmutableList.of( CondenserOutput.MATTER_BALLS ) );
 		}
 
-		ItemStack singularity = definitions.materials().singularity().maybeStack( 1 ).orElse( null );
+		ItemStack singularity = definitions.materials().singularity().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 		if( singularity != null )
 		{
 			registry.addRecipes( ImmutableList.of( CondenserOutput.SINGULARITY ) );

src/main/java/appeng/items/materials/ItemMaterial.java

@@ -220,7 +220,7 @@ public final class ItemMaterial extends AEBaseItem implements IStorageComponent,
 					{
 						for( final ItemStack is : options )
 						{
-							if( is != null && is.getItem() != null )
+							if( !is.isEmpty() && is.getItem() != null )
 							{
 								replacement = is.copy();
 								break;
@@ -301,7 +301,7 @@ public final class ItemMaterial extends AEBaseItem implements IStorageComponent,
 				upgrades = ( (ISegmentedInventory) te ).getInventoryByName( "upgrades" );
 			}
 
-			if( upgrades != null && player.getHeldItemMainhand() != null && player.getHeldItemMainhand().getItem() instanceof IUpgradeModule )
+			if( upgrades != null && !player.getHeldItemMainhand().isEmpty() && player.getHeldItemMainhand().getItem() instanceof IUpgradeModule )
 			{
 				final IUpgradeModule um = (IUpgradeModule) player.getHeldItemMainhand().getItem();
 				final Upgrades u = um.getType( player.getHeldItemMainhand() );
@@ -362,7 +362,7 @@ public final class ItemMaterial extends AEBaseItem implements IStorageComponent,
 
 	private String nameOf( final ItemStack is )
 	{
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			return "null";
 		}

src/main/java/appeng/items/misc/ItemEncodedPattern.java

@@ -80,8 +80,8 @@ public class ItemEncodedPattern extends AEBaseItem implements ICraftingPatternIt
 
 			final InventoryPlayer inv = player.inventory;
 
-			ItemStack is = AEApi.instance().definitions().materials().blankPattern().maybeStack( stack.getCount() ).orElse( null );
+			ItemStack is = AEApi.instance().definitions().materials().blankPattern().maybeStack( stack.getCount() ).orElse( ItemStack.EMPTY );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				for( int s = 0; s < player.inventory.getSizeInventory(); s++ )
 				{

src/main/java/appeng/items/storage/ItemBasicStorageCell.java

@@ -237,11 +237,11 @@ public final class ItemBasicStorageCell extends AEBaseItem implements IStorageCe
 				final IItemList<IAEItemStack> list = inv.getAvailableItems( StorageChannel.ITEMS.createList() );
 				if( list.isEmpty() && ia != null )
 				{
-					playerInventory.setInventorySlotContents( playerInventory.currentItem, null );
+					playerInventory.setInventorySlotContents( playerInventory.currentItem, ItemStack.EMPTY );
 
 					// drop core
 					final ItemStack extraB = ia.addItems( this.component.stack( 1 ) );
-					if( extraB != null )
+					if( !extraB.isEmpty() )
 					{
 						player.dropItem( extraB, false );
 					}
@@ -252,7 +252,7 @@ public final class ItemBasicStorageCell extends AEBaseItem implements IStorageCe
 					{
 						final ItemStack upgradeStack = upgradesInventory.getStackInSlot( upgradeIndex );
 						final ItemStack leftStack = ia.addItems( upgradeStack );
-						if( leftStack != null && upgradeStack.getItem() instanceof IUpgradeModule )
+						if( !leftStack.isEmpty() && upgradeStack.getItem() instanceof IUpgradeModule )
 						{
 							player.dropItem( upgradeStack, false );
 						}
@@ -262,7 +262,7 @@ public final class ItemBasicStorageCell extends AEBaseItem implements IStorageCe
 					AEApi.instance().definitions().materials().emptyStorageCell().maybeStack( 1 ).ifPresent( is ->
 					{
 						final ItemStack extraA = ia.addItems( is );
-						if( extraA != null )
+						if( !extraA.isEmpty() )
 						{
 							player.dropItem( extraA, false );
 						}

src/main/java/appeng/items/storage/ItemViewCell.java

@@ -75,7 +75,7 @@ public class ItemViewCell extends AEBaseItem implements ICellWorkbenchItem
 				for( int x = 0; x < upgrades.getSizeInventory(); x++ )
 				{
 					final ItemStack is = upgrades.getStackInSlot( x );
-					if( is != null && is.getItem() instanceof IUpgradeModule )
+					if( !is.isEmpty() && is.getItem() instanceof IUpgradeModule )
 					{
 						final Upgrades u = ( (IUpgradeModule) is.getItem() ).getType( is );
 						if( u != null )
@@ -97,7 +97,7 @@ public class ItemViewCell extends AEBaseItem implements ICellWorkbenchItem
 				for( int x = 0; x < config.getSizeInventory(); x++ )
 				{
 					final ItemStack is = config.getStackInSlot( x );
-					if( is != null )
+					if( !is.isEmpty() )
 					{
 						priorityList.add( AEItemStack.create( is ) );
 					}

src/main/java/appeng/me/cluster/implementations/CraftingCPUCluster.java

@@ -504,14 +504,14 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 					fuzz = fuzz.copy();
 					fuzz.setStackSize( g.getStackSize() );
 					final IAEItemStack ais = this.inventory.extractItems( fuzz, Actionable.SIMULATE, this.machineSrc );
-					final ItemStack is = ais == null ? null : ais.getItemStack();
+					final ItemStack is = ais == null ? ItemStack.EMPTY : ais.getItemStack();
 
-					if( is != null && is.getCount() == g.getStackSize() )
+					if( !is.isEmpty() && is.getCount() == g.getStackSize() )
 					{
 						found = true;
 						break;
 					}
-					else if( is != null )
+					else if( !is.isEmpty() )
 					{
 						g = g.copy();
 						g.decStackSize( is.getCount() );
@@ -526,9 +526,9 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 			else
 			{
 				final IAEItemStack ais = this.inventory.extractItems( g.copy(), Actionable.SIMULATE, this.machineSrc );
-				final ItemStack is = ais == null ? null : ais.getItemStack();
+				final ItemStack is = ais == null ? ItemStack.EMPTY : ais.getItemStack();
 
-				if( is == null || is.getCount() < g.getStackSize() )
+				if( is.isEmpty() || is.getCount() < g.getStackSize() )
 				{
 					return false;
 				}
@@ -693,9 +693,9 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 											if( details.isValidItemForSlot( x, fuzz.getItemStack(), this.getWorld() ) )
 											{
 												final IAEItemStack ais = this.inventory.extractItems( fuzz, Actionable.MODULATE, this.machineSrc );
-												final ItemStack is = ais == null ? null : ais.getItemStack();
+												final ItemStack is = ais == null ? ItemStack.EMPTY : ais.getItemStack();
 
-												if( is != null )
+												if( !is.isEmpty() )
 												{
 													this.postChange( AEItemStack.create( is ), this.machineSrc );
 													ic.setInventorySlotContents( x, is );
@@ -708,9 +708,9 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 									else
 									{
 										final IAEItemStack ais = this.inventory.extractItems( input[x].copy(), Actionable.MODULATE, this.machineSrc );
-										final ItemStack is = ais == null ? null : ais.getItemStack();
+										final ItemStack is = ais == null ? ItemStack.EMPTY : ais.getItemStack();
 
-										if( is != null )
+										if( !is.isEmpty() )
 										{
 											this.postChange( input[x], this.machineSrc );
 											ic.setInventorySlotContents( x, is );
@@ -735,7 +735,7 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 								for( int x = 0; x < ic.getSizeInventory(); x++ )
 								{
 									final ItemStack is = ic.getStackInSlot( x );
-									if( is != null )
+									if( !is.isEmpty() )
 									{
 										this.inventory.injectItems( AEItemStack.create( is ), Actionable.MODULATE, this.machineSrc );
 									}
@@ -764,7 +764,7 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 								for( int x = 0; x < ic.getSizeInventory(); x++ )
 								{
 									final ItemStack output = Platform.getContainerItem( ic.getStackInSlot( x ) );
-									if( output != null )
+									if( !output.isEmpty() )
 									{
 										final IAEItemStack cItem = AEItemStack.create( output );
 										this.postChange( cItem, this.machineSrc );
@@ -797,7 +797,7 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU
 					for( int x = 0; x < ic.getSizeInventory(); x++ )
 					{
 						final ItemStack is = ic.getStackInSlot( x );
-						if( is != null )
+						if( !is.isEmpty() )
 						{
 							this.inventory.injectItems( AEItemStack.create( is ), Actionable.MODULATE, this.machineSrc );
 						}

src/main/java/appeng/me/storage/CellInventoryHandler.java

@@ -62,7 +62,7 @@ public class CellInventoryHandler extends MEInventoryHandler<IAEItemStack> imple
 			for( int x = 0; x < upgrades.getSizeInventory(); x++ )
 			{
 				final ItemStack is = upgrades.getStackInSlot( x );
-				if( is != null && is.getItem() instanceof IUpgradeModule )
+				if( !is.isEmpty() && is.getItem() instanceof IUpgradeModule )
 				{
 					final Upgrades u = ( (IUpgradeModule) is.getItem() ).getType( is );
 					if( u != null )
@@ -84,7 +84,7 @@ public class CellInventoryHandler extends MEInventoryHandler<IAEItemStack> imple
 			for( int x = 0; x < config.getSizeInventory(); x++ )
 			{
 				final ItemStack is = config.getStackInSlot( x );
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					priorityList.add( AEItemStack.create( is ) );
 				}

src/main/java/appeng/me/storage/CreativeCellInventory.java

@@ -43,7 +43,7 @@ public class CreativeCellInventory implements IMEInventoryHandler<IAEItemStack>
 		final CellConfig cc = new CellConfig( o );
 		for( final ItemStack is : cc )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				final IAEItemStack i = AEItemStack.create( is );
 				i.setStackSize( Integer.MAX_VALUE );

src/main/java/appeng/me/storage/MEMonitorIInventory.java

@@ -75,7 +75,7 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 	@Override
 	public IAEItemStack injectItems( final IAEItemStack input, final Actionable type, final BaseActionSource src )
 	{
-		ItemStack out = null;
+		ItemStack out = ItemStack.EMPTY;
 
 		if( type == Actionable.SIMULATE )
 		{
@@ -91,7 +91,7 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 			this.onTick();
 		}
 
-		if( out == null )
+		if( out.isEmpty() )
 		{
 			return null;
 		}
@@ -105,7 +105,7 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 	@Override
 	public IAEItemStack extractItems( final IAEItemStack request, final Actionable type, final BaseActionSource src )
 	{
-		ItemStack out = null;
+		ItemStack out = ItemStack.EMPTY;
 
 		if( type == Actionable.SIMULATE )
 		{
@@ -116,7 +116,7 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 			out = this.adaptor.removeItems( (int) request.getStackSize(), request.getItemStack(), null );
 		}
 
-		if( out == null )
+		if( out.isEmpty() )
 		{
 			return null;
 		}
@@ -154,7 +154,7 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 			high = Math.max( high, is.getSlot() );
 
 			final ItemStack newIS = !is.isExtractable() && this.getMode() == StorageFilter.EXTRACTABLE_ONLY ? null : is.getItemStack();
-			final ItemStack oldIS = old == null ? null : old.itemStack;
+			final ItemStack oldIS = old == null ? ItemStack.EMPTY : old.itemStack;
 
 			if( this.isDifferent( newIS, oldIS ) )
 			{
@@ -177,8 +177,8 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 			}
 			else
 			{
-				final int newSize = ( newIS == null ? 0 : newIS.getCount() );
+				final int newSize = ( newIS.isEmpty() ? 0 : newIS.getCount() );
-				final int diff = newSize - ( oldIS == null ? 0 : oldIS.getCount() );
+				final int diff = newSize - ( oldIS.isEmpty() ? 0 : oldIS.getCount() );
 
 				final IAEItemStack stack = ( old == null || old.aeStack == null ? AEApi.instance().storage().createItemStack( newIS ) : old.aeStack.copy() );
 				if( stack != null )
@@ -227,12 +227,12 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 
 	private boolean isDifferent( final ItemStack a, final ItemStack b )
 	{
-		if( a == b && b == null )
+		if( a == b && b.isEmpty() )
 		{
 			return false;
 		}
 
-		if( ( a == null && b != null ) || ( a != null && b == null ) )
+		if( ( a.isEmpty() && !b.isEmpty() ) || ( !a.isEmpty() && b.isEmpty() ) )
 		{
 			return true;
 		}
@@ -344,9 +344,9 @@ public class MEMonitorIInventory implements IMEMonitor<IAEItemStack>, ITickingMo
 
 		public CachedItemStack( final ItemStack is )
 		{
-			if( is == null )
+			if( is.isEmpty() )
 			{
-				this.itemStack = null;
+				this.itemStack = ItemStack.EMPTY;
 				this.aeStack = null;
 			}
 			else

src/main/java/appeng/parts/CableBusContainer.java

@@ -1052,12 +1052,12 @@ public class CableBusContainer extends CableBusStorage implements AEMultiTile, I
 			{
 				IPart p = this.getPart( side );
 				final ItemStack iss = new ItemStack( def );
-				if( iss == null )
+				if( iss.isEmpty() )
 				{
 					continue;
 				}
 
-				final ItemStack current = p == null ? null : p.getItemStack( PartItemStack.WORLD );
+				final ItemStack current = p == null ? ItemStack.EMPTY : p.getItemStack( PartItemStack.WORLD );
 
 				if( Platform.itemComparisons().isEqualItemType( iss, current ) )
 				{

src/main/java/appeng/parts/automation/PartImportBus.java

@@ -88,7 +88,7 @@ public class PartImportBus extends PartSharedItemBus implements IInventoryDestin
 	@Override
 	public boolean canInsert( final ItemStack stack )
 	{
-		if( stack == null || stack.getItem() == null )
+		if( stack.isEmpty() || stack.getItem() == null )
 		{
 			return false;
 		}
@@ -217,14 +217,14 @@ public class PartImportBus extends PartSharedItemBus implements IInventoryDestin
 
 		if( this.getInstalledUpgrades( Upgrades.FUZZY ) > 0 )
 		{
-			newItems = myAdaptor.removeSimilarItems( toSend, whatToImport == null ? null : whatToImport.getItemStack(), fzMode, this.configDestination( inv ) );
+			newItems = myAdaptor.removeSimilarItems( toSend, whatToImport == null ? ItemStack.EMPTY : whatToImport.getItemStack(), fzMode, this.configDestination( inv ) );
 		}
 		else
 		{
-			newItems = myAdaptor.removeItems( toSend, whatToImport == null ? null : whatToImport.getItemStack(), this.configDestination( inv ) );
+			newItems = myAdaptor.removeItems( toSend, whatToImport == null ? ItemStack.EMPTY : whatToImport.getItemStack(), this.configDestination( inv ) );
 		}
 
-		if( newItems != null )
+		if( !newItems.isEmpty() )
 		{
 			newItems.setCount( (int) ( Math.min( newItems.getCount(),
 					energy.extractAEPower( newItems.getCount(), Actionable.SIMULATE, PowerMultiplier.CONFIG ) ) + 0.01 ) );
@@ -266,7 +266,7 @@ public class PartImportBus extends PartSharedItemBus implements IInventoryDestin
 
 		if( whatToImport == null )
 		{
-			itemStackToImport = null;
+			itemStackToImport = ItemStack.EMPTY;
 		}
 		else
 		{

src/main/java/appeng/parts/automation/PartUpgradeable.java

@@ -141,7 +141,7 @@ public abstract class PartUpgradeable extends PartBasicState implements IAEAppEn
 	{
 		for( final ItemStack is : this.upgrades )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}

src/main/java/appeng/parts/automation/UpgradeInventory.java

@@ -66,7 +66,7 @@ public abstract class UpgradeInventory extends AppEngInternalInventory implement
 	@Override
 	public boolean isItemValidForSlot( final int i, final ItemStack itemstack )
 	{
-		if( itemstack == null )
+		if( itemstack.isEmpty() )
 		{
 			return false;
 		}

src/main/java/appeng/parts/misc/ItemHandlerAdapter.java

@@ -75,7 +75,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 		boolean simulate = ( type == Actionable.SIMULATE );
 
 		// This uses a brute force approach and tries to jam it in every slot the inventory exposes.
-		for( int i = 0; i < slotCount && remaining != null; i++ )
+		for( int i = 0; i < slotCount && !remaining.isEmpty(); i++ )
 		{
 			remaining = itemHandler.insertItem( i, remaining, simulate );
 		}
@@ -103,7 +103,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 		int remainingSize = requestedItemStack.getCount();
 
 		// Use this to gather the requested items
-		ItemStack gathered = null;
+		ItemStack gathered = ItemStack.EMPTY;
 
 		final boolean simulate = ( mode == Actionable.SIMULATE );
 
@@ -125,7 +125,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 			do
 			{
 				extracted = itemHandler.extractItem( i, remainingCurrentSlot, simulate );
-				if( extracted != null )
+				if( !extracted.isEmpty() )
 				{
 					if( extracted.getCount() > remainingCurrentSlot )
 					{
@@ -137,7 +137,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 					}
 
 					// We're just gonna use the first stack we get our hands on as the template for the rest
-					if( gathered == null )
+					if( gathered.isEmpty() )
 					{
 						gathered = extracted;
 					}
@@ -148,7 +148,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 					remainingCurrentSlot -= extracted.getCount();
 				}
 			}
-			while( extracted != null && remainingCurrentSlot > 0 );
+			while( !extracted.isEmpty() && remainingCurrentSlot > 0 );
 
 			remainingSize -= stackSizeCurrentSlot - remainingCurrentSlot;
 
@@ -159,7 +159,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 			}
 		}
 
-		if( gathered != null )
+		if( !gathered.isEmpty() )
 		{
 			if( mode == Actionable.MODULATE )
 			{
@@ -172,6 +172,17 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 		return null;
 	}
 
+
+	private ItemStack getItemStackInCachedSlot ( int pos ) {
+		if( pos > cachedStacks.length )
+			return ItemStack.EMPTY;
+
+		if( cachedStacks[pos] == null )
+			return ItemStack.EMPTY;
+
+		return cachedStacks[pos];
+	}
+
 	@Override
 	public TickRateModulation onTick()
 	{
@@ -189,7 +200,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 		for( int slot = 0; slot < slots; slot++ )
 		{
 			// Save the old stuff
-			ItemStack oldIS = cachedStacks[slot];
+			ItemStack oldIS = getItemStackInCachedSlot(slot);
 			IAEItemStack oldAeIS = cachedAeStacks[slot];
 
 			ItemStack newIS = itemHandler.getStackInSlot( slot );
@@ -198,7 +209,7 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 			{
 				addItemChange( slot, oldAeIS, newIS, changes );
 			}
-			else if( newIS != null && oldIS != null )
+			else if( !newIS.isEmpty() && !oldIS.isEmpty() )
 			{
 				addPossibleStackSizeChange( slot, oldAeIS, newIS, changes );
 			}
@@ -275,12 +286,12 @@ class ItemHandlerAdapter implements IMEInventory<IAEItemStack>, IBaseMonitor<IAE
 
 	private boolean isDifferent( final ItemStack a, final ItemStack b )
 	{
-		if( a == b && b == null )
+		if( a == b && b.isEmpty() )
 		{
 			return false;
 		}
 
-		return a == null || b == null || !Platform.itemComparisons().isSameItem( a, b );
+		return a.isEmpty() || b.isEmpty() || !Platform.itemComparisons().isSameItem( a, b );
 	}
 
 	private void postDifference( Iterable<IAEItemStack> a )

src/main/java/appeng/parts/misc/PartCableAnchor.java

@@ -60,7 +60,7 @@ public class PartCableAnchor implements IPart
 	@PartModels
 	public static final PartModel FACADE_MODELS = new PartModel( false, new ResourceLocation( AppEng.MOD_ID, "part/cable_anchor_short" ) );
 
-	private ItemStack is = null;
+	private ItemStack is = ItemStack.EMPTY;
 	private IPartHost host = null;
 	private AEPartLocation mySide = AEPartLocation.UP;
 

src/main/java/appeng/parts/p2p/PartP2PTunnel.java

@@ -166,7 +166,7 @@ public abstract class PartP2PTunnel<T extends PartP2PTunnel> extends PartBasicSt
 		// AELog.info( "ID:" + id.toString() + " : " + is.getItemDamage() );
 
 		final TunnelType tt = AEApi.instance().registries().p2pTunnel().getTunnelTypeByItem( is );
-		if( is != null && is.getItem() instanceof IMemoryCard )
+		if( !is.isEmpty() && is.getItem() instanceof IMemoryCard )
 		{
 			final IMemoryCard mc = (IMemoryCard) is.getItem();
 			final NBTTagCompound data = mc.getData( is );
@@ -174,7 +174,7 @@ public abstract class PartP2PTunnel<T extends PartP2PTunnel> extends PartBasicSt
 			final ItemStack newType = new ItemStack( data );
 			final long freq = data.getLong( "freq" );
 
-			if( newType != null )
+			if( !newType.isEmpty() )
 			{
 				if( newType.getItem() instanceof IPartItem )
 				{
@@ -219,7 +219,7 @@ public abstract class PartP2PTunnel<T extends PartP2PTunnel> extends PartBasicSt
 			switch( tt )
 			{
 				case LIGHT:
-					newType = parts.p2PTunnelLight().maybeStack( 1 ).orElse( null );
+					newType = parts.p2PTunnelLight().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 					break;
 
 				/*
@@ -232,23 +232,23 @@ public abstract class PartP2PTunnel<T extends PartP2PTunnel> extends PartBasicSt
 				 */
 
 				//case FLUID:
-				//	newType = parts.p2PTunnelLiquids().maybeStack( 1 ).orElse( null );
+				//	newType = parts.p2PTunnelLiquids().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 				//	break;
 
 				//case IC2_POWER:
-				//	newType = parts.p2PTunnelEU().maybeStack( 1 ).orElse( null );
+				//	newType = parts.p2PTunnelEU().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 				//	break;
 
 				case ITEM:
-					newType = parts.p2PTunnelItems().maybeStack( 1 ).orElse( null );
+					newType = parts.p2PTunnelItems().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 					break;
 
 				case ME:
-					newType = parts.p2PTunnelME().maybeStack( 1 ).orElse( null );
+					newType = parts.p2PTunnelME().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 					break;
 
 				case REDSTONE:
-					newType = parts.p2PTunnelRedstone().maybeStack( 1 ).orElse( null );
+					newType = parts.p2PTunnelRedstone().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 					break;
 
 				/*
@@ -303,7 +303,7 @@ public abstract class PartP2PTunnel<T extends PartP2PTunnel> extends PartBasicSt
 	public boolean onPartShiftActivate( final EntityPlayer player, final EnumHand hand, final Vec3d pos )
 	{
 		final ItemStack is = player.inventory.getCurrentItem();
-		if( is != null && is.getItem() instanceof IMemoryCard )
+		if( !is.isEmpty() && is.getItem() instanceof IMemoryCard )
 		{
 			final IMemoryCard mc = (IMemoryCard) is.getItem();
 			final NBTTagCompound data = new NBTTagCompound();

src/main/java/appeng/parts/reporting/AbstractPartTerminal.java

@@ -81,7 +81,7 @@ public abstract class AbstractPartTerminal extends AbstractPartDisplay implement
 
 		for( final ItemStack is : this.viewCell )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}

src/main/java/appeng/parts/reporting/PartConversionMonitor.java

@@ -120,14 +120,14 @@ public class PartConversionMonitor extends AbstractPartMonitor
 							final IAEItemStack insertItem = input.copy();
 							insertItem.setStackSize( targetStack.getCount() );
 							final IAEItemStack failedToInsert = Platform.poweredInsert( energy, cell, insertItem, new PlayerSource( player, this ) );
-							player.inventory.setInventorySlotContents( x, failedToInsert == null ? null : failedToInsert.getItemStack() );
+							player.inventory.setInventorySlotContents( x, failedToInsert == null ? ItemStack.EMPTY : failedToInsert.getItemStack() );
 						}
 					}
 				}
 				else
 				{
 					final IAEItemStack failedToInsert = Platform.poweredInsert( energy, cell, input, new PlayerSource( player, this ) );
-					player.inventory.setInventorySlotContents( player.inventory.currentItem, failedToInsert == null ? null : failedToInsert.getItemStack() );
+					player.inventory.setInventorySlotContents( player.inventory.currentItem, failedToInsert == null ? ItemStack.EMPTY : failedToInsert.getItemStack() );
 				}
 			}
 			catch( final GridAccessException e )
@@ -163,7 +163,7 @@ public class PartConversionMonitor extends AbstractPartMonitor
 					ItemStack newItems = retrieved.getItemStack();
 					final InventoryAdaptor adaptor = InventoryAdaptor.getAdaptor( player, EnumFacing.UP );
 					newItems = adaptor.addItems( newItems );
-					if( newItems != null )
+					if( !newItems.isEmpty() )
 					{
 						final TileEntity te = this.getTile();
 						final List<ItemStack> list = Collections.singletonList( newItems );

src/main/java/appeng/parts/reporting/PartCraftingTerminal.java

@@ -63,7 +63,7 @@ public class PartCraftingTerminal extends AbstractPartTerminal
 
 		for( final ItemStack is : this.craftingGrid )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}

src/main/java/appeng/parts/reporting/PartPatternTerminal.java

@@ -70,7 +70,7 @@ public class PartPatternTerminal extends AbstractPartTerminal
 	{
 		for( final ItemStack is : this.pattern )
 		{
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -125,7 +125,7 @@ public class PartPatternTerminal extends AbstractPartTerminal
 		if( inv == this.pattern && slot == 1 )
 		{
 			final ItemStack is = this.pattern.getStackInSlot( 1 );
-			if( is != null && is.getItem() instanceof ICraftingPatternItem )
+			if( !is.isEmpty() && is.getItem() instanceof ICraftingPatternItem )
 			{
 				final ICraftingPatternItem pattern = (ICraftingPatternItem) is.getItem();
 				final ICraftingPatternDetails details = pattern.getPatternForItem( is, this.getHost().getTile().getWorld() );
@@ -137,13 +137,13 @@ public class PartPatternTerminal extends AbstractPartTerminal
 					for( int x = 0; x < this.crafting.getSizeInventory() && x < details.getInputs().length; x++ )
 					{
 						final IAEItemStack item = details.getInputs()[x];
-						this.crafting.setInventorySlotContents( x, item == null ? null : item.getItemStack() );
+						this.crafting.setInventorySlotContents( x, item == null ? ItemStack.EMPTY : item.getItemStack() );
 					}
 
 					for( int x = 0; x < this.output.getSizeInventory() && x < details.getOutputs().length; x++ )
 					{
 						final IAEItemStack item = details.getOutputs()[x];
-						this.output.setInventorySlotContents( x, item == null ? null : item.getItemStack() );
+						this.output.setInventorySlotContents( x, item == null ? ItemStack.EMPTY : item.getItemStack() );
 					}
 				}
 			}
@@ -163,7 +163,7 @@ public class PartPatternTerminal extends AbstractPartTerminal
 			for( int x = 0; x < this.crafting.getSizeInventory(); x++ )
 			{
 				final ItemStack is = this.crafting.getStackInSlot( x );
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					is.setCount( 1 );
 				}

src/main/java/appeng/recipes/game/DisassembleRecipe.java

@@ -90,7 +90,7 @@ public final class DisassembleRecipe implements IRecipe
 		for( int slotIndex = 0; slotIndex < inventory.getSizeInventory(); slotIndex++ )
 		{
 			final ItemStack stackInSlot = inventory.getStackInSlot( slotIndex );
-			if( stackInSlot != null )
+			if( !stackInSlot.isEmpty() )
 			{
 				// needs a single input in the recipe
 				itemCount++;

src/main/java/appeng/recipes/game/FacadeRecipe.java

@@ -57,7 +57,7 @@ public final class FacadeRecipe implements IRecipe
 	@Nullable
 	private ItemStack getOutput( final IInventory inv, final boolean createFacade )
 	{
-		if( inv.getStackInSlot( 0 ) == null && inv.getStackInSlot( 2 ) == null && inv.getStackInSlot( 6 ) == null && inv.getStackInSlot( 8 ) == null )
+		if( inv.getStackInSlot( 0 ).isEmpty() && inv.getStackInSlot( 2 ).isEmpty() && inv.getStackInSlot( 6 ).isEmpty() && inv.getStackInSlot( 8 ).isEmpty() )
 		{
 			if( this.anchor.isSameAs( inv.getStackInSlot( 1 ) ) && this.anchor.isSameAs( inv.getStackInSlot( 3 ) ) && this.anchor.isSameAs( inv.getStackInSlot( 5 ) ) && this.anchor.isSameAs( inv.getStackInSlot( 7 ) ) )
 			{

src/main/java/appeng/recipes/game/ShapedRecipe.java

@@ -42,7 +42,7 @@ public class ShapedRecipe implements IRecipe, IRecipeBakeable
 	private static final int MAX_CRAFT_GRID_WIDTH = 3;
 	private static final int MAX_CRAFT_GRID_HEIGHT = 3;
 
-	private ItemStack output = null;
+	private ItemStack output = ItemStack.EMPTY;
 	private Object[] input = null;
 	private int width = 0;
 	private int height = 0;
@@ -256,7 +256,7 @@ public class ShapedRecipe implements IRecipe, IRecipeBakeable
 						return false;
 					}
 				}
-				else if( target == null && slot != null )
+				else if( target == null && !slot.isEmpty() )
 				{
 					return false;
 				}
@@ -268,7 +268,7 @@ public class ShapedRecipe implements IRecipe, IRecipeBakeable
 
 	private boolean checkItemEquals( final ItemStack target, final ItemStack input )
 	{
-		if( input == null && target != null || input != null && target == null )
+		if( input.isEmpty() && !target.isEmpty() || !input.isEmpty() && target.isEmpty() )
 		{
 			return false;
 		}

src/main/java/appeng/recipes/game/ShapelessRecipe.java

@@ -38,7 +38,7 @@ public class ShapelessRecipe implements IRecipe, IRecipeBakeable
 {
 
 	private final ArrayList<Object> input = new ArrayList<Object>();
-	private ItemStack output = null;
+	private ItemStack output = ItemStack.EMPTY;
 	private boolean disable = false;
 
 	public ShapelessRecipe( final ItemStack result, final Object... recipe )
@@ -83,7 +83,7 @@ public class ShapelessRecipe implements IRecipe, IRecipeBakeable
 		{
 			final ItemStack slot = var1.getStackInSlot( x );
 
-			if( slot != null )
+			if( !slot.isEmpty() )
 			{
 				boolean inRecipe = false;
 

src/main/java/appeng/recipes/handlers/Inscribe.java

@@ -59,8 +59,8 @@ public final class Inscribe extends InscriberProcess
 		final ItemStack[] realInput = this.getImprintable().getItemStackSet();
 		final List<ItemStack> inputs = new ArrayList<ItemStack>( realInput.length );
 		Collections.addAll( inputs, realInput );
-		final ItemStack top = ( this.getTopOptional() == null ) ? null : this.getTopOptional().getItemStack();
+		final ItemStack top = ( this.getTopOptional() == null ) ? ItemStack.EMPTY : this.getTopOptional().getItemStack();
-		final ItemStack bot = ( this.getBotOptional() == null ) ? null : this.getBotOptional().getItemStack();
+		final ItemStack bot = ( this.getBotOptional() == null ) ? ItemStack.EMPTY : this.getBotOptional().getItemStack();
 		final ItemStack output = this.getOutput().getItemStack();
 		final InscriberProcessType type = InscriberProcessType.INSCRIBE;
 

src/main/java/appeng/recipes/handlers/Press.java

@@ -59,8 +59,8 @@ public final class Press extends InscriberProcess
 		final ItemStack[] realInput = this.getImprintable().getItemStackSet();
 		final List<ItemStack> inputs = new ArrayList<ItemStack>( realInput.length );
 		Collections.addAll( inputs, realInput );
-		final ItemStack top = ( this.getTopOptional() == null ) ? null : this.getTopOptional().getItemStack();
+		final ItemStack top = ( this.getTopOptional() == null ) ? ItemStack.EMPTY : this.getTopOptional().getItemStack();
-		final ItemStack bot = ( this.getBotOptional() == null ) ? null : this.getBotOptional().getItemStack();
+		final ItemStack bot = ( this.getBotOptional() == null ) ? ItemStack.EMPTY : this.getBotOptional().getItemStack();
 		final ItemStack output = this.getOutput().getItemStack();
 		final InscriberProcessType type = InscriberProcessType.PRESS;
 

src/main/java/appeng/server/ServerHelper.java

@@ -176,7 +176,7 @@ public class ServerHelper extends CommonHelper
 			{
 				final ItemStack is = player.inventory.getStackInSlot( x );
 
-				if( is != null && is.getItem() instanceof ToolNetworkTool )
+				if( !is.isEmpty() && is.getItem() instanceof ToolNetworkTool )
 				{
 					final NBTTagCompound c = is.getTagCompound();
 					if( c != null && c.getBoolean( "hideFacades" ) )

src/main/java/appeng/tile/AEBaseInvTile.java

@@ -81,7 +81,7 @@ public abstract class AEBaseInvTile extends AEBaseTile implements ISidedInventor
 		{
 			final NBTTagCompound item = new NBTTagCompound();
 			final ItemStack is = this.getStackInSlot( x );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				is.writeToNBT( item );
 			}

src/main/java/appeng/tile/AEBaseTile.java

@@ -541,7 +541,7 @@ public class AEBaseTile extends TileEntity implements IOrientable, ICommonTile,
 			for( int l = 0; l < inv.getSizeInventory(); l++ )
 			{
 				final ItemStack is = inv.getStackInSlot( l );
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					drops.add( is );
 				}

src/main/java/appeng/tile/crafting/TileMolecularAssembler.java

@@ -87,7 +87,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 	private final UpgradeInventory upgrades;
 	private boolean isPowered = false;
 	private AEPartLocation pushDirection = AEPartLocation.INTERNAL;
-	private ItemStack myPattern = null;
+	private ItemStack myPattern = ItemStack.EMPTY;
 	private ICraftingPatternDetails myPlan = null;
 	private double progress = 0;
 	private boolean isAwake = false;
@@ -114,12 +114,12 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 	@Override
 	public boolean pushPattern( final ICraftingPatternDetails patternDetails, final InventoryCrafting table, final EnumFacing where )
 	{
-		if( this.myPattern == null )
+		if( this.myPattern.isEmpty() )
 		{
 			boolean isEmpty = true;
 			for( int x = 0; x < this.inv.getSizeInventory(); x++ )
 			{
-				isEmpty = this.inv.getStackInSlot( x ) == null && isEmpty;
+				isEmpty = this.inv.getStackInSlot( x ).isEmpty() && isEmpty;
 			}
 
 			if( isEmpty && patternDetails.isCraftable() )
@@ -167,7 +167,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 	private boolean canPush()
 	{
-		return this.inv.getStackInSlot( 9 ) != null;
+		return !this.inv.getStackInSlot( 9 ).isEmpty();
 	}
 
 	private boolean hasMats()
@@ -182,13 +182,13 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 			this.craftingInv.setInventorySlotContents( x, this.inv.getStackInSlot( x ) );
 		}
 
-		return this.myPlan.getOutput( this.craftingInv, this.getWorld() ) != null;
+		return !this.myPlan.getOutput( this.craftingInv, this.getWorld() ).isEmpty();
 	}
 
 	@Override
 	public boolean acceptsPlans()
 	{
-		return this.inv.getStackInSlot( 10 ) == null;
+		return this.inv.getStackInSlot( 10 ).isEmpty();
 	}
 
 	@Override
@@ -217,7 +217,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 		if( this.forcePlan && this.myPlan != null )
 		{
 			final ItemStack pattern = this.myPlan.getPattern();
-			if( pattern != null )
+			if( !pattern.isEmpty() )
 			{
 				final NBTTagCompound compound = new NBTTagCompound();
 				pattern.writeToNBT( compound );
@@ -238,7 +238,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 		{
 			final ItemStack myPat = new ItemStack( data.getCompoundTag( "myPlan" ) );
 
-			if( myPat != null && myPat.getItem() instanceof ItemEncodedPattern )
+			if( !myPat.isEmpty() && myPat.getItem() instanceof ItemEncodedPattern )
 			{
 				final World w = this.getWorld();
 				final ItemEncodedPattern iep = (ItemEncodedPattern) myPat.getItem();
@@ -269,7 +269,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 		final ItemStack is = this.inv.getStackInSlot( 10 );
 
-		if( is != null && is.getItem() instanceof ItemEncodedPattern )
+		if( !is.isEmpty() && is.getItem() instanceof ItemEncodedPattern )
 		{
 			if( !Platform.itemComparisons().isEqualItem( is, this.myPattern ) )
 			{
@@ -290,7 +290,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 			this.progress = 0;
 			this.forcePlan = false;
 			this.myPlan = null;
-			this.myPattern = null;
+			this.myPattern = ItemStack.EMPTY;
 			this.pushDirection = AEPartLocation.INTERNAL;
 		}
 
@@ -367,7 +367,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 	private boolean hasPattern()
 	{
-		return this.myPlan != null && this.inv.getStackInSlot( 10 ) != null;
+		return this.myPlan != null && !this.inv.getStackInSlot( 10 ).isEmpty();
 	}
 
 	@Override
@@ -404,7 +404,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 		for( int h = 0; h < this.upgrades.getSizeInventory(); h++ )
 		{
 			final ItemStack is = this.upgrades.getStackInSlot( h );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -422,12 +422,12 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 	@Override
 	public TickRateModulation tickingRequest( final IGridNode node, int ticksSinceLastCall )
 	{
-		if( this.inv.getStackInSlot( 9 ) != null )
+		if( !this.inv.getStackInSlot( 9 ).isEmpty() )
 		{
 			this.pushOut( this.inv.getStackInSlot( 9 ) );
 
 			// did it eject?
-			if( this.inv.getStackInSlot( 9 ) == null )
+			if( this.inv.getStackInSlot( 9 ).isEmpty() )
 			{
 				this.markDirty();
 			}
@@ -487,7 +487,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 			this.progress = 0;
 			final ItemStack output = this.myPlan.getOutput( this.craftingInv, this.getWorld() );
-			if( output != null )
+			if( !output.isEmpty() )
 			{
 				FMLCommonHandler.instance().firePlayerCraftingEvent( Platform.getPlayer( (WorldServer) this.getWorld() ), output, this.craftingInv );
 
@@ -498,7 +498,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 					this.inv.setInventorySlotContents( x, Platform.getContainerItem( this.craftingInv.getStackInSlot( x ) ) );
 				}
 
-				if( this.inv.getStackInSlot( 10 ) == null )
+				if( this.inv.getStackInSlot( 10 ).isEmpty() )
 				{
 					this.forcePlan = false;
 					this.myPlan = null;
@@ -529,17 +529,17 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 	private void ejectHeldItems()
 	{
-		if( this.inv.getStackInSlot( 9 ) == null )
+		if( this.inv.getStackInSlot( 9 ).isEmpty() )
 		{
 			for( int x = 0; x < 9; x++ )
 			{
 				final ItemStack is = this.inv.getStackInSlot( x );
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					if( this.myPlan == null || !this.myPlan.isValidItemForSlot( x, is, this.world ) )
 					{
 						this.inv.setInventorySlotContents( 9, is );
-						this.inv.setInventorySlotContents( x, null );
+						this.inv.setInventorySlotContents( x, ItemStack.EMPTY );
 						this.markDirty();
 						return;
 					}
@@ -574,7 +574,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 			output = this.pushTo( output, this.pushDirection.getFacing() );
 		}
 
-		if( output == null && this.forcePlan )
+		if( output.isEmpty() && this.forcePlan )
 		{
 			this.forcePlan = false;
 			this.recalculatePlan();
@@ -585,7 +585,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 	private ItemStack pushTo( ItemStack output, final EnumFacing d )
 	{
-		if( output == null )
+		if( output.isEmpty() )
 		{
 			return output;
 		}
@@ -606,7 +606,7 @@ public class TileMolecularAssembler extends AENetworkInvTile implements IUpgrade
 
 		final int size = output.getCount();
 		output = adaptor.addItems( output );
-		final int newSize = output == null ? 0 : output.getCount();
+		final int newSize = output.isEmpty() ? 0 : output.getCount();
 
 		if( size != newSize )
 		{

src/main/java/appeng/tile/grindstone/TileGrinder.java

@@ -177,7 +177,7 @@ public class TileGrinder extends AEBaseInvTile implements ICrankable
 				}
 			} );
 
-			this.setInventorySlotContents( 6, null );
+			this.setInventorySlotContents( 6, ItemStack.EMPTY );
 		}
 	}
 
@@ -189,7 +189,7 @@ public class TileGrinder extends AEBaseInvTile implements ICrankable
 		}
 
 		final ItemStack notAdded = sia.addItems( output );
-		if( notAdded != null )
+		if( !notAdded.isEmpty() )
 		{
 			final List<ItemStack> out = new ArrayList<ItemStack>();
 			out.add( notAdded );

src/main/java/appeng/tile/inventory/AppEngInternalAEInventory.java

@@ -56,7 +56,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 	{
 		for( int x = 0; x < this.size; x++ )
 		{
-			if( this.getStackInSlot( x ) != null )
+			if( !this.getStackInSlot( x ).isEmpty() )
 			{
 				return false;
 			}
@@ -142,7 +142,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 	{
 		if( this.inv[var1] == null )
 		{
-			return null;
+			return ItemStack.EMPTY;
 		}
 
 		return this.inv[var1].getItemStack();
@@ -154,7 +154,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 		if( this.inv[slot] != null )
 		{
 			final ItemStack split = this.getStackInSlot( slot );
-			ItemStack ns = null;
+			ItemStack ns = ItemStack.EMPTY;
 
 			if( qty >= split.getCount() )
 			{
@@ -168,7 +168,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 
 			if( this.te != null && Platform.isServer() )
 			{
-				this.te.onChangeInventory( this, slot, InvOperation.decreaseStackSize, ns, null );
+				this.te.onChangeInventory( this, slot, InvOperation.decreaseStackSize, ns, ItemStack.EMPTY );
 			}
 
 			return ns;
@@ -194,23 +194,23 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 			ItemStack removed = oldStack;
 			ItemStack added = newItemStack;
 
-			if( oldStack != null && newItemStack != null && Platform.itemComparisons().isEqualItem( oldStack, newItemStack ) )
+			if( !oldStack.isEmpty() && !newItemStack.isEmpty() && Platform.itemComparisons().isEqualItem( oldStack, newItemStack ) )
 			{
 				if( oldStack.getCount() > newItemStack.getCount() )
 				{
 					removed = removed.copy();
 					removed.grow( -newItemStack.getCount() );
-					added = null;
+					added = ItemStack.EMPTY;
 				}
 				else if( oldStack.getCount() < newItemStack.getCount() )
 				{
 					added = added.copy();
 					added.grow( -oldStack.getCount() );
-					removed = null;
+					removed = ItemStack.EMPTY;
 				}
 				else
 				{
-					removed = added = null;
+					removed = added = ItemStack.EMPTY;
 				}
 			}
 
@@ -241,7 +241,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 	{
 		if( this.te != null && Platform.isServer() )
 		{
-			this.te.onChangeInventory( this, -1, InvOperation.markDirty, null, null );
+			this.te.onChangeInventory( this, -1, InvOperation.markDirty, ItemStack.EMPTY, ItemStack.EMPTY );
 		}
 	}
 
@@ -309,7 +309,7 @@ public class AppEngInternalAEInventory implements IInventory, Iterable<ItemStack
 	{
 		for( int x = 0; x < this.size; x++ )
 		{
-			this.setInventorySlotContents( x, null );
+			this.setInventorySlotContents( x, ItemStack.EMPTY );
 		}
 	}
 }

src/main/java/appeng/tile/inventory/AppEngInternalInventory.java

@@ -69,7 +69,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 	@Override
 	public ItemStack getStackInSlot( final int var1 )
 	{
-		return this.inv[var1];
+		return this.inv[var1] == null ? ItemStack.EMPTY : this.inv[var1];
 	}
 
 	@Override
@@ -78,12 +78,12 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 		if( this.inv[slot] != null )
 		{
 			final ItemStack split = this.getStackInSlot( slot );
-			ItemStack ns = null;
+			ItemStack ns = ItemStack.EMPTY;
 
 			if( qty >= split.getCount() )
 			{
 				ns = this.inv[slot];
-				this.inv[slot] = null;
+				this.inv[slot] = ItemStack.EMPTY;
 			}
 			else
 			{
@@ -92,7 +92,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 
 			if( this.getTileEntity() != null && this.eventsEnabled() )
 			{
-				this.getTileEntity().onChangeInventory( this, slot, InvOperation.decreaseStackSize, ns, null );
+				this.getTileEntity().onChangeInventory( this, slot, InvOperation.decreaseStackSize, ns, ItemStack.EMPTY );
 			}
 
 			this.markDirty();
@@ -124,7 +124,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 			ItemStack removed = oldStack;
 			ItemStack added = newItemStack;
 
-			if( oldStack != null && newItemStack != null && Platform.itemComparisons().isEqualItem( oldStack, newItemStack ) )
+			if( !oldStack.isEmpty() && !newItemStack.isEmpty() && Platform.itemComparisons().isEqualItem( oldStack, newItemStack ) )
 			{
 				if( oldStack.getCount() > newItemStack.getCount() )
 				{
@@ -136,11 +136,11 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 				{
 					added = added.copy();
 					added.grow( -oldStack.getCount() );
-					removed = null;
+					removed = ItemStack.EMPTY;
 				}
 				else
 				{
-					removed = added = null;
+					removed = added = ItemStack.EMPTY;
 				}
 			}
 
@@ -173,7 +173,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 	{
 		if( this.getTileEntity() != null && this.eventsEnabled() )
 		{
-			this.getTileEntity().onChangeInventory( this, -1, InvOperation.markDirty, null, null );
+			this.getTileEntity().onChangeInventory( this, -1, InvOperation.markDirty, ItemStack.EMPTY, ItemStack.EMPTY );
 		}
 	}
 
@@ -199,7 +199,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 	{
 		if( this.getTileEntity() != null && this.eventsEnabled() )
 		{
-			this.getTileEntity().onChangeInventory( this, slotIndex, InvOperation.markDirty, null, null );
+			this.getTileEntity().onChangeInventory( this, slotIndex, InvOperation.markDirty, ItemStack.EMPTY, ItemStack.EMPTY );
 		}
 	}
 
@@ -306,7 +306,7 @@ public class AppEngInternalInventory implements IInventory, Iterable<ItemStack>
 	{
 		for( int x = 0; x < this.size; x++ )
 		{
-			this.setInventorySlotContents( x, null );
+			this.setInventorySlotContents( x, ItemStack.EMPTY );
 		}
 	}
 

src/main/java/appeng/tile/misc/TileCellWorkbench.java

@@ -72,7 +72,7 @@ public class TileCellWorkbench extends AEBaseTile implements IUpgradeableHost, I
 			}
 
 			final ItemStack is = this.cell.getStackInSlot( 0 );
-			if( is == null )
+			if( is.isEmpty() )
 			{
 				return null;
 			}
@@ -90,7 +90,7 @@ public class TileCellWorkbench extends AEBaseTile implements IUpgradeableHost, I
 
 	public ICellWorkbenchItem getCell()
 	{
-		if( this.cell.getStackInSlot( 0 ) == null )
+		if( this.cell.getStackInSlot( 0 ).isEmpty() )
 		{
 			return null;
 		}
@@ -157,7 +157,7 @@ public class TileCellWorkbench extends AEBaseTile implements IUpgradeableHost, I
 				boolean cellHasConfig = false;
 				for( int x = 0; x < configInventory.getSizeInventory(); x++ )
 				{
-					if( configInventory.getStackInSlot( x ) != null )
+					if( !configInventory.getStackInSlot( x ).isEmpty() )
 					{
 						cellHasConfig = true;
 						break;
@@ -185,7 +185,7 @@ public class TileCellWorkbench extends AEBaseTile implements IUpgradeableHost, I
 			{
 				for( int x = 0; x < this.config.getSizeInventory(); x++ )
 				{
-					this.config.setInventorySlotContents( x, null );
+					this.config.setInventorySlotContents( x, ItemStack.EMPTY );
 				}
 
 				this.markDirty();
@@ -219,7 +219,7 @@ public class TileCellWorkbench extends AEBaseTile implements IUpgradeableHost, I
 			}
 
 			final ItemStack is = this.cell.getStackInSlot( 0 );
-			if( is == null )
+			if( is.isEmpty() )
 			{
 				return null;
 			}

src/main/java/appeng/tile/misc/TileCharger.java

@@ -93,7 +93,7 @@ public class TileCharger extends AENetworkPowerTile implements ICrankable, IGrid
 		}
 		catch( final Throwable t )
 		{
-			this.inv.setInventorySlotContents( 0, null );
+			this.inv.setInventorySlotContents( 0, ItemStack.EMPTY );
 		}
 		return false; // TESR doesn't need updates!
 	}
@@ -217,7 +217,7 @@ public class TileCharger extends AENetworkPowerTile implements ICrankable, IGrid
 		}
 
 		final ItemStack myItem = this.getStackInSlot( 0 );
-		if( myItem == null )
+		if( myItem.isEmpty() )
 		{
 			ItemStack held = player.inventory.getCurrentItem();
 
@@ -231,7 +231,7 @@ public class TileCharger extends AENetworkPowerTile implements ICrankable, IGrid
 		{
 			final List<ItemStack> drops = new ArrayList<ItemStack>();
 			drops.add( myItem );
-			this.setInventorySlotContents( 0, null );
+			this.setInventorySlotContents( 0, ItemStack.EMPTY );
 			Platform.spawnDrops( this.world, this.pos.offset( this.getForward() ), drops );
 		}
 	}
@@ -267,7 +267,7 @@ public class TileCharger extends AENetworkPowerTile implements ICrankable, IGrid
 			return true;
 		}
 
-		if( myItem == null )
+		if( myItem.isEmpty() )
 		{
 			return false;
 		}

src/main/java/appeng/tile/misc/TileCondenser.java

@@ -97,7 +97,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 	public double getStorage()
 	{
 		final ItemStack is = this.inv.getStackInSlot( 2 );
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			if( is.getItem() instanceof IStorageComponent )
 			{
@@ -118,7 +118,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 
 		final double requiredPower = this.getRequiredPower();
 		final ItemStack output = this.getOutput();
-		while( requiredPower <= this.getStoredPower() && output != null && requiredPower > 0 )
+		while( requiredPower <= this.getStoredPower() && !output.isEmpty()  && requiredPower > 0 )
 		{
 			if( this.canAddOutput( output ) )
 			{
@@ -135,7 +135,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 	private boolean canAddOutput( final ItemStack output )
 	{
 		final ItemStack outputStack = this.getStackInSlot( 1 );
-		return outputStack == null || ( Platform.itemComparisons().isEqualItem( outputStack,
+		return outputStack.isEmpty() || ( Platform.itemComparisons().isEqualItem( outputStack,
 				output ) && outputStack.getCount() < outputStack.getMaxStackSize() );
 	}
 
@@ -147,7 +147,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 	private void addOutput( final ItemStack output )
 	{
 		final ItemStack outputStack = this.getStackInSlot( 1 );
-		if( outputStack == null )
+		if( outputStack.isEmpty() )
 		{
 			this.setInventorySlotContents( 1, output.copy() );
 		}
@@ -165,10 +165,10 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 		switch( (CondenserOutput) this.cm.getSetting( Settings.CONDENSER_OUTPUT ) )
 		{
 			case MATTER_BALLS:
-				return materials.matterBall().maybeStack( 1 ).orElse( null );
+				return materials.matterBall().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			case SINGULARITY:
-				return materials.singularity().maybeStack( 1 ).orElse( null );
+				return materials.singularity().maybeStack( 1 ).orElse( ItemStack.EMPTY );
 
 			case TRASH:
 			default:
@@ -192,7 +192,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 	{
 		if( i == 0 )
 		{
-			if( itemstack != null )
+			if( !itemstack.isEmpty() )
 			{
 				this.addPower( itemstack.getCount() );
 			}
@@ -215,10 +215,10 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 		if( slot == 0 )
 		{
 			final ItemStack is = inv.getStackInSlot( 0 );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				this.addPower( is.getCount() );
-				inv.setInventorySlotContents( 0, null );
+				inv.setInventorySlotContents( 0, ItemStack.EMPTY );
 			}
 		}
 	}
@@ -324,7 +324,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 			{
 				return stack;
 			}
-			if( !simulate && stack != null )
+			if( !simulate && !stack.isEmpty() )
 			{
 				addPower( stack.getCount() );
 			}

src/main/java/appeng/tile/misc/TileInscriber.java

@@ -168,7 +168,7 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 			}
 			else
 			{
-				this.inv.setInventorySlotContents( num, null );
+				this.inv.setInventorySlotContents( num, ItemStack.EMPTY );
 			}
 		}
 
@@ -215,7 +215,7 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 		for( int h = 0; h < this.upgrades.getSizeInventory(); h++ )
 		{
 			final ItemStack is = this.upgrades.getStackInSlot( h );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				drops.add( is );
 			}
@@ -344,17 +344,17 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 		final ItemStack plateB = this.getStackInSlot( 1 );
 		ItemStack renamedItem = this.getStackInSlot( 2 );
 
-		if( plateA != null && plateA.getCount() > 1 )
+		if( !plateA.isEmpty() && plateA.getCount() > 1 )
 		{
 			return null;
 		}
 
-		if( plateB != null && plateB.getCount() > 1 )
+		if( !plateB.isEmpty() && plateB.getCount() > 1 )
 		{
 			return null;
 		}
 
-		if( renamedItem != null && renamedItem.getCount() > 1 )
+		if( !renamedItem.isEmpty() && renamedItem.getCount() > 1 )
 		{
 			return null;
 		}
@@ -363,19 +363,19 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 		final boolean isNameA = namePress.isSameAs( plateA );
 		final boolean isNameB = namePress.isSameAs( plateB );
 
-		if( ( isNameA || isNameB ) && ( isNameA || plateA == null ) && ( isNameB || plateB == null ) )
+		if( ( isNameA || isNameB ) && ( isNameA || plateA.isEmpty() ) && ( isNameB || plateB.isEmpty() ) )
 		{
-			if( renamedItem != null )
+			if( !renamedItem.isEmpty() )
 			{
 				String name = "";
 
-				if( plateA != null )
+				if( !plateA.isEmpty() )
 				{
 					final NBTTagCompound tag = Platform.openNbtData( plateA );
 					name += tag.getString( "InscribeName" );
 				}
 
-				if( plateB != null )
+				if( !plateB.isEmpty() )
 				{
 					final NBTTagCompound tag = Platform.openNbtData( plateB );
 					if( name.length() > 0 )
@@ -417,15 +417,15 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 		for( final IInscriberRecipe recipe : AEApi.instance().registries().inscriber().getRecipes() )
 		{
 
-			final boolean matchA = ( plateA == null && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( plateA,
+			final boolean matchA = ( plateA.isEmpty() && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( plateA,
-					recipe.getTopOptional().orElse( null ) ) ) && // and...
+					recipe.getTopOptional().orElse( ItemStack.EMPTY ) ) ) && // and...
-					( plateB == null && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( plateB,
+					( plateB.isEmpty() && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( plateB,
-							recipe.getBottomOptional().orElse( null ) ) );
+							recipe.getBottomOptional().orElse( ItemStack.EMPTY ) ) );
 
-			final boolean matchB = ( plateB == null && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( plateB,
+			final boolean matchB = ( plateB.isEmpty() && !recipe.getTopOptional().isPresent() ) || ( Platform.itemComparisons().isSameItem( plateB,
-					recipe.getTopOptional().orElse( null ) ) ) && // and...
+					recipe.getTopOptional().orElse( ItemStack.EMPTY ) ) ) && // and...
-					( plateA == null && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( plateA,
+					( plateA.isEmpty() && !recipe.getBottomOptional().isPresent() ) | ( Platform.itemComparisons().isSameItem( plateA,
-							recipe.getBottomOptional().orElse( null ) ) );
+							recipe.getBottomOptional().orElse( ItemStack.EMPTY ) ) );
 
 			if( matchA || matchB )
 			{
@@ -455,15 +455,15 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 					final ItemStack outputCopy = out.getOutput().copy();
 					final InventoryAdaptor ad = InventoryAdaptor.getAdaptor( new WrapperInventoryRange( this.inv, SLOT_OUT, 1, true ), EnumFacing.UP );
 
-					if( ad.addItems( outputCopy ) == null )
+					if( ad.addItems( outputCopy ).isEmpty() )
 					{
 						this.setProcessingTime( 0 );
 						if( out.getProcessType() == InscriberProcessType.PRESS )
 						{
-							this.setInventorySlotContents( SLOT_TOP, null );
+							this.setInventorySlotContents( SLOT_TOP, ItemStack.EMPTY );
-							this.setInventorySlotContents( SLOT_BOTTOM, null );
+							this.setInventorySlotContents( SLOT_BOTTOM, ItemStack.EMPTY );
 						}
-						this.setInventorySlotContents( SLOT_MIDDLE, null );
+						this.setInventorySlotContents( SLOT_MIDDLE, ItemStack.EMPTY );
 					}
 				}
 
@@ -522,7 +522,7 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 				{
 					final ItemStack outputCopy = out.getOutput().copy();
 					final InventoryAdaptor ad = InventoryAdaptor.getAdaptor( new WrapperInventoryRange( this.inv, SLOT_OUT, 1, true ), EnumFacing.UP );
-					if( ad.simulateAdd( outputCopy ) == null )
+					if( ad.simulateAdd( outputCopy ).isEmpty() )
 					{
 						this.setSmash( true );
 						this.finalStep = 0;
@@ -678,13 +678,13 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 		@Override
 		public ItemStack insertItem( int slot, ItemStack stack, boolean simulate )
 		{
-			if( slot != 0 || stack == null )
+			if( slot != 0 || stack.isEmpty() )
 			{
 				return stack;
 			}
 
 			// If there's already an item stack in the slot, we don't allow insertion and don't do any other checks
-			if( inv.getStackInSlot( insertSlot ) != null )
+			if( !inv.getStackInSlot( insertSlot ).isEmpty() )
 			{
 				return stack;
 			}
@@ -715,11 +715,11 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 
 			if( simulate )
 			{
-				return adapter.simulateRemove( amount, null, null );
+				return adapter.simulateRemove( amount, ItemStack.EMPTY, null );
 			}
 			else
 			{
-				return adapter.removeItems( amount, null, null );
+				return adapter.removeItems( amount, ItemStack.EMPTY, null );
 			}
 		}
 

src/main/java/appeng/tile/misc/TileVibrationChamber.java

@@ -157,7 +157,7 @@ public class TileVibrationChamber extends AENetworkInvTile implements IGridTicka
 	private boolean canEatFuel()
 	{
 		final ItemStack is = this.getStackInSlot( FUEL_SLOT_INDEX );
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			final int newBurnTime = TileEntityFurnace.getItemBurnTime( is );
 			if( newBurnTime > 0 && is.getCount() > 0 )
@@ -244,7 +244,7 @@ public class TileVibrationChamber extends AENetworkInvTile implements IGridTicka
 	private void eatFuel()
 	{
 		final ItemStack is = this.getStackInSlot( FUEL_SLOT_INDEX );
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			final int newBurnTime = TileEntityFurnace.getItemBurnTime( is );
 			if( newBurnTime > 0 && is.getCount() > 0 )

src/main/java/appeng/tile/qnb/TileQuantumBridge.java

@@ -94,7 +94,7 @@ public class TileQuantumBridge extends AENetworkInvTile implements IAEMultiBlock
 	{
 		int out = this.constructed;
 
-		if( this.getStackInSlot( 0 ) != null && this.constructed != -1 )
+		if( !this.getStackInSlot( 0 ).isEmpty() && this.constructed != -1 )
 		{
 			out |= this.hasSingularity;
 		}
@@ -272,7 +272,7 @@ public class TileQuantumBridge extends AENetworkInvTile implements IAEMultiBlock
 	public long getQEFrequency()
 	{
 		final ItemStack is = this.internalInventory.getStackInSlot( 0 );
-		if( is != null )
+		if( !is.isEmpty() )
 		{
 			final NBTTagCompound c = is.getTagCompound();
 			if( c != null )

src/main/java/appeng/tile/spatial/TileSpatialIOPort.java

@@ -114,7 +114,7 @@ public class TileSpatialIOPort extends AENetworkInvTile implements IWorldCallabl
 
 	private boolean isSpatialCell( final ItemStack cell )
 	{
-		if( cell != null && cell.getItem() instanceof ISpatialStorageCell )
+		if( !cell.isEmpty() && cell.getItem() instanceof ISpatialStorageCell )
 		{
 			final ISpatialStorageCell sc = (ISpatialStorageCell) cell.getItem();
 			return sc != null && sc.isSpatialStorage( cell );
@@ -126,7 +126,7 @@ public class TileSpatialIOPort extends AENetworkInvTile implements IWorldCallabl
 	public Void call( final World world ) throws Exception
 	{
 		final ItemStack cell = this.getStackInSlot( 0 );
-		if( this.isSpatialCell( cell ) && this.getStackInSlot( 1 ) == null )
+		if( this.isSpatialCell( cell ) && this.getStackInSlot( 1 ).isEmpty() )
 		{
 			final IGrid gi = this.getProxy().getGrid();
 			final IEnergyGrid energy = this.getProxy().getEnergy();
@@ -147,7 +147,7 @@ public class TileSpatialIOPort extends AENetworkInvTile implements IWorldCallabl
 						if( tr.success )
 						{
 							energy.extractAEPower( req, Actionable.MODULATE, PowerMultiplier.CONFIG );
-							this.setInventorySlotContents( 0, null );
+							this.setInventorySlotContents( 0, ItemStack.EMPTY );
 							this.setInventorySlotContents( 1, cell );
 						}
 					}

src/main/java/appeng/tile/storage/TileChest.java

@@ -199,7 +199,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 			this.fluidCell = null;
 
 			final ItemStack is = this.inv.getStackInSlot( 1 );
-			if( is != null )
+			if( !is.isEmpty() )
 			{
 				this.isCached = true;
 				this.cellHandler = AEApi.instance().registries().cell().getHandler( is );
@@ -393,7 +393,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 			}
 		}
 
-		if( this.inv.getStackInSlot( 0 ) != null )
+		if( !this.inv.getStackInSlot( 0 ).isEmpty() )
 		{
 			this.tryToStoreContents();
 		}
@@ -430,7 +430,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 
 		final ItemStack is = this.inv.getStackInSlot( 1 );
 
-		if( is == null )
+		if( is.isEmpty() )
 		{
 			data.writeInt( 0 );
 		}
@@ -454,7 +454,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 
 		if( item == 0 )
 		{
-			this.storageType = null;
+			this.storageType = ItemStack.EMPTY;
 		}
 		else
 		{
@@ -616,7 +616,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 	{
 		try
 		{
-			if( this.getStackInSlot( 0 ) != null )
+			if( !this.getStackInSlot( 0 ).isEmpty() )
 			{
 				final IMEInventory<IAEItemStack> cell = this.getHandler( StorageChannel.ITEMS );
 
@@ -624,7 +624,7 @@ public class TileChest extends AENetworkPowerTile implements IMEChest, ITerminal
 
 				if( returns == null )
 				{
-					this.inv.setInventorySlotContents( 0, null );
+					this.inv.setInventorySlotContents( 0, ItemStack.EMPTY );
 				}
 				else
 				{

src/main/java/appeng/tile/storage/TileDrive.java

@@ -312,7 +312,7 @@ public class TileDrive extends AENetworkInvTile implements IChestOrDrive, IPrior
 				this.invBySlot[x] = null;
 				this.handlersBySlot[x] = null;
 
-				if( is != null )
+				if( !is.isEmpty() )
 				{
 					this.handlersBySlot[x] = AEApi.instance().registries().cell().getHandler( is );