Added checks for null and equal class to .equals()

Also switched a check for null in OreHelper#sameOre to prevent null ==
null => true

src/main/java/appeng/util/item/AEItemDef.java

@@ -60,8 +60,12 @@ public class AEItemDef
 	@Override
 	public boolean equals(Object obj)
 	{
-		AEItemDef def = (AEItemDef) obj;
-		return def.damageValue == damageValue && def.item == item && tagCompound == def.tagCompound;
+		if ( obj == null )
+			return false;
+		if ( getClass() != obj.getClass() )
+			return false;
+		AEItemDef other = (AEItemDef) obj;
+		return other.damageValue == damageValue && other.item == item && tagCompound == other.tagCompound;
 	}
 
 	public int getDamageValueHack(ItemStack is)

src/main/java/appeng/util/item/OreHelper.java

@@ -16,7 +16,8 @@ public class OreHelper
 	class ItemRef
 	{
 
-		ItemRef(ItemStack stack) {
+		ItemRef(ItemStack stack)
+		{
 			ref = stack.getItem();
 
 			if ( stack.getItem().isDamageable() )
@@ -32,10 +33,14 @@ public class OreHelper
 		int hash;
 
 		@Override
-		public boolean equals(Object o)
+		public boolean equals(Object obj)
 		{
-			ItemRef obj = (ItemRef) o;
-			return damage == obj.damage && ref == obj.ref;
+			if ( obj == null )
+				return false;
+			if ( getClass() != obj.getClass() )
+				return false;
+			ItemRef other = (ItemRef) obj;
+			return damage == other.damage && ref == other.ref;
 		}
 
 		@Override
@@ -103,12 +108,12 @@ public class OreHelper
 		OreReference a = aeItemStack.def.isOre;
 		OreReference b = aeItemStack.def.isOre;
 
-		if ( a == b )
-			return true;
-
 		if ( a == null || b == null )
 			return false;
 
+		if ( a == b )
+			return true;
+
 		Collection<Integer> bOres = b.getOres();
 		for (Integer ore : a.getOres())
 		{

src/main/java/appeng/util/item/SharedSearchObject.java

@@ -23,10 +23,12 @@ public class SharedSearchObject
 	{
 		if ( obj == null )
 			return false;
-		SharedSearchObject b = (SharedSearchObject) obj;
-		if ( def == b.def && hash == b.hash )
+		if ( getClass() != obj.getClass() )
+			return false;
+		SharedSearchObject other = (SharedSearchObject) obj;
+		if ( def == other.def && hash == other.hash )
 		{
-			return Platform.NBTEqualityTest( compound, b.compound );
+			return Platform.NBTEqualityTest( compound, other.compound );
 		}
 		return false;
 	}