Merging ItemStacks that are stored in an ArrayList

[memcallen]

this code isn't working (as in it crashes with NullPointerException):

 

@Override
public void updateTick(World world,int x,int y,int z,Random rand){
	CrucibleTileEntity te = (CrucibleTileEntity)world.getTileEntity(x, y, z);

	List<EntityItem> items = world.getEntitiesWithinAABB(EntityItem.class, AxisAlignedBB.getBoundingBox(x+0D, y+1D, z+0D, x+1D, y+2D, z+1D));

	ItemStack item=null;

	if(items.size()>0){


		item = items.get(items.size()-1).getEntityItem();
		if(CrucibleRecipeHandler.alloweds.contains(item.getItem())){

			int Counter=0;

			for(ItemStack i : inventory){
				Counter++;
				if(i.isItemEqual(item))
					if(i.isItemEqual(inventory.get(Counter-1))){
						inventory.add(new ItemStack(i.getItem(),i.stackSize+inventory.get(Counter-1).stackSize));
						inventory.remove(Counter-1);
					break;
					}
			}
			Counter=0;


			inventory.add(item);
			items.get(items.size()-1).setDead();
			item = null;
		}

 

inventory is an ArrayList stored outside the function. Yes I  realize I have to use a tileentity etc, this is just for testing purposes.

[memcallen]

I changed it to:

item = items.get(items.size()-1).getEntityItem();
		if(CrucibleRecipeHandler.alloweds.contains(item.getItem())){

			int Counter=0;

			for(ItemStack i : inventory){
				Counter++;
				if(i.isItemEqual(item))
					if(inventory.get(Counter)!=null)
					if(i.isItemEqual(inventory.get(Counter-1))){
						inventory.add(new ItemStack(i.getItem(),i.stackSize+inventory.get(Counter-1).stackSize));
					break;
					}
			}
			if(inventory.get(Counter-1)!=null)
			inventory.remove(Counter-1);
			Counter=0;


			inventory.add(item);
			items.get(items.size()-1).setDead();
			item = null;
		}

it still doesn't work, keep getting crashes on my null check... "if(inventory.get(Counter-1)!=null)"

[memcallen]

same as before

[MrCaracal]

Is your inventory ArrayList ever empty for any reason?

 

If so, then it will crash on that line since you're checking the index position of Counter-1, which will be -1 if the counter is not incremented. Now, the counter is only incremented within your augmented for-loop, which won't execute if there are no elements in the inventory ArrayList.

[memcallen]

So I have to redo it pretty much...

[memcallen]

Should I still try and use an ArrayList? or should I just use an ItemStack[]?

[MuffinMonster]

I'd say you could do a if(inventory != null) check before that get() call.

 

I also see that you do not have brackets for the if-statements, which only works for one-line statements after the if()

[memcallen]

first, wouldn't the ArrayList = a new ArrayList?  Wouldn't it not be null then? or is that how "new" works.

 

also They're nested if statements, I didn't need the brackets.