[1.12.2] Check for free slot in player inventory

[xorinzor]

So, maybe I'm just trying to cut corners here, but none of these IF-statements seem to be returning true, despite the inventory definitely having empty slots.
 

if(player.inventory.hasItemStack(ItemStack.EMPTY)) {
	//Do something
}

if(player.inventory.hasItemStack(new ItemStack(Items.AIR))) {
	//Do something
}

if(player.inventory.hasItemStack(new ItemStack(Blocks.AIR))) {
	//Do something
}

Am I really going to have to add the code to iterate over all slots in the inventory? or is there a much simpler way that I'm just not seeing here? (something along the lines of, less = more. Especially when it comes to readability).

EDIT: Probably worth noting, this is server-side code.

Edited January 14, 2018 by xorinzor
edited code block to Java instead of HTML

[xorinzor]

1 minute ago, diesieben07 said:

You will need to write a for loop and check for empty stacks. But most likely you don't want to actually find an empty stack, you want to check if there is room for some other stack, right?

 

Yea, all it needs to do is just check for a empty spot. Was hoping a iterator wouldn't be necessary, but I guess not haha.

[xorinzor]

5 minutes ago, diesieben07 said:

You don't need an iterator. There are several nice ways to do it using streams if you want to

haha oh boy, I'd rather not

This seems to work, so I'll just go with it.

 

public void someMethod() {

	checkFreeSlot: {
		for(int i=0; i < 36; i++) {
			if(player.inventory.getStackInSlot(i).equals(ItemStack.EMPTY)) {
				break checkFreeSlot;
			}
		}
		
		//Failed check	
		return;
	}

	//Check passed, do something.
}

 

[xorinzor]

10 minutes ago, diesieben07 said:

Don't use equals (or ==, they are equivalent here) for ItemStacks. To check if an ItemStack is empty you must use ItemStack::isEmpty.

It worked in testing, but I edited it  thanks.

[Draco18s]

1 hour ago, xorinzor said:

It worked in testing, but I edited it  thanks.

A stack of size 0 (but still with some other item) won't == ItemStack.EMPTY but it will still resolve .isEmpty() as true.

[KittenKoder]

One question that is related to this, should I make copies of ItemStack.EMPTY when using it to set an empty stack in methods that could potentially change it? 

[xorinzor]

21 minutes ago, KittenKoder said:

One question that is related to this, should I make copies of ItemStack.EMPTY when using it to set an empty stack in methods that could potentially change it? 

No that's not required, you can use ItemStack.EMPTY safely.

[American2050]

There is this method you can use also. Just check what int it returns and if it's on the range of inventory slots you want (Because I don't know if it would also return armor slots as empty slots)

player.inventory.getFirstEmptyStack()

 

Depending on what number you get, you will know that the player has a free slot.

[xorinzor]

1 minute ago, American2050 said:

There is this method you can use also. Just check what int it returns and if it's on the range of inventory slots you want (Because I don't know if it would also return armor slots as empty slots)

player.inventory.getFirstEmptyStack()

 

Depending on what number you get, you will know that the player has a free slot.

Awesome. That's exactly the kind of method I was looking for.