Solved Menu get null slots.

Slots are never null anymore. Check for Material.AIR instead

 

What version are you using?

 

Yeah, that's super old

Your slots could be null or air, so you have to check both.

Also, in your code change 22 to slot.

 

Are you sure there are items in those slots? Maybe you have the slot numbers wrong.

http://wiki.vg/Inventory

 

Code (Java):

for (int slot = 20; slot <= 24; slot++) {
    if (inv.getItem(slot) == null || inv.getItem(slot).getType() == Material.AIR ) {
        inv.setItem(slot, item);
    }
}

This will put the item where there are no item

 

Can you show us the full code with full error message?

In my opinion the inventory is null.
null.getItem() -> I think this is why you get the error.

Show me how do you get/create inventory?

 

If inventory is null it's normal that it throw nullpointer. You have to check for null inventory and after check with only one if for the slots that you want to check

 

In your code you set the item every time ONE of the slots is null not if all of them are

EDIT: you could use:

Code (Text):

boolean b = true;
for (int slot = 20; slot <= 24; slot++) {
    if (inv.getItem(slot) != null && inv.getItem(slot).getType() != Material.AIR ) {
        b=false;
    }
}
if(b) {
    setItem(22,item);
}