Problems with ItemStack References

For my plugin, I need to schedule a task to check if an item is still in a player's inventory after several ticks, and I'm running into more trouble than expected.

Here's the method I created to check if the specified inventory contains the specified ItemStack:

Code:java

 public static boolean itemInInventory(ItemStack item, Inventory inv) {
for(int i = 0; i < inv.getSize(); i++) {
if(inv.getItem(i) == item) //If ItemStack in inventory references the same object as item...
return true;
}
 
return false;
}

And here's where I use it:

Code:java

 @EventHandler(priority=EventPriority.HIGHEST, ignoreCancelled=true)
public void onPlayerInteract(PlayerInteractEvent e) {
final Player player = e.getPlayer();
final ItemStack item = player.getItemInHand();
 
Bukkit.getScheduler().runTaskLater(plugin, new Runnable() {
@Override
public void run() {
if(!Util.itemInInventory(item, player.getInventory())) { //If item is no longer in player's inventory...
player.sendMessage("Item is no longer in your inventory!");
}
}
}, 5L);
}

The player right clicks, a reference to getItemInHand() is stored, and 5 ticks later, the itemInInventory method loops the player's inventory to see if it still contains a reference to the object specified. The problem is, itemInInventory always seems to return false, even when the player doesn't switch items. In testing, I also found that this code:

Code:java

player.getItemInHand() == player.getItemInHand();

returns false. Yet I can operate directly on the ItemStack returned by the method, like so:

Code:java

player.getItemInHand().setType(Material.IRON_INGOT);

and the code works... Could anyone explain this strange behavior to me?

 

ndvenckus1 Don't use ==
ItemStack.java Gives you the option of:
isSimilar()
equals()
getType().equals()

 

I'm not trying to figure out if the ItemStacks have the same data attached to them; I'm trying to figure out if their variables reference the same object, which is precisely what the == operator is for.

Can anyone explain this behavior?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Have you tried using DJSkepter 's method? That could at least isolate the problem

 

ndvenckus1

That the ItemStack is created when you request it from the player, and a reference to it is not maintained between calls to retrieve it from the inventory.

 

Ah, that makes sense. Thanks! I was under the impression that all ItemStacks on the server already existed in memory, and that when you made calls to retrieve them a reference was returned rather than a new object. With this being the case, I guess there's no way to get the inventory an ItemStack is located in, which is unfortunate.

 

ndvenckus1

I could certainly see where that idea comes from, and that's likely the way we'll do it in Trident. You could attach unique metadata to the item I believe, that would allow you to keep track of it.