Detecting an item and performing actions on it in a player's inventory

[Glorfindel22]

Like the title says I am trying to detect if the player has a certain item in their inventory, and if they do perform a few actions on it. I have been struggling to find a way to do that, at first I figured I would use the "haveItemStack" method, however while that would tell me they have it doesn't return the itemstack which I would need to perform the actions on. So now I have been thinking about doing a for loop that would look through every item in the inventory using the getStackInSlot method. But I can't seem to figure out what values i can be and how that number would relate to the rest of the inventory. Anyone know? Or better yet does anyone know of another easier way to do what I am trying to?

[GamingTom]

I don't know how you would detect if an item is in the inventory, but I have been detecting when an item is picked up for my mod. For example, when an item is picked up, a specified action takes place.

 

public class PickupHandler implements IPickupNotifier {
@Override
public void notifyPickup(EntityItem item, EntityPlayer player) {

                if (item.getEntityItem().itemID == Items.yourItem.itemID){
                      <perform an action>
                }
        }
}

 

Hope this helps!

[GotoLink]

Depends on when you want the actions to be done.

 

But yes, straight forward approach is to run a for loop on the player inventory slots.

[crackedEgg]

Here is how I do this in my parachute mod.

public static ItemStack inventoryContainsAAD(InventoryPlayer inventory) {
ItemStack itemstack = null;
for (ItemStack s : inventory.mainInventory) {
	if (s != null && s.getItem() instanceof ItemAutoActivateDevice) {
		itemstack = s;
		break;
	}
}
return itemstack;
}

 

you can view the code at https://github.com/m1k3s/parachute

[coolAlias]

How about the 'onUpdate' method from Item? It is called automatically for every ItemStack containing your Item each tick, so long as you override this method in your Item class. Maps use it to update while being held, but it's called so long as the item is in your inventory, not necessarily held.

 

These are the parameters:

public void onUpdate(ItemStack itemstack, World world, Entity entity, int par4, boolean isCurrentItem)

Sorry I'm not sure what 'par4' is, I think ticks in use but I may be wrong.

[chimera27]

Just make a commontickhandler that implements ITickHandler and use

if(player.inventory.hasItem(Main.itemwhatever.itemID){
Do Stuff.
}

(Just google how to make a common tick handler if you're unsure)

Also for reference here's how I check if the player has a power beam and an upgrade in their inventory, and if so consumes them and adds a power beam that can switch to the ice beam:

 

if (player.inventory.hasItem(Main.ItemIceUpgrade.itemID) && player.inventory.hasItem(Main.ItemPowerBeam.itemID)) {
		player.inventory.consumeInventoryItem(Main.ItemIceUpgrade.itemID);
		player.inventory.consumeInventoryItem(Main.ItemPowerBeam.itemID);
		player.inventory.addItemStackToInventory(ItemPowerBeamStackI);


	}

 

Hope it helps!

[Mew]

A slightly better, and less resource/time consuming way to do this would be to implement to of the earlier said ways. You would first do a check to see if the player has the item in their inventory, THEN run the for loop to get what slot it is in, and from there, get the itemstack.

If the player doesn't have the item... Just do nothing.

[Draco18s]

You would first do a check to see if the player has the item in their inventory, THEN run the for loop

 

How can you detect that the item exists in the array without looking at the array?