Just a simple question, if I use an Item how can I get that to reduce the data value for another item which is somewhere in the players inventory?

    public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer)
    {
    	if(par3EntityPlayer.inventory.hasItem(SaberMod.blasterBattery.shiftedIndex))
    	{
    		EntityBlast blast = new EntityBlast(par2World, par3EntityPlayer);
    		if (!par2World.isRemote)
        	{
    			par2World.spawnEntityInWorld(blast);
        	}
    	}
        return par1ItemStack;
    }

I have that to check if the play has the Item, but I need another check to see if the item (SaberMod.blasterBattery)'s data value is above 0. How would I do this? I can't see a way to do it from par3EntityPlayer.inventory

Fixed it, possibly, maybe not the best method but it seems like it would work;

public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer)
    {
	boolean hasBattery = par3EntityPlayer.inventory
			.hasItemStack(new ItemStack(SaberMod.blasterBattery, 1, 1))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 2))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 3))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 4))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 5))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 6))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 7))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, )
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 9))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 10))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 11))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 12))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 13))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 14))
			|| par3EntityPlayer.inventory.hasItemStack(new ItemStack(
					SaberMod.blasterBattery, 1, 15));
    	if(hasBattery)
    	{
    		EntityBlast blast = new EntityBlast(par2World, par3EntityPlayer);
    		if (!par2World.isRemote)
        	{
    			par2World.spawnEntityInWorld(blast);
        	}
    	}
        return par1ItemStack;
    }

After yet more improvement I've come up with this, and it's tested to be working, although it is quite a large method for something I deem quite simple.

public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer)
    {
	boolean hasBattery;

	List<ItemStack> batteries;
	List<Integer> slots;
	batteries = new ArrayList();
	slots = new ArrayList();

	for(int x = 0; x < par3EntityPlayer.inventory.getSizeInventory(); x++)
	{
		if(par3EntityPlayer.inventory.getStackInSlot(x) != null && par3EntityPlayer.inventory.getStackInSlot(x).getItem().shiftedIndex == SaberMod.blasterBattery.shiftedIndex)
		{
			batteries.add(par3EntityPlayer.inventory.getStackInSlot(x));
			slots.add(x);
		}
	}

	hasBattery = batteries.size()!= 0;

    	if(hasBattery)
    	{
    		for(int x = 0; x < batteries.size(); x++)
    		{
    			if(batteries.get(x).getItemDamage() != 0)
    			{
    				EntityBlast blast = new EntityBlast(par2World, par3EntityPlayer);
    				if (!par2World.isRemote)
    				{
    					par2World.spawnEntityInWorld(blast);
    				}
    				par3EntityPlayer.inventory.getStackInSlot(x).setItemDamage(par3EntityPlayer.inventory.getStackInSlot(x).getItemDamage() - 1);
    				break;
    			}
    		}
    		
    	}
        return par1ItemStack;
    }

 

If people can reduce the size of the method down I would be very grateful.

Okay that doesn't fully work either, does anyone have a solution?

Fixed it, here's a fix for future reference;

private ItemStack getInventoryFirstItemStack(EntityPlayer par2EntityPlayer)
    {
        for (int var1 = 0; var1 < par2EntityPlayer.inventory.mainInventory.length; ++var1)
        {
            if (par2EntityPlayer.inventory.mainInventory[var1] != null && par2EntityPlayer.inventory.mainInventory[var1].itemID == SaberMod.blasterBattery.shiftedIndex)
            {
            	if(par2EntityPlayer.inventory.getStackInSlot(var1).getItemDamage() > 0)
            	{
            		return par2EntityPlayer.inventory.getStackInSlot(var1);
            	}
            }
        }
        
        return null;
    }
    
    private void getSoundToPlay(EntityPlayer par2EntityPlayer)
    {
    	ItemStack stack = null;
        for (int var1 = 0; var1 < par2EntityPlayer.inventory.mainInventory.length; ++var1)
        {
            if (par2EntityPlayer.inventory.mainInventory[var1] != null && par2EntityPlayer.inventory.mainInventory[var1].itemID == SaberMod.blasterBattery.shiftedIndex)
            {
            		stack = par2EntityPlayer.inventory.getStackInSlot(var1);
            }
        }
        
        if(stack != null)
        {
        	if(stack.getItemDamage() > 0)
        	{
        		sendSoundPacket(4);
        	}
        	else
        	{
        		sendSoundPacket(3);
        	}
        }
    }

    /**
     * Called whenever this item is equipped and the right mouse button is pressed. Args: itemStack, world, entityPlayer
     */
    public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer)
    {
    	if(getInventoryFirstItemStack(par3EntityPlayer) != null)
    	{
    		EntityBlast blast = new EntityBlast(par2World, par3EntityPlayer);
    		if (!par2World.isRemote)
    		{
    			par2World.spawnEntityInWorld(blast);
    		}
    		getSoundToPlay(par3EntityPlayer);
    		getInventoryFirstItemStack(par3EntityPlayer).setItemDamage(getInventoryFirstItemStack(par3EntityPlayer).getItemDamage() - 1);
    	}
    	return par1ItemStack;
    }