I'm new to the forum, so just putting this out here, I have experience with Java (and other similar languages), however I'm very new to modding Minecraft, so much so I'm still largely following any tutorials I can find.

 

However I've hit a block, and I can't seem to figure this out. I'm just trying to get what the player is holding upon right-clicking a block, and then doing something if that item the player is holding matches a specific item.

 

Here's the method I'm working with as it is now:

 

@Override
    public boolean onBlockActivated(World worldIn, BlockPos pos, IBlockState state, EntityPlayer playerIn, EnumHand hand, EnumFacing facing, float hitX, float hitY, float hitZ) 
    { 
        if(!worldIn.isRemote)
        {
            TileEntity tileEntity = worldIn.getTileEntity(pos);
            if(tileEntity instanceof TileEntityJar) 
            {
                TileEntityJar jar = (TileEntityJar) tileEntity;
                
                if(playerIn.getActiveItemStack() != null)
                {
                    if(playerIn.getActiveItemStack() == new ItemStack(ModItems.cracker))
                    {
                        if(jar.addCracker())
                        {
                        int count = playerIn.getActiveItemStack().getCount();
                            playerIn.getActiveItemStack().setCount(count--);
                            return true;
                        }
                    }
                }
                jar.removeCracker();
            }
        }
        
        return true;
    }

 

Alternatively, the tutorial I'm following originally was using this:

 

@Override
    public boolean onBlockActivated(World worldIn, BlockPos pos, IBlockState state, EntityPlayer playerIn, EnumHand hand, EnumFacing facing, float hitX, float hitY, float hitZ) 
    { 
        if(!worldIn.isRemote)
        {
            TileEntity tileEntity = worldIn.getTileEntity(pos);
            if(tileEntity instanceof TileEntityJar) 
            {
                TileEntityJar jar = (TileEntityJar) tileEntity;
                
                if(heldItem != null)
                {
                    if(heldItem.getItem() == ModItems.cracker)
                    {
                        if(jar.addCracker())
                        {
                            heldItem.stackSize--;
                            return true;
                        }
                    }
                }
                jar.removeCracker();
            }
        }
        return true;
    }

 

 

the "heldItem" keyword was something this person put in and it just worked, but for me I only get an error and I can't find any possible thing I did wrong. I don't know if there's an import I'm missing or what. Some help would really be appreciated.

 

Edited May 17, 20178 yr by JakeZ1990

7 minutes ago, JakeZ1990 said:

if(playerIn.getActiveItemStack() == new ItemStack(ModItems.cracker))

You are comparing by reference, and not by content. Additionally you are comparing an object by reference with a newly created object. That comparason will obviously always fail. 

The original tutorial you've linked compares an item from the itemstack with an item instance stored somewhere else. Items are singletons, meaning that that comparason can succeed. 

So that part turns into

if(playerIn.getActiveItemStack().getItem() == ModItems.cracker)

You might additionally want to check the damage value, if needed. It can be obtained with ItemStack::getMetadata() or ItemStack::getItemDamage()

you cannot compare an existing ItemStack to the one you just created like that... you're asking if it's the very same object. it is not.

ItemStack has GetItem method. compare results of those (items are singletons, you can do that). then do something with entire stack or just one item and reduce the count.

The heldItem parameter was removed from the method in 1.11, since you can get it from the EntityPlayer using EntityLivingBase#getHeldItem (EntityPlayer extends EntityLivingBase).

 

EntityLivingBase#getActiveItemStack only returns a non-empty ItemStack when the entity is actively using an item (e.g. blocking with a shield, drawing a bow).

 

ItemStacks can no longer be null in 1.11+, the default value is now the empty ItemStack. Use ItemStack#isEmpty to check if an ItemStack is empty. The ItemStack.EMPTY field contains an ItemStack that's always empty.

25 minutes ago, V0idWa1k3r said:

You are comparing by reference, and not by content. Additionally you are comparing an object by reference with a newly created object. That comparason will obviously always fail. 

The original tutorial you've linked compares an item from the itemstack with an item instance stored somewhere else. Items are singletons, meaning that that comparason can succeed. 

So that part turns into

if(playerIn.getActiveItemStack().getItem() == ModItems.cracker)

You might additionally want to check the damage value, if needed. It can be obtained with ItemStack::getMetadata() or ItemStack::getItemDamage()

I attempted your modification, however it still fails the check.

 

 

24 minutes ago, Choonster said:

The heldItem parameter was removed from the method in 1.11, since you can get it from the EntityPlayer using EntityLivingBase#getHeldItem (EntityPlayer extends EntityLivingBase).

 

EntityLivingBase#getActiveItemStack only returns a non-empty ItemStack when the entity is actively using an item (e.g. blocking with a shield, drawing a bow).

 

ItemStacks can no longer be null in 1.11+, the default value is now the empty ItemStack. Use ItemStack#isEmpty to check if an ItemStack is empty. The ItemStack.EMPTY field contains an ItemStack that's always empty.

 

I'm not quite sure how I'd utilize your information? As I said, I'm strictly following tutorials at this point, I'm not very familiar with MDKs code base at all.

Choonster's information explains why the check failed - player#getActiveItemStack only returns a stack if it's currently in use (like charging a bow). When a player right-clicks on your block, the item they're holding isn't in use, so player#getActiveItemStack will always be empty. If you want to know the stack they have in their hand (regardless of whether it's in use), you can use player#getHeldItem using the EnumHand parameter passed to the method (the player's current active hand).

7 hours ago, Jay Avery said:

Choonster's information explains why the check failed - player#getActiveItemStack only returns a stack if it's currently in use (like charging a bow). When a player right-clicks on your block, the item they're holding isn't in use, so player#getActiveItemStack will always be empty. If you want to know the stack they have in their hand (regardless of whether it's in use), you can use player#getHeldItem using the EnumHand parameter passed to the method (the player's current active hand).

Okay, I get what you're saying, so I found a method I believe will do what I want:

if(playerIn.getHeldItem(hand) == (ModItems.cracker))

However, my issue now is that it's telling me Item and ItemStack are incompatible operand types.

That's because Item and ItemStack are different types. getHeldItem returns an ItemStack (not an Item). Use stack#getItem, like in V0idWa1k3r's first post.

Edited May 17, 20178 yr by Jay Avery

25 minutes ago, Jay Avery said:

That's because Item and ItemStack are different types. getHeldItem returns an ItemStack (not an Item). Use stack#getItem, like in V0idWa1k3r's first post.

Ohh! Yea, I knew they were different types. I was just being a dummy and forgot to check getHeldItem() for more sub-methods. So It's actually succeeding the If statement now, and placing crackers in the jar, which I can then take out, however, there is one last issue in my snippet.

int count = playerIn.getHeldItem(hand).getCount();
                            playerIn.getHeldItem(hand).setCount(count--);
                            return true;

For some reason, this section here is not decreasing the player's stack by 1.

 

[EDIT] Actually just fixed it by doing this instead:

playerIn.getHeldItem(hand).setCount(playerIn.getHeldItem(hand).getCount() - 1);
                            return true;

 

Although, if you don't mind, do you know why using the int like I was wasn't working?

Edited May 17, 20178 yr by JakeZ1990

You were using the postfix decrement operator (count--), which is applied after the rest of the expression is evaluated. So the code was saying "set this stack size to count, and then reduce the local count variable by 1". If you used the prefix operator (--count) it would reduce count by one before using it in the method. But there's also a simpler way of doing this in one line with no local variable - the method ItemStack#shrink will reduce the stack size of the stack by the number you give it.

2 hours ago, Jay Avery said:

You were using the postfix decrement operator (count--), which is applied after the rest of the expression is evaluated. So the code was saying "set this stack size to count, and then reduce the local count variable by 1". If you used the prefix operator (--count) it would reduce count by one before using it in the method. But there's also a simpler way of doing this in one line with no local variable - the method ItemStack#shrink will reduce the stack size of the stack by the number you give it.

Okay cool! Thanks a ton for the tip. Sorry for the late response, had to go to work. I'll be sure to mess around with that when I get the chance. I'm very happy you guys were all so kind to help me out so quickly. I'll definitely be coming here again if I hit another roadblock

(Hopefully with decreasing frequency, I've been pretty proud of my learning capabilities in the past, lol)