I'm having two issues with the code below.
1. If I open an inventory without a backpack and equip it with a backpack in that inventory, no backpack slots will be added.
2. If I open an inventory with a backpack equipped and remove the backpack in that inventory, the backpack slot remains active.

What are the causes of these problems? Please help someone.

 

Backpack container: Although omitted, there is also a player inventory slot similar to a regular inventory container

public class BackpackPlayerContainer Container {
	private boolean addedBackpackSlot;

	public BackpackPlayerContainer(int id, PlayerInventory playerInventory, PacketBuffer extraData) {
		this(UMUContainers.BELONGING_INVENTORY.get(), id, playerInventory, playerInventory.player);
	}

	public BackpackPlayerContainer(ContainerType<?> type, int id, PlayerInventory playerInventory, PlayerEntity player) {
		super(type, id);

		this.addedBackpackSlot = false;

		
		if (EntityUtil.hasBackpack(player)) {
			for (int iV = 0; iV < 4; iV++) {
				for (int iU = 0; iU < 9; iU++) {
					this.addSlot(new BackpackSlot(player.getItemStackFromSlot(EquipmentSlotType.CHEST).getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY).orElse(new ItemStackHandler(36)), iU + iV * 9, 8 + iU * 18, 18 + iV * 18, player, iV + 1));
				}
			}
			this.addedBackpackSlot = true;
		}
	}

	@Override
	public ItemStack slotClick(int slotId, int dragType, ClickType clickTypeIn, PlayerEntity player) {
		if (!addedBackpackSlot && EntityUtil.hasBackpack(player)) {
			for (int iV = 0; iV < 4; iV++) {
				for (int iU = 0; iU < 9; iU++) {
					this.addSlot(new BackpackSlot(null, iU + (iV + 1) * 9, 8 + iU * 18, 18 + iV * 18, player, iV + 1));
				}
			}
         	addedBackpackSlot = true;
		}
		return super.slotClick(slotId, dragType, clickTypeIn, player);
	}
}

public class BackpackSlot extends SlotItemHandler {
	private final PlayerEntity player;
	private final int size;

	public BackpackSlot(IItemHandler inventoryIn, int index, int xPosition, int yPosition, PlayerEntity player, int size) {
		super(inventoryIn, index, xPosition, yPosition);
		this.player = player;
		this.size = size;
	}

	@Override
	public boolean isEnabled() {
		return EntityUtil.getBackpackSize(player) >= size;
	}
}

public class EntityUtil {
	public static boolean hasBackpack(LivingEntity entity) {
		if (entity.getItemStackFromSlot(EquipmentSlotType.CHEST).getItem() == ModItems.BACKPACK.get()) {
			return true;
		}

		return false;
	}

	public static int getBackpackSize(LivingEntity entity) {
		return 3;
	}
}

 

Edited June 5, 20214 yr by Zemelua

I believe this has to do with ho GUIs doesn't update like you'd think they'd do. A friend of mine mentioned this when I asked him a similar question. My best bet would be to look into that.

2 hours ago, Zemelua said:

1. If I open an inventory without a backpack and equip it with a backpack in that inventory, no backpack slots will be added.
2. If I open an inventory with a backpack equipped and remove the backpack in that inventory, the backpack slot remains active.

the container / inventory is not updated when you add / remove the backpack.
a container is created when it is opened and saved when it is closed.
between opening and closing the slot size is not updated.

the simplest solution would be to close the container and reopen it

Edited June 5, 20214 yr by Luis_ST

understood. So what is Slot # isEnabled? What is the difference between returning false with isEnabled with a slot added and not adding it in the first place?

Edited June 5, 20214 yr by Zemelua

Thank you. What is the best way to detect container changes, close the current container and reopen it?

2 minutes ago, Zemelua said:

What is the best way to detect container changes, close the current container and reopen it?

as far as I know, yes

Sorry. My English was bad. How do I detect changes in the container and reopen it?

27 minutes ago, Zemelua said:

Sorry. My English was bad. How do I detect changes in the container and reopen it?

use the Container#clicked method, check whether something has changed after clicking (item before clicked != item after clicked)

As far as I can see, there is no method called clicked in the Slot class. Do you mean slotClick ()? What do the arguments and return values of this method mean?

Also, how to close and reopen the container?

19 minutes ago, Zemelua said:

As far as I can see, there is no method called clicked in the Slot class. Do you mean slotClick ()? What do the arguments and return values of this method mean?

Also, how to close and reopen the container?

yes you probably don't use mojang mappings, which is why the methods have different names. (and update to a newer version there is no reason to use an "outdated" version)

did not use my suggestion but the one from @diesieben07, isEnabled the better solution for your project

18 minutes ago, diesieben07 said:

Why don't you just use isEnabled? No need to add/remove slots dynamically or reopen the container.

It goes back to the first problem.

 

5 hours ago, Zemelua said:

I'm having two issues with the code below.
1. If I open an inventory without a backpack and equip it with a backpack in that inventory, no backpack slots will be added.
2. If I open an inventory with a backpack equipped and remove the backpack in that inventory, the backpack slot remains active.

What are the causes of these problems? Please help someone.

 

Backpack container: Although omitted, there is also a player inventory slot similar to a regular inventory container

public class BackpackPlayerContainer Container {
	private boolean addedBackpackSlot;

	public BackpackPlayerContainer(int id, PlayerInventory playerInventory, PacketBuffer extraData) {
		this(UMUContainers.BELONGING_INVENTORY.get(), id, playerInventory, playerInventory.player);
	}

	public BackpackPlayerContainer(ContainerType<?> type, int id, PlayerInventory playerInventory, PlayerEntity player) {
		super(type, id);

		this.addedBackpackSlot = false;

		
		if (EntityUtil.hasBackpack(player)) {
			for (int iV = 0; iV < 4; iV++) {
				for (int iU = 0; iU < 9; iU++) {
					this.addSlot(new BackpackSlot(player.getItemStackFromSlot(EquipmentSlotType.CHEST).getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY).orElse(new ItemStackHandler(36)), iU + iV * 9, 8 + iU * 18, 18 + iV * 18, player, iV + 1));
				}
			}
			this.addedBackpackSlot = true;
		}
	}

	@Override
	public ItemStack slotClick(int slotId, int dragType, ClickType clickTypeIn, PlayerEntity player) {
		if (!addedBackpackSlot && EntityUtil.hasBackpack(player)) {
			for (int iV = 0; iV < 4; iV++) {
				for (int iU = 0; iU < 9; iU++) {
					this.addSlot(new BackpackSlot(null, iU + (iV + 1) * 9, 8 + iU * 18, 18 + iV * 18, player, iV + 1));
				}
			}
         	addedBackpackSlot = true;
		}
		return super.slotClick(slotId, dragType, clickTypeIn, player);
	}
}

public class BackpackSlot extends SlotItemHandler {
	private final PlayerEntity player;
	private final int size;

	public BackpackSlot(IItemHandler inventoryIn, int index, int xPosition, int yPosition, PlayerEntity player, int size) {
		super(inventoryIn, index, xPosition, yPosition);
		this.player = player;
		this.size = size;
	}

	@Override
	public boolean isEnabled() {
		return EntityUtil.getBackpackSize(player) >= size;
	}
}

public class EntityUtil {
	public static boolean hasBackpack(LivingEntity entity) {
		if (entity.getItemStackFromSlot(EquipmentSlotType.CHEST).getItem() == ModItems.BACKPACK.get()) {
			return true;
		}

		return false;
	}

	public static int getBackpackSize(LivingEntity entity) {
		return 3;
	}
}

 

I'm checking if I have a backpack in isEnabled but it's not working. Slots remain enabled / disabled with or without a backpack with the inventory open.

When I checked it now, there was no problem in the first one. If you equip the backpack later, it seems that slots will be added. However, if you remove the equipment from it again, the slot will remain active.