(1.18.2) force chunk reloading in block entity

[ElTotisPro50]

Why i need this: My block entity is a teleporter, you put an item with coordinates inside the gui and when you shift above the block it teleports you, the problem is that if both block entities are too far away one from another is crashes the game 

java.lang.NullPointerException: Cannot read field "itemHandler" because the return value of "net.minecraft.world.level.Level.getBlockEntity(net.minecraft.core.BlockPos)" is null

im pretty shure it needs the chunk loaded because it teleports me instantly and it doesnt have time to load the things of the block entity

 

My point is that in the tick method, im trying to force the chunk just like the player's spawnpoint does, but is throwing me this error:

Caused by: java.lang.NullPointerException: Cannot invoke "net.minecraft.server.MinecraftServer.getLevel(net.minecraft.resources.ResourceKey)" because the return value of "net.minecraft.world.level.Level.getServer()" is null

public static void tick(Level level, BlockPos pPos, BlockState pState, TeleportBlockEntity blockEntity) {
  	ChunkPos chunkPos = new ChunkPos(pPos);
        ResourceKey<Level> currentDimension = level.dimension();
        ServerLevel serverLevel = level.getServer().getLevel(currentDimension);
        ForgeChunkManager.forceChunk(serverLevel, Constants.MOD_ID, pPos, chunkPos.x,chunkPos.z,true,true);
}

 

[warjort]

What/where is that tick() method?

You are just showing some random code without any context.

 

From the error message it looks like it is getting called on the client, since Level.getServer() is returning null.

 

I would guess your other error (for which you don't even grace us with code) has the same problem.

Forcing chunk loading is not necessary to solve your problem.

Your problem is you can't reference chunks outside the render distance on the client. You shouldn't be doing this processing there.

[ElTotisPro50]

28 minutes ago, warjort said:

What/where is that tick() method?

You are just showing some random code without any context.

 

From the error message it looks like it is getting called on the client, since Level.getServer() is returning null.

 

I would guess your other error (for which you don't even grace us with code) has the same problem.

Forcing chunk loading is not necessary to solve your problem.

Your problem is you can't reference chunks outside the render distance on the client. You shouldn't be doing this processing there.

the chunk loading problem is solved but i realized that this is not necessary, actually is useless

// I had to add this if lol
if(!level.isClientSide) {
            ChunkPos chunkPos = new ChunkPos(pPos);
            ResourceKey<Level> currentDimension = level.dimension();
            ServerLevel serverLevel = (ServerLevel)level.getServer().getLevel(currentDimension);
            ForgeChunkManager.forceChunk(serverLevel, Constants.MOD_ID, pPos, chunkPos.x,chunkPos.z,true,true);
}

but actually as you said, forcing the chunks is not helping me, im back to problem 1

Caused by: java.lang.NullPointerException: Cannot read field "itemHandler" because the return value of "net.minecraft.world.level.Level.getBlockEntity(net.minecraft.core.BlockPos)" is null

what can i do

Edited September 4, 2022 by ElTotisPro50

[Potato5]

23 minutes ago, ElTotisPro50 said:

but actually as you said, forcing the chunks is not helping me, im back to problem 1

a little of topic, there is really, really no need to do it 20 times each second.

[ElTotisPro50]

Just now, Potato5 said:

a little of topic, there is really, really no need to do it 20 times each second.

yeah probably but im not forcing the chunks anymore

[warjort]

Quote

what can i do

You can start by making your question answerable. A one line NPE completely out of context is useless.

You don't even show the stacktrace - it needs more than that.

I wonder if you even know where in your code this error happens?

[ElTotisPro50]

5 minutes ago, warjort said:

I wonder if you even know where in your code this error happens?

If im correct, here (in the tick method): "ItemStack stack0 = ((TeleporterBlockEntity) level.getBlockEntity(pPos)).itemHandler.getStackInSlot(0);"

The weird thing is that minecraft only crashes sometimes and when it wants, for example if i have 2 teleports 500 blocks away from each and i use one of them minecraft crashes, or when i tp too far away, but that only crashes the game sometimes, is VERY WEIRD

 

BTW in the crash report the error is in line 219, this is line 219:

ItemStack stack0 = ((TeleporterBlockEntity) level.getBlockEntity(pPos)).itemHandler.getStackInSlot(0);

Crash report: https://pastebin.com/s2KqP6yX

Block entity Class:

public class TeleporterBlockEntity extends BlockEntity implements MenuProvider {

    private final ContainerData data;
	public final ItemStackHandler itemHandler = new ItemStackHandler(Constants.TELEPORTER_TOTALSLOTS) {
		@Override
		protected void onContentsChanged(int slot) {
            setChanged();
        };
};

    @Override
    public void setChanged() {
        super.setChanged();
    }

	private LazyOptional<IItemHandler> lazyItemHandler = LazyOptional.empty();

	public TeleporterBlockEntity(BlockPos pos, BlockState state) {
		super(ModBlockEntities.TELEPORTER_BLOCKENTITY.get(), pos, state);
	}

    @Override
	public AbstractContainerMenu createMenu(int id, Inventory inv, Player player) {
		return new TeleporterMenu(id, inv, this, this.data);
	}

	@Override
	public Component getDisplayName() {
		return new TextComponent("");
	}
	
	@Nonnull
    @Override
    public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @javax.annotation.Nullable Direction side) {
        if (cap == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY) {
            return lazyItemHandler.cast();
        }
        return super.getCapability(cap, side);
    }

    @Override
    public void onLoad() {
        super.onLoad();
        lazyItemHandler = LazyOptional.of(() -> itemHandler);
        ModMessages.sendToClients(new PacketSyncTeleporterPosToClient(posX,posY,posZ,dimName,worldPosition));
    }

    @Override
    public void invalidateCaps()  {
        super.invalidateCaps();
        lazyItemHandler.invalidate();
    }

    @Override
    protected void saveAdditional(@NotNull CompoundTag tag) {
        tag.put("inventory", itemHandler.serializeNBT());
        super.saveAdditional(tag);
    }
    @Override
    public void load(CompoundTag tag) {
        super.load(tag);
        itemHandler.deserializeNBT(tag.getCompound("inventory"));
    }

    public void drops() {
        SimpleContainer inventory = new SimpleContainer(itemHandler.getSlots());
        for (int i = 0; i < itemHandler.getSlots(); i++) {
            inventory.setItem(i, itemHandler.getStackInSlot(i));
        }
        Containers.dropContents(this.level, this.worldPosition, inventory);
    }

    public boolean hasCrystal() {
        return this.getItemFromSlot(0).getItem() == ModItems.TELEPORTCRYSTAL.get();
    }
    public void setItemToSlot(int slot, ItemStack stack) {
        stack.setCount(1);
        this.itemHandler.setStackInSlot(slot, stack);
    }
    public ItemStack getItemFromSlot(int slot) { return this.itemHandler.getStackInSlot(slot); }

    public static void tick(Level level, BlockPos pPos, BlockState pState, TeleporterBlockEntity blockEntity) {
        level.getEntitiesOfClass(Player.class, new AABB(pPos.getX(), pPos.getY(), pPos.getZ(), pPos.getX() + 1, pPos.getY() + 1, pPos.getZ() + 1)).forEach(entity -> {
            if(!(entity instanceof Player)) return;
            if(!entity.isShiftKeyDown() || !entity.isCrouching()) return;
            if(level.getBlockEntity(pPos) != null && level.getBlockEntity(pPos) instanceof TeleporterBlockEntity) {
                ItemStack stack = ((TeleporterBlockEntity) level.getBlockEntity(pPos)).itemHandler.getStackInSlot(0);
                CompoundTag tag = stack.getTag();
                if(tag == null) return;
                entity.playSound(SoundEvents.ENDERMAN_TELEPORT, 1, 1);
                if(!level.isClientSide) {
                    String dim = TotisPlayerUtils.getDimension(stack);
                    ResourceKey<Level> currentDim = level.dimension();
                    ServerLevel serverWorld = ((ServerLevel)level).getServer().getLevel(currentDim);
                    ServerPlayer player = (ServerPlayer)entity;
                    ResourceKey<Level> storedKey = ResourceKey.create(Registry.DIMENSION_REGISTRY, new ResourceLocation(dim));
                    ServerLevel storedWorld = ((ServerLevel)level).getServer().getLevel(storedKey);
                    if(serverWorld == storedWorld) {
                        player.teleportTo(tag.getInt("x")+0.5,tag.getInt("y")+1,tag.getInt("z")+0.5);
                    } else {
                        player.teleportTo(storedWorld, tag.getInt("x")+0.5,tag.getInt("y")+1,tag.getInt("z")+0.5, player.getRespawnAngle(), player.getRespawnAngle());
                    }
                }
                entity.playSound(SoundEvents.ENDERMAN_TELEPORT, 1, 1);
            }
        });
    }


    /*Synchronization to the client*/
    @Nullable
    @Override
    public Packet<ClientGamePacketListener> getUpdatePacket() {
        return ClientboundBlockEntityDataPacket.create(this);
    }
    @Override
    public CompoundTag getUpdateTag() {
        CompoundTag tag = saveWithoutMetadata();
        load(tag);
        return tag;
    }
    @Override
    public void onDataPacket(Connection net, ClientboundBlockEntityDataPacket pkt) {
        super.onDataPacket(net, pkt);
        load(pkt.getTag());
    }
    @Override
    public void handleUpdateTag(CompoundTag tag) {
        super.handleUpdateTag(tag);
    }
}

 

[warjort]

    public static void tick(Level level, BlockPos pPos, BlockState pState, TeleporterBlockEntity blockEntity) {

-- snip --

            if(level.getBlockEntity(pPos) != null && level.getBlockEntity(pPos) instanceof TeleporterBlockEntity) {
                ItemStack stack = ((TeleporterBlockEntity) level.getBlockEntity(pPos)).itemHandler.getStackInSlot(0);

Why are you doing all this extra work? You are told the TeleporterBlockEntity as a parameter to this method.

 

You still have this "broken" code, which I told you about on your previous thread but you obviously didn't fix it.

    @Override
    public CompoundTag getUpdateTag() {
        CompoundTag tag = saveWithoutMetadata();

        // Why are you loading during the save?
        load(tag);
        return tag;
    }
    @Override
    public void onDataPacket(Connection net, ClientboundBlockEntityDataPacket pkt) {
        super.onDataPacket(net, pkt); // This calls load()
        load(pkt.getTag()); // so this is duplicate work - in fact the whole onDataPacket() method is redundant, you can remove it and use the default implementation
    }

    // This is redundant too, overriding a method and just calling super is pointless
    @Override
    public void handleUpdateTag(CompoundTag tag) {
        super.handleUpdateTag(tag);
    }

 

When you've fixed your block entity load/save code and are sure it is working properly, either;

* create a new test world

* break all your BlockEntity blocks and replace them

that way you will know there aren't blocks lying around with broken nbt data from your previous buggy code

[ElTotisPro50]

7 minutes ago, warjort said:

    public static void tick(Level level, BlockPos pPos, BlockState pState, TeleporterBlockEntity blockEntity) {

-- snip --

            if(level.getBlockEntity(pPos) != null && level.getBlockEntity(pPos) instanceof TeleporterBlockEntity) {
                ItemStack stack = ((TeleporterBlockEntity) level.getBlockEntity(pPos)).itemHandler.getStackInSlot(0);

Why are you doing all this extra work? You are told the TeleporterBlockEntity as a parameter to this method.

 

You still have this "broken" code, which I told you about on your previous thread but you obviously didn't fix it.

    @Override
    public CompoundTag getUpdateTag() {
        CompoundTag tag = saveWithoutMetadata();

        // Why are you loading during the save?
        load(tag);
        return tag;
    }
    @Override
    public void onDataPacket(Connection net, ClientboundBlockEntityDataPacket pkt) {
        super.onDataPacket(net, pkt); // This calls load()
        load(pkt.getTag()); // so this is duplicate work - in fact the whole onDataPacket() method is redundant, you can remove it and use the default implementation
    }

    // This is redundant too, overriding a method and just calling super is pointless
    @Override
    public void handleUpdateTag(CompoundTag tag) {
        super.handleUpdateTag(tag);
    }

 

When you've fixed your block entity load/save code and are sure it is working properly, either;

* create a new test world

* break all your BlockEntity blocks and replace them

that way you will know there aren't blocks lying around with broken nbt data from your previous buggy code

Ok i created a new VOID world, put a teleporter without anything in it and teleported 500 blocks away, an that crashed my game with the exact same error, what the hell

/*Synchronization to the client*/
    @Nullable
    @Override
    public Packet<ClientGamePacketListener> getUpdatePacket() {
        return ClientboundBlockEntityDataPacket.create(this);
    }
    @Override
    public CompoundTag getUpdateTag() {
        return this.saveWithoutMetadata();
    }
    @Override
    public void onDataPacket(Connection net, ClientboundBlockEntityDataPacket pkt) {
        super.onDataPacket(net, pkt);
    }

 

[warjort]

    @Override
    public void onDataPacket(Connection net, ClientboundBlockEntityDataPacket pkt) {
        super.onDataPacket(net, pkt);
    }

This is still redundant.

 

Did you change the other code?

You know your level.getBlockEntity(BlockPos) code is running on both the client and server?

Doing it on the client is unsafe unless you check Level.isLoaded(BlockPos) first.

But as I said, you shouldn't need to call that method since you already have the block entity as a parameter.

Edited September 4, 2022 by warjort

[warjort]

Another solution would be to just not tick your block on the client.

Looking at your code, I don't see a reason why you need to do this?

Only ticking on the server would simplify your code and you wouldn't have to worry about sides.

See AbstractFurnaceBlock.createFurnaceTicker() for how to create a block entity ticker that only ticks on the server.