[1.16.x] Custom block as a shop

[Retsal]

Hey, I'm new to minecraft modding, but I know java programming.

I am trying to create a custom block that can exchange items when you right click on it, and it gives you the item only if you have enough coins. You will find a picture of the scene attached to this post.

 

Problem: When you right click on the block, it gives you the item if you have enough coins. But if you disconnect and then reconnect to the world, something undoes the changes made by the transaction.

 

I think it happens because I am writing the code on the client side and not updating the information on the server side. But I have no idea how I should do it properly.

 

Code of the Block class:

public class BlockShop extends Block {
	
	public BlockShop() {
		super(AbstractBlock.Properties
				.create(Material.BARRIER)
				.hardnessAndResistance(-1)
		);
	}
	
	@Override
	public ActionResultType onBlockActivated(
			BlockState state, World world, BlockPos pos,
			PlayerEntity player, Hand hand, BlockRayTraceResult hit) {
		BlockState signState = world.getBlockState(pos.down());
		if (signState != null) {
			Block blockSign = world.getBlockState(pos.down()).getBlock();
			if (blockSign.getRegistryName().toString().equals("minecraft:oak_sign")) {
				Item item = blockSign.getBlock().asItem();
				TileEntity te = world.getTileEntity(pos.down());
				String sellId = "";
				int price = -1;
				int quantity = -1;
				if (world.isRemote && te instanceof SignTileEntity) {
					SignTileEntity signTe = (SignTileEntity)te;
					String description = signTe.getText(0).getString();
					sellId = signTe.getText(1).getString();
					String stringPrice = signTe.getText(2).getString();
					String stringQuantity = signTe.getText(3).getString();
					try {
						price = Integer.parseInt(stringPrice);
						quantity = Integer.parseInt(stringQuantity);
						buyItem(player, world, sellId, price, quantity);
					}
					catch (Exception e) {
						
					}
				}
			}
		}
			
		return ActionResultType.CONSUME;
	}
	
	private void buyItem(PlayerEntity player, World world, String itemId, int price, int quantity) {
		PlayerInventory inv = player.inventory;
		ItemStack creditStack = InitItems.CREDIT_ITEM.get().getDefaultInstance();
		ItemStack itemStack = null;
		if (itemId.contains("blueberry"))
			itemStack = InitItems.FRESISUIS_BLUEBERRY.get().getDefaultInstance();
		else if (itemId.contains("lemon"))
			itemStack = InitItems.FRESISUIS_LEMON.get().getDefaultInstance();
		else if (itemId.contains("lime"))
			itemStack = InitItems.FRESISUIS_LIME.get().getDefaultInstance();
		else if (itemId.contains("orange"))
			itemStack = InitItems.FRESISUIS_ORANGE.get().getDefaultInstance();
		else if (itemId.contains("strawberry"))
			itemStack = InitItems.FRESISUIS_STRAWBERRY.get().getDefaultInstance();
		else if (itemId.contains("suppository"))
			itemStack = InitItems.GLOWING_SUPPOSITORY.get().getDefaultInstance();
		
		if (itemStack != null && inv.count(creditStack.getItem()) >= price) {
			inv.decrStackSize(inv.getSlotFor(creditStack), price);
			itemStack.setCount(quantity);
			inv.add(inv.getFirstEmptyStack(), itemStack);
		}
	}
}

 

Any help is appreciated

Thank you so much and sorry for my level of english.

Edited March 3, 2021 by Retsal
Rewrote some sentences.

[Draco18s]

2 hours ago, Retsal said:

if (world.isRemote

Yes. Let's let the client that is a cheating bastard be the only side that knows anything happened.

 

Additionally:

2 hours ago, Retsal said:

catch (Exception e) {

This is not how you catch exceptions.

2 hours ago, Retsal said:

if (blockSign.getRegistryName().toString().equals("minecraft:oak_sign")) {

Ah yes, the only type of sign that matters is the one that has the stringy name minecraft:oak_sign. Why not use the constants in the Blocks class?

if(blockSign == Blocks.SIGN)

2 hours ago, Retsal said:

if (world.isRemote && te instanceof SignTileEntity) {

Or fuck it, skip straight to here. If there isn't a sign below your shop, there won't be a SignTileEntity below your shop.

2 hours ago, Retsal said:

ItemStack itemStack = null;

ItemStacks should never be null. Use ItemStack.EMPTY and use .isEmpty()

2 hours ago, Retsal said:

creditStack.getItem()) >= price

What if the player has two stacks of credits in their inventory, each smaller than the price, but totaled is greater than the price? i.e. what if you set the buy price to 100?

2 hours ago, Retsal said:

itemStack.setCount(quantity);

What happens if the quantity is greater than the maximum stack size for this item?

[Retsal]

Thanks for your quick response @Draco18s. I have laughed a lot with some of your answers, especially with the webpage where they explained Yoda's if 😂

4 hours ago, Draco18s said:

Yes. Let's let the client that is a cheating bastard be the only side that knows anything happened.

 

Updated code:

public class BlockShop extends Block {
	
	public BlockShop() {
		super(AbstractBlock.Properties
				.create(Material.BARRIER)
				.hardnessAndResistance(-1)
		);
	}
	
	@Override
	public ActionResultType onBlockActivated(
			BlockState state, World world, BlockPos pos,
			PlayerEntity player, Hand hand, BlockRayTraceResult hit) {
		BlockState signState = world.getBlockState(pos.down());
		if (signState != null) {
			Block blockSign = world.getBlockState(pos.down()).getBlock();
			if (blockSign == Blocks.OAK_SIGN) {
				Item item = blockSign.getBlock().asItem();
				TileEntity te = world.getTileEntity(pos.down());
				String sellId = "";
				int price = -1;
				int quantity = -1;
				if (te instanceof SignTileEntity) {
					SignTileEntity signTe = (SignTileEntity)te;
					String description = signTe.getText(0).getString();
					sellId = signTe.getText(1).getString();
					String stringPrice = signTe.getText(2).getString();
					String stringQuantity = signTe.getText(3).getString();
					try {
						price = Integer.parseInt(stringPrice);
						quantity = Integer.parseInt(stringQuantity);
						buyItem(player, world, sellId, price, quantity);
					}
					catch (NumberFormatException e) {
						e.printStackTrace(System.err);
					}
				}
			}
		}
			
		return ActionResultType.CONSUME;
	}
	
	private void buyItem(PlayerEntity player, World world, String itemId, int price, int quantity) {
		PlayerInventory inv = player.inventory;
		ItemStack creditStack = InitItems.CREDIT_ITEM.get().getDefaultInstance();
		ItemStack itemStack = ItemStack.EMPTY;
		if (itemId.contains("blueberry"))
			itemStack = InitItems.FRESISUIS_BLUEBERRY.get().getDefaultInstance();
		else if (itemId.contains("lemon"))
			itemStack = InitItems.FRESISUIS_LEMON.get().getDefaultInstance();
		else if (itemId.contains("lime"))
			itemStack = InitItems.FRESISUIS_LIME.get().getDefaultInstance();
		else if (itemId.contains("orange"))
			itemStack = InitItems.FRESISUIS_ORANGE.get().getDefaultInstance();
		else if (itemId.contains("strawberry"))
			itemStack = InitItems.FRESISUIS_STRAWBERRY.get().getDefaultInstance();
		else if (itemId.contains("suppository"))
			itemStack = InitItems.GLOWING_SUPPOSITORY.get().getDefaultInstance();
		
		if (!itemStack.isEmpty() && inv.count(creditStack.getItem()) >= price) {
			inv.decrStackSize(inv.getSlotFor(creditStack), price);
			itemStack.setCount(quantity);
			inv.add(inv.getFirstEmptyStack(), itemStack);
		}
	}
}

 

4 hours ago, Draco18s said:

if(blockSign == Blocks.SIGN)

I didn't find Blocks.SIGN in net.minecraft.block.Blocks nor net.minecraft.forge.common.Tags so for the moment I will check block.Blocks.OAK_SIGN.

 

4 hours ago, Draco18s said:

What if the player has two stacks of credits in their inventory, each smaller than the price, but totaled is greater than the price? i.e. what if you set the buy price to 100?

What happens if the quantity is greater than the maximum stack size for this item?

Well, the desired behavior would be that if the price exceeds the maximum stack size, then the mod will be able to count the total coins. But I think that (for the moment) it would not be a problem, because I can iterate the slots and calculate the total count. In the same way, I can calculate if I can deposit the desired amount of items sold in the player's inventory.

 

I had to delegate to the client because I don't know how to capture the text of the sign with the server. If I remove the condition of being a client when capturing the text if I run the mod in Singleplayer it works fine, but if I run it on a server it causes a crash with the following exception, and I don't know how to fix it:

java.lang.NoSuchMethodError: net.minecraft.tileentity.SignTileEntity.func_212366_a(I)Lnet/minecraft/util/text/ITextComponent;
	at retsal.rsmakeitharder.common.block.BlockShop.func_225533_a_(BlockShop.java:45) ~[rsmakeitharder:0.2] {re:classloading}
	at net.minecraft.block.AbstractBlock$AbstractBlockState.func_227031_a_(AbstractBlock.java:638) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.server.management.PlayerInteractionManager.func_219441_a(PlayerInteractionManager.java:338) ~[?:?] {re:classloading}
	at net.minecraft.network.play.ServerPlayNetHandler.func_184337_a(ServerPlayNetHandler.java:958) ~[?:?] {re:classloading}
	at net.minecraft.network.play.client.CPlayerTryUseItemOnBlockPacket.func_148833_a(SourceFile:36) ~[?:?] {re:classloading}
	at net.minecraft.network.play.client.CPlayerTryUseItemOnBlockPacket.func_148833_a(SourceFile:10) ~[?:?] {re:classloading}
	at net.minecraft.network.PacketThreadUtil.func_225383_a(SourceFile:21) ~[?:?] {re:classloading}
	at net.minecraft.util.concurrent.TickDelayedTask.run(SourceFile:18) ~[?:?] {re:classloading}
	at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213166_h(SourceFile:144) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.util.concurrent.RecursiveEventLoop.func_213166_h(SourceFile:23) ~[?:?] {re:classloading}

 

Thank you so much for your help

[Draco18s]

You will need to look at the SignTileEntity class to determine what functions are available server-side that lets you access the data you want.

24 minutes ago, Retsal said:

I didn't find Blocks.SIGN in net.minecraft.block.Blocks nor net.minecraft.forge.common.Tags so for the moment I will check block.Blocks.OAK_SIGN.

Ok, yes, it's OAK_SIGN. But you can skip that check entirely and just grab the TE at the location. If it is null or not a sign TE, do nothing.

[Retsal]

Finally it is working. Thank you so much for the hints and for pointing me to the right direction @Draco18s.

I'm going to share a functional version. Although it is not finished, I think it can help someone who has the same issue.

public class BlockShop extends Block {
	
	public BlockShop() {
		super(AbstractBlock.Properties
				.create(Material.BARRIER)
				.hardnessAndResistance(-1)
		);
	}
	
	@Override
	public ActionResultType onBlockActivated(
			BlockState state, World world, BlockPos pos,
			PlayerEntity player, Hand hand, BlockRayTraceResult hit) {
		if (!world.isRemote) { // Server side
			BlockState signState = world.getBlockState(pos.down());
			if (signState != null) {
				Block blockSign = signState.getBlock();
				if (blockSign == Blocks.OAK_SIGN) {
					Item item = blockSign.getBlock().asItem();
					TileEntity te = world.getTileEntity(pos.down());
					SignTileEntity signTe = (SignTileEntity)te;
					CompoundNBT nbt = signTe.getUpdateTag();
					String sellId = "";
					int price = -1;
					int quantity = -1;
					try {
						sellId = ITextComponent.Serializer
								.getComponentFromJson(nbt.getString("Text2"))
								.getString();
						price = Integer.parseInt(ITextComponent.Serializer
								.getComponentFromJson(nbt.getString("Text3"))
								.getString()
								);
						quantity = Integer.parseInt(ITextComponent.Serializer
								.getComponentFromJson(nbt.getString("Text4"))
								.getString()
								);
						
					} catch (NumberFormatException e) {
						e.printStackTrace(System.err);
					}
					buyItem(player, world, sellId, price, quantity);
				}
			}
		}
		return ActionResultType.CONSUME;
	}
	
	private void buyItem(PlayerEntity player, World world, String itemId, int price, int quantity) {
		PlayerInventory inv = player.inventory;
		ItemStack creditStack = InitItems.CREDIT_ITEM.get().getDefaultInstance();
		ItemStack itemStack = ItemStack.EMPTY;
		if (itemId.contains("blueberry"))
			itemStack = InitItems.FRESISUIS_BLUEBERRY.get().getDefaultInstance();
		else if (itemId.contains("lemon"))
			itemStack = InitItems.FRESISUIS_LEMON.get().getDefaultInstance();
		else if (itemId.contains("lime"))
			itemStack = InitItems.FRESISUIS_LIME.get().getDefaultInstance();
		else if (itemId.contains("orange"))
			itemStack = InitItems.FRESISUIS_ORANGE.get().getDefaultInstance();
		else if (itemId.contains("strawberry"))
			itemStack = InitItems.FRESISUIS_STRAWBERRY.get().getDefaultInstance();
		else if (itemId.contains("suppository"))
			itemStack = InitItems.GLOWING_SUPPOSITORY.get().getDefaultInstance();
		
		// TODO: check if space is available before removing coins
		int initialCoins = inv.count(creditStack.getItem());
		if (!itemStack.isEmpty() && initialCoins >= price) {
			int freeSlotIndex = inv.getFirstEmptyStack(); // TODO: replace by <append to firstItemStack>
			itemStack.setCount(quantity);
			int toPay = price;
			while (toPay > 0) {
				int coinSlotIndex = inv.findSlotMatchingUnusedItem(creditStack);
				ItemStack coinSlot = inv.getStackInSlot(coinSlotIndex);
				int amount = Math.min(coinSlot.getCount(), toPay);
				coinSlot.setCount(coinSlot.getCount() - amount);
				player.replaceItemInInventory(coinSlotIndex, coinSlot);
				toPay -= amount;
			}
			player.replaceItemInInventory(freeSlotIndex, itemStack);
		}
	}
}

 

[Draco18s]

2 hours ago, Retsal said:

					} catch (NumberFormatException e) {
						e.printStackTrace(System.err);
					}
					buyItem(player, world, sellId, price, quantity);

So, if your parses throw a NumberFormatException.... what values will price and quantity contain when buyItem is called?

2 hours ago, Retsal said:

if (blockSign == Blocks.OAK_SIGN) {

You still don't actually need this check.

2 hours ago, Retsal said:

CompoundNBT nbt = signTe.getUpdateTag();
nbt.getString("Text2")

You don't need to do this...

signTe.signText

is a public ITextComponentString[]...

Edited March 4, 2021 by Draco18s

[Retsal]

When i wrote the above post it was too late and i just made a working version. So I am going to upload a cleaner version and I hope it helps someone.

 

11 hours ago, Draco18s said:

So, if your parses throw a NumberFormatException.... what values will price and quantity contain when buyItem is called?

I don't know when I put it out of the try scope, but it should definitely be inside.

 

11 hours ago, Draco18s said:

signTe.signText

is a public ITextComponentString[]...

I think it is not a public property. Maybe I am wrong, but in 1.16.5-36.0.42 it is coded as private.

 

Below I upload a cleaner version:

public class BlockShop extends Block {
	
	public BlockShop() {
		super(AbstractBlock.Properties
				.create(Material.BARRIER)
				.hardnessAndResistance(-1)
		);
	}
	
	@Override
	public ActionResultType onBlockActivated(
			BlockState state, World world, BlockPos pos,
			PlayerEntity player, Hand hand, BlockRayTraceResult hit) {
		if (!world.isRemote) { // Just server side needed
			TileEntity te = world.getTileEntity(pos.down());
			if (te instanceof SignTileEntity) {
				SignTileEntity signTe = (SignTileEntity)te;
				try {
					String[] signText = getSignText(signTe);
					String sellId = signText[1];
					int price = Integer.parseInt(signText[2]);
					int quantity = Integer.parseInt(signText[3]);
					buyItem(player, world, sellId, price, quantity);
					
				} catch (NumberFormatException | NullPointerException e) {
					e.printStackTrace(System.err);
				}
			}
		}
		return ActionResultType.CONSUME;
	}
	
	private String[] getSignText(SignTileEntity signTe) {
		CompoundNBT nbt = signTe.getUpdateTag();
		String[] text = new String[4];
		for (int i = 0; i < 4; i++)
			text[i] = ITextComponent.Serializer
				.getComponentFromJson(nbt.getString("Text" + (i + 1)))
				.getString();
		return text;
	}
	
	private void buyItem(PlayerEntity player, World world, String itemId, int price, int quantity) {
		PlayerInventory inv = player.inventory;
		ItemStack creditStack = InitItems.CREDIT_ITEM.get().getDefaultInstance();
		ItemStack itemStack = getItemStackByName(itemId);
		
		int initialCoins = inv.count(creditStack.getItem());
		if (!itemStack.isEmpty() 
				&& initialCoins >= price
				&& isAvailableSpaceForItem(quantity, player, itemStack)
			) {
			doPayment(price, player, creditStack);
			giveItemsToPlayer(quantity, player, itemStack);
		}
	}
	
	private void giveItemsToPlayer(int quantity, PlayerEntity player, ItemStack itemStack) {
		itemStack.setCount(quantity);
		player.addItemStackToInventory(itemStack);
	}
	
	private boolean isAvailableSpaceForItem(int quantity, PlayerEntity player, ItemStack itemStack) {
		PlayerInventory inv = player.inventory;
		int leftInInventory = inv.count(itemStack.getItem()) % itemStack.getMaxStackSize();
		int freeSlotsNeeded = (int)Math.ceil((quantity - leftInInventory) / (double)itemStack.getMaxStackSize());
		if (freeSlotsNeeded == 0)
			return true;
		for (ItemStack is : inv.mainInventory)
			if (is.isEmpty() && --freeSlotsNeeded == 0)
				return true;
		return false;
	}
	
	private void doPayment(int price, PlayerEntity player, ItemStack coinType) {
		PlayerInventory inv = player.inventory;
		int toPay = price;
		while (toPay > 0) {
			int coinSlotIndex = inv.findSlotMatchingUnusedItem(coinType);
			ItemStack coinSlot = inv.getStackInSlot(coinSlotIndex);
			int amount = Math.min(coinSlot.getCount(), toPay);
			coinSlot.setCount(coinSlot.getCount() - amount);
			player.replaceItemInInventory(coinSlotIndex, coinSlot);
			toPay -= amount;
		}
	}
	
	private ItemStack getItemStackByName(String name) {
		ItemStack itemStack = ItemStack.EMPTY;
		if (name.contains("blueberry"))
			itemStack = InitItems.FRESISUIS_BLUEBERRY.get().getDefaultInstance();
		else if (name.contains("lemon"))
			itemStack = InitItems.FRESISUIS_LEMON.get().getDefaultInstance();
		else if (name.contains("lime"))
			itemStack = InitItems.FRESISUIS_LIME.get().getDefaultInstance();
		else if (name.contains("orange"))
			itemStack = InitItems.FRESISUIS_ORANGE.get().getDefaultInstance();
		else if (name.contains("strawberry"))
			itemStack = InitItems.FRESISUIS_STRAWBERRY.get().getDefaultInstance();
		else if (name.contains("suppository"))
			itemStack = InitItems.GLOWING_SUPPOSITORY.get().getDefaultInstance();
		return itemStack;
	}
}

 

Thank you for your help

 

[Draco18s]

29 minutes ago, Retsal said:

Maybe I am wrong, but in 1.16.5-36.0.42 it is coded as private.

I didn't have that version downloaded so looked at the most current version I had.