Minecraft 1.12.2 Tag System

Note: Block tags cannot distinguish between different metadata variants of the same block.

Features

• Create and manage tags for items, fluids, and blocks
• Automatic Ore Dictionary synchronization
• In-game command to check item/fluid tags
• High-performance lookups using fastutil collections
• Bidirectional queries: tags ↔ items/fluids/blocks

Usage

Creating Tags

Item Tags

TagBuilder.item("mymod:my_tag")
.add(new ItemStack(Items.APPLE))
.add(new ItemStack(Items.GOLDEN_APPLE));

TagBuilder.item("mymod:my_tag1", "mymod:my_tag2")
.add(new ItemStack(Items.APPLE))
.add(new ItemStack(Items.GOLDEN_APPLE));

Fluid Tags

TagBuilder.fluid("minecraft:lava")
.add(new FluidStack(FluidRegistry.LAVA, 1000));

TagBuilder.fluid("minecraft:lava", "lava")
.add(new FluidStack(FluidRegistry.LAVA, 1000));

Block Tags

TagBuilder.block("minecraft:stone_variants")
.add(Blocks.STONE)
.add(Blocks.ANDESITE);

TagBuilder.block("minecraft:stone_variants", "stone_variants")
.add(Blocks.STONE)
.add(Blocks.ANDESITE);

Querying Tags

In-Game Command

Use the /tag info command to view all tags
Use /tag hand while holding an item to see its tags:

• If holding a fluid container (like a bucket), shows fluid tags
• Otherwise, shows item tags

Code API

Get All Tags

// Get all tags for an item
Set<String> tags = TagHelper.tags(itemStack);

// Get all tags for a fluid
Set<String> tags = TagHelper.tags(fluidStack);

// Get all tags for a block
Set<String> tags = TagHelper.tags(block);

Check Specific Tag

// Check if an item has a specific tag
boolean hasTag = TagHelper.hasTag(itemStack, "minecraft:food");

// Check if a fluid has a specific tag
boolean hasTag = TagHelper.hasTag(fluidStack, "forge:lava");

Check Any Tags

// Check if an item has any of the specified tags
boolean hasAny = TagHelper.hasAnyTags(itemStack, "minecraft:food", "forge:tools");

// Check using a collection
List<String> tagList = Arrays.asList("minecraft:food", "forge:tools");
boolean hasAny = TagHelper.hasAnyTags(itemStack, tagList);

Get All Objects with a Tag

// Get all items with a specific tag
Set<ItemStack> items = TagHelper.getItemStacks("minecraft:food");

// Get all fluids with a specific tag
Set<FluidStack> fluids = TagHelper.getFluidStacks("forge:lava");

Tag Existence Check

// Check if a tag exists (any type)
boolean exists = TagHelper.tagNameExist("minecraft:food");

// Check if a tag exists for a specific type
boolean exists = TagHelper.tagNameExist("minecraft:food", TagType.ITEM);

Get All Tag Names

// Get all item tag names
Set<String> allItemTags = TagHelper.getAllTags(TagType.ITEM);

// Get all fluid tag names
Set<String> allFluidTags = TagHelper.getAllTags(TagType.FLUID);

Tag Naming Rules

• Can only contain: letters, nubmer, colon (:), underscore (_), slash (/)
• Cannot be null
• Examples: "minecraft:food", "forge:ore/iron", "Special_123"

Important Limitations

• Tag registration must be completed before FMLLoadCompleteEvent

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Credit

• JEI Integration [MIT]
• ForgeDevEnv [MIT]