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Group System

What You Will Learn​

In this tutorial you will learn how to use Group to share default settings —lang prefixes, creative tabs, block/item properties, and tags —across a family of related entries. By the end you will be able to:

  • Create a Group with shared defaults.
  • Register multiple blocks and items through that group.
  • Override group defaults on individual entries when needed.
  • Apply tags to every entry in a group with a single call.
note

If you are only registering one isolated entry, using RegistryCore directly is usually simpler. Group adds value through reuse, not by replacing every entry point.

Step 1 —Decide Whether You Need a Group​

Group is a layer of shared defaults wrapped around RegistryCore. The question it solves is not "can this be registered?" but "should this content family keep repeating the same configuration?"

Ask yourself:

  • Do several entries share the same lang prefix (e.g. "Timer", "Machine")?
  • Should they all appear in the same creative tab?
  • Do they need identical base block or item properties?

If you answered yes to at least two, a Group will save you repetition. If not, register entries directly through RegistryCore.

Step 2 —Create the Group​

Call .group(name) on your RegistryCore instance, configure the shared defaults, and finish with .build():

public static final Group TIMER_GROUP = REGISTRYLIB.group("timers")
        .langPrefix("Timer")
        .blockProperties(p -> p.strength(5.0F, 6.0F))
        .build();

Every block registered through TIMER_GROUP will now inherit the "Timer" lang prefix and strength(5.0F, 6.0F).

Step 3 —Register Entries Through the Group​

Use the group instead of RegistryCore as the starting point:

public static final BlockEntry<TimerBlock> TIMER_TIER_1 = TIMER_GROUP
        .block("tier_1", p -> new TimerBlock(p, 1))
        .initialProperties(() -> Blocks.IRON_BLOCK)
        .simpleItem()
        .register();

tier_1 automatically inherits the lang prefix and the block property modifier from the group.

Step 4 —Understand What Gets Applied Automatically​

Here is the full list of defaults that a Group can apply:

DefaultApplies to
langPrefixAll entries registered through that Group
tabBlockItems, regular Items, and fluid buckets
initialBlockPropertiesAll Blocks registered through that Group
blockPropertiesAll Blocks registered through that Group
initialItemPropertiesAll regular Items registered through that Group
itemPropertiesAll regular Items registered through that Group
addBlockTag(...)All Blocks registered through that Group
addItemTag(...)All Items (and BlockItems) registered through that Group
addFluidTag(...)All Fluids registered through that Group

Override Order​

Group defaults are applied when the Builder is created. Anything you chain after .block(...), .item(...), or .fluid(...) has higher priority:

public static final BlockEntry<TimerBlock> TIMER_TIER_3 = TIMER_GROUP
        .block("tier_3", p -> new TimerBlock(p, 3))
        .initialProperties(() -> Blocks.NETHERITE_BLOCK)  // overrides group's initial properties
        .properties(p -> p.strength(50.0F, 1200.0F))       // overrides group's strength
        .simpleItem()
        .register();

Step 5 —Set Initial Properties Across the Group​

Group.Builder exposes initialBlockProperties(...) and initialItemProperties(...) for setting the base property template:

public static final Group MACHINE_GROUP = REGISTRYLIB.group("machines")
        .langPrefix("Machine")
        .initialBlockProperties(Blocks.IRON_BLOCK)
        .blockProperties(p -> p.strength(5.0F, 6.0F))
        .build();

initialBlockProperties accepts either a Block directly or a Supplier<? extends Block>. It is applied before blockProperties modifiers, so the modifier always has a consistent base.

Step 6 —Apply Tags Across the Group​

Use addBlockTag(...), addItemTag(...), and addFluidTag(...) to tag every entry of the corresponding type. Multiple tags can be passed in a single call, and calls are cumulative:

public static final Group ORE_GROUP = REGISTRYLIB.group("ores")
        .langPrefix("Magic")
        .tab(MY_TAB)
        .addBlockTag(BlockTags.MINEABLE_WITH_PICKAXE, BlockTags.NEEDS_IRON_TOOL)
        .addItemTag(ItemTags.DURABILITY_ENCHANTABLE)
        .build();

Tags are injected at the same time as other defaults —before any per-entry chain. A per-entry .addTag(...) call can always add more tags on top.

tip

For more detail on per-entry tags and recipe datagen, see the Recipes and Tags tutorial.

Common Patterns​

  • Content families —Use Group for a shared lang prefix and tab, then override only the few exceptional values on individual entries.
  • Machine tiers —Use Group for hardness and drop requirements, then add special tooltips or stronger properties on higher-tier entries.
  • Large ore batches —Use Group for mining requirements and creative tab, then configure each ore's drop logic separately.

Boundaries and Pitfalls​

warning
  • Group is not a namespace replacement. It only owns shared defaults and does not change when registration is submitted.
  • A Group tab does not affect bare BlockEntity entries that do not have an Item form.
  • If one entry is clearly an exception, do not force it into the same Group just for visual consistency.

Next Steps​