Package net.fabricmc.loader.api

Interface ObjectShare

public interface ObjectShare
Object share for inter-mod communication, obtainable through FabricLoader.getObjectShare().

The share allows mods to exchange data without directly referencing each other. This makes simple interaction easier by eliminating any compile- or run-time dependencies if the shared value type is independent of the mod (only Java/game/Fabric types like collections, primitives, String, Consumer, Function, ...).

Active interaction is possible as well since the shared values can be arbitrary Java objects. For example exposing a Runnable or Function allows the "API" user to directly invoke some program logic.

It is required to prefix the share key with the mod id like mymod:someProperty. Mods should not modify entries by other mods. The share is thread safe.

  • Method Details

    • get

      Object get(String key)
      Get the value for a specific key.

      Java 16 introduced a convenient syntax for type safe queries that combines null check, type check and cast: 

       if (FabricLoader.getInstance().getObjectShare().get("someMod:someValue") instanceof String value) {
   // use value here
 }

      A generic type still needs a second unchecked cast due to erasure: 

       if (FabricLoader.getInstance().getObjectShare().get("mymod:fuel") instanceof Consumer<?> c) {
   ((Consumer<ItemStack>) c).accept(someStack);
 }

      Consider using whenAvailable(java.lang.String, java.util.function.BiConsumer<java.lang.String, java.lang.Object>) instead if the value may not be available yet. The mod load order is undefined, so entries that are added during the same load phase should be queried in a later phase or be handled through whenAvailable(java.lang.String,java.util.function.BiConsumer<java.lang.String,java.lang.Object>).

      Parameters:
      key - key to query, format modid:subkey
      Returns:
      value associated with the key or null if none

    • whenAvailable

      void whenAvailable(String key, BiConsumer<String,Object> consumer)
      Request being notified when a key/value becomes available.

      This is primarily intended to resolve load order issues, when there is no good time to call get(java.lang.String).

      If there is already a value associated with the key, the consumer will be invoked directly, otherwise when one of the put methods adds a value for the key. The invocation happens on the thread calling whenAvailable(java.lang.String, java.util.function.BiConsumer<java.lang.String, java.lang.Object>) or on whichever thread calls put with the same key.

      The request will only act once, not if the value changes again.

      Example use: 

       FabricLoader.getInstance().getObjectShare().whenAvailable("someMod:someValue", (k, v) -> {
   if (v instanceof String value) {
     // use value
   }
 });
      Parameters:
      key - key to react upon, format modid:subkey

    • put

      Object put(String key, Object value)
      Set the value for a specific key.
      Parameters:
      key - key to add a value for, format modid:subkey
      value - value to add, must not be null
      Returns:
      previous value associated with the key, null if none

    • putIfAbsent

      Object putIfAbsent(String key, Object value)
      Set the value for a specific key if there isn't one yet.

      This is an atomic operation, thus thread safe contrary to using get+put.

      Parameters:
      key - key to add a value for, format modid:subkey
      value - value to add, must not be null
      Returns:
      previous value associated with the key, null if none and thus the entry changed

    • remove

      Object remove(String key)
      Remove the value for a specific key.
      Parameters:
      key - key to remove the value for, format modid:subkey
      Returns:
      previous value associated with the key, null if none