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Redirection: @Redirect

The redirector lets you redirect a method call to your own method, as shown below:

@Redirect(method = "methodToInject", at = @At(value = "INVOKE", target = "calledClass;calledMethod"))
  private T redirect(calledObject, methodArguments) {
    //your code
  }

Redirecting a static method​

A static method redirector takes the same arguments as the target method.

This redirects the ItemStack::fromTag(ListTag) call inside SimpleInventory::readTags so that it returns null:

@Mixin(SimpleInventory.class)
abstract class SimpleInventoryMixin {
    @Redirect(method = "readTags",
              at = @At(value = "INVOKE_ASSIGN", target = "Lnet/minecraft/item/ItemStack;fromTag(Lnet/minecraft/nbt/ListTag;)Lnet/minecraft/item/ItemStack;"))
    private static ItemStack returnNull(ListTag tag) {
        return null;
    }
}

Redirecting an instance method​

Instance method redirectors work like static ones, but their first argument is always the object on which the target method is called.

This redirects the Entity::dropItem(ItemConvertible, int) call inside Entity::dropItem(ItemConvertible) so that no item (air) is dropped where a diamond would have been:

@Mixin(Entity.class)
abstract class EntityMixin {
    @Redirect(method = "dropItem",
              at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;dropItem(Lnet/minecraft/item/ItemConvertible;I)Lnet/minecraft/entity/ItemEntity;"))
    private ItemEntity replaceDroppedItem(Entity droppingEntity, ItemConvertible item, int yOffset) {
        return droppingEntity.dropItem(item == Items.DIAMOND ? Items.AIR : item, yOffset);
    }
}

INVOKE_STRING​

The INVOKE_STRING injection point matches a target that takes a single string argument in a method call. The string to match is specified through the args property of At.

This redirects the Profiler::push call inside MinecraftClient::render that receives tick, changing the location passed to that call:

@Mixin(MinecraftClient.class)
abstract class MinecraftClientMixin {
    @Redirect(method = "render",
              at = @At(value = "INVOKE_STRING",
                       target = "Lnet/minecraft/util/profiler/Profiler;push(Ljava/lang/String;)V",
                       args = "ldc=tick"))
    private void redirectPush(Profiler profiler, String location) {
        profiler.push("modified tick");
        System.out.println(location);
    }
}