Guice multibinding with named binding

Question

I have a bunch of Processor. Some are of the same object type but have different configuration. I want to create a set of processor but choose which processor should go in which set. If there a way to do that using multibinding?

public class PostProcessorModule extends AbstractModule {

    public static final String TYPE_A = "TypeA";
    public static final String TYPE_B = "TypeB";

    @Override
    protected void configure() {
        Multibinder<PostProcessor> typeASet =
            Multibinder.newSetBinder(binder(), PostProcessor.class, Names.named("TypeASet"));
        typeASet.addBinding().to(RandomizationPostProcessor.class);  // Only want Type A 
here
        typeASet.addBinding().to(SecondPostProcessor.class);

        Multibinder<PostProcessor> typeBSet =
            Multibinder.newSetBinder(binder(), PostProcessor.class, Names.named("TypeBSet"));
        typeASet.addBinding().to(RandomizationPostProcessor.class);  // Only want Type B 
here
        typeASet.addBinding().to(SecondPostProcessor.class);
    }


    @Provides
    @Singleton
    @Named(TYPE_A)
    public RandomizationPostProcessor getRandomizationPostProcessorA() {

        return RandomizationPostProcessor.builder()
                   .toRandomize(3)
                   .build();
    }

    @Provides
    @Singleton
    @Named(TYPE_B)
    public RandomizationPostProcessor getRandomizationPostProcessorB() {

        return RandomizationPostProcessor.builder()
                   .toRandomize(10)
                   .build();
    }

    @Provides
    @Singleton
    public SecondPostProcessor getSecondPostProcessor() {

        return new SecondPostProcessor();
    }
}

public class Test {
    @Inject
    @Named("TypeASet")
    private final Set<PostProcessor> setA;
    
    @Inject
    @Named("TypeBSet")
    private final Set<PostProcessor> setB;

    public void doSomething() {
        ...
    }
}

RandomizationPostProcessor and SecondPostProcessor implements PostProcessor.

Does multibinding support this? I can't see any function like annotatedWith or similar which we have in normal bind() function. Is writing another function the only way to create custom set?

Answer 1

Sure, you can addBinding to a specific key:

typeASet.addBinding().to(Key.get(RandomizationPostProcessor.class, Names.named(TYPE_A))
typeBSet.addBinding().to(Key.get(RandomizationPostProcessor.class, Names.named(TYPE_B))