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Inject a Map of Interface Implementations Keyed by Enum Values

I am using Java 8 with a Play framework. My goal is to inject a map whose keys are enum values and values are implementations of a specific interface.

Here is my enum:

public enum Service {

    HTML("html"), TEXT("txt");

    private String serviceId;
    Service(String serviceId) { this.serviceId = serviceId; }

}

I have Executable interface

public interface Executable { void execute(); }

and two classes that implement it:

public class HtmlWorker implements Executable { ... } 
public class TextWorker implements Executable { ... }

I would like to be able to inject Map<Service, Executable> serviceMap so I can have access to a specific implementation using a Service key:

public class Processor {

  @Inject
  Map<Service, Executable> serviceMap;

  public void doStuff() {
      Executable htmlService = this.serviceMap.get(Service.HTML);
      Executable textService = this.serviceMap.get(Service.TEXT);
      // do more stuff
  }
}

I added bindings to the module class:

public class AppModule extends AbstractModule {

    @Override
    protected void configure() {
        MapBinder<Service, Executable> serviceBinder = MapBinder
          .newMapBinder(binder(), Service.class, Executable.class);

        serviceBinder.addBinding(Service.HtmlService).to(HtmlWorker.class);
        serviceBinder.addBinding(Service.TextService).to(TextWorker.class);

    }

The problem is that serviceMap is never injected and it is always null inside Processor . What am I missing?

According to the official MapBinder documentation the MapBinder.addBinding should take the map's key.

As far as concerning your provided example what about changing AbstractModule 's code from:

serviceBinder.addBinding(Service.HtmlService).to(HtmlWorker.class);
serviceBinder.addBinding(Service.TextService).to(TextWorker.class);

to

serviceBinder.addBinding(Service.HTML).to(HtmlWorker.class); // <-- see the enum constant here?
serviceBinder.addBinding(Service.TEXT).to(TextWorker.class);

Anyway I don't know where the class Service.HtmlService in your example comes from since you didn't state it anywhere.

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