Implement interface with multiple EJBs

Question

Given the following interface:

public interface MyRunnable {   
    public MyResponse run(int x);
}

It is implemented by two @Stateless beans:

@Stateless
public class Bean1 implements MyRunnable {

     public MyResponse run(int x) {
           // some logic
     }
}


@Stateless
public class Bean2 implements MyRunnable {

     public MyResponse run(int x) {
           // some logic
     }
}

Now, I want to run one bean or the other depending on a condition. What is the best way to achieve that?

This is what I tried, unsuccessfully:

@Stateless
@LocalBean
public class MainBean {

   @Inject 
   private Bean1 bean1;

   @Inject 
   private Bean2 bean2;

   public void someMethod(int y) {

          MyRunnable runnable = null;
          if (y == 1)
              runnable = bean1;
          else
              runnable = bean2;

          runnable.run(5);

   }
}

The code compiles, but it gives me (in Wildfly) a startup error:

WELD-001408: Unsatisfied dependencies for type Bean1 with qualifiers @Default

UPDATE Something that I noticed; if I remove implements MyRunnable from the beans there are no startup errors.

Possible duplicate of [Stateless EJB implements interface injection failed](https://stackoverflow.com/questions/34352909/stateless-ejb-implements-interface-injection-failed) — Flown, Feb 19 '19 at 21:45
@Flown the question you are referring to only deals with one bean, in my case it is multiple. Do you know how to fix this problem? — ps0604, Feb 19 '19 at 21:50

score 6 · Accepted Answer · answered Feb 19 '19 at 22:02

Since you're implementing the same interface in Bean1 and Bean2 they are mapped to to MyRunnable (they are now @Local beans). Since Weld does not know how to resolve this you would need to specify which bean you would like to inject. The proper way would be:

@Stateless
public class MyBean {

  @EJB(beanName = "Bean1")
  MyRunnable bean1;

  @EJB(beanName = "Bean2")
  MyRunnable bean2;

  public void run() {
    MyRunnable r = Math.random() < 0.5d ? bean1 : bean2;
    r.run(10);
  }
}

Implement interface with multiple EJBs

1 Answers1