EJB: Inject a Singleton with @Startup

Introduction

Keywords

a @Singleton with @Startup bean. Example:

@Startup
@Singleton
class StartupClass {
  public void myPublicMethod() { 
    // do something
  }
  @PostConstruct
  void onStart() { }

  @PreDestroy
  void onStop() { }
}

Problem

with @Inject, I got a Wildfly dependency error:

"WELD-001408: Unsatisfied dependencies for type ..."

How to solve it?

Common

Create an interface with @Local over @Singleton class

// Interface ...
@Local
interface StartupLocalInterface {
  public void myPublicMethod();
}

Declare the interface

@Startup
@Singleton
class StartupClass implements StartupLocalInterface {
  public void myPublicMethod() { 
    // do something
  }
  @PostConstruct
  void onStart() { }

  @PreDestroy
  void onStop() { }
}

1st approach

1. see Common aboce
2. @Inject the interface
   

   @Stateless
   public class MyBean {
     // ...
     @Inject
     StartupLocalInterface startupClass;
     // ...
   }
   

2nd approach

1. see Common above
2. On top of class StartupClass, add an @EJB declaration:
   

    @EJB(name="startupClass", beanInterface=StartupLocalInterface.class)

3. use a context lookup
   

   try {
       Context ctx = new InitialContext();
       StartupLocalInterface t = 
         (StartupLocalInterface) ctx.lookup("java:comp/env/startupClass");
       // do the job...
   } catch (NamingException e) {
       e.printStackTrace();
   }