Question

I have a method annotated with @Provides in my Guice config, but it doesn’t work.

public class GuiceConfig extends GuiceServletContextListener {

  ...

  @Provides @RequestScoped
  EntityManager provideEntityManger() {
    return entityManagerFactory.createEntityManager();
  }

}

When I run my application I get the following error:

com.google.inject.CreationException:
Guice creation errors:<|<|1) No
implementation for
javax.persistence.EntityManager was
bound.<| while locating
javax.persistence.EntityManager<|
for parameter 0 at
com.someclass.of.myproject

Answer 1

The main problem here is that you’re using @Provides incorrectly. An @Provides method must be in one of the Modules that you use when initializing Guice… you can’t just put it in the GuiceServletContextListener.