Revised example of a service that hides implementation details by using a private inner class.

service_example3.java

public class ExampleClientService {

  private final List<ExampleListener> listeners = new ArrayList<ExampleListener>();
  private final List<Example> examples = new ArrayList<Example>();

  private final ExampleListenerImpl listener = new ExampleListenerImpl();

  public ExampleClientService(ExamplesManager examplesManager) {
    examplesManager.addExampleListener(this.listener);
  }

  public void addExampleListener(ExampleListener listener) {
    listeners.add(listener);
  }

  public void removeExampleListener(ExampleListener listener) {
    listeners.remove(listener);
  }

  private void copyExample(Example example) {
    // Copy Example into list and then send list to all listeners.
  }

  private class ExampleListenerImpl implements ExampleListener {

    /** {@inheritDoc} */
    @Override
    public void goodExampleDispatched(Example example) {
      copyExample(example);
    }

    /** {@inheritDoc} */
    @Override
    public void badExampleDispatched(Example example) {
      copyExample(example);
    }

  }

}