Example.java

// BasePresenter.java (Base class for all our Presenters)
public abstract class BasePresenter<V> {

  private WeakReference<V> mView;

  public void bindView(@NonNull V view) {
    mView = new WeakReference<>(view);
  }

  public void unbindView() {
    mView = null;
  }

  public V getView() {
    if (mView == null) {
      return null;
    } else {
      return mView.get();
    }
  }

  protected final boolean isViewAttached() {
    return mView != null && mView.get() != null;
  }
}

// IForgotPasswordView.java (view interface)
public interface IForgotPasswordView {
  void showLoading();
  void hideLoading();
  void setEmailText(String email);
  void showEmailNotValidError();
  void showPasswordRequestOk(String message);
  void showPasswordRequestFail();
}

// ForgotPasswordFragment.java (view implementation)
public class ForgotPasswordFragment implements IForgotPasswordView,
        View.OnClickListener {

  // Triggered by the user clicking a button
  public void onResetPasswordClick() {
    String email = mEmailEditText.getText().toString();
    
    // Forward all logic to the Presenter
    mPresenter.requestPasswordChange(email);
  }
  
}

// ForgotPasswordPresenter.java
public class ForgotPasswordPresenter extends BasePresenter<IForgotPasswordView> {
  
  public void requestPasswordChange(String email) {
    if (!Utils.isEmailValid(email)) {
      
      // Make sure the view is still alive before trying to access it
      if(isViewAttached()) {
        getView().showEmailNotValidError();    
      }
    } else {
      requestPasswordChangeAsync(email);
    }
  }
  
  private void requestPasswordChangeAsync(String email) {
    
    // Update the view's UI elements
    if(isViewAttached()) {
      getView().hideKeyboard();
      getView().showLoading();
      
      // Call our API (results are posted back on an EventBus)
      api.forgotPassword(email);
    }
    
  }

  // Subscription to the event bus
  @Subscribe
  public void onEvent(final Event event) {

    if (isViewAttached()) {
    
      // Update the view's UI elements
      getView().hideLoading();
          
      switch (event.getType()) {
        case FORGOT_PASSWORD_OK:
          getView().showPasswordRequestOk((String) event.getData());
          break;
        case FORGOT_PASSWORD_FAILED:
          getView().showPasswordRequestFail();
          break;
        }
      }
  }
}