MainPresenterImpl.java

public class MainPresenterImpl implements MainContract.Presenter {

    private final MainContract.View mView;
    private final DataManager mDataManager;

    // Constructor with view and datamanger parameters.
    public MainPresenterImpl(MainContract.View view, DataManager dataManager) {
        this.mView = view;
        mDataManager = dataManager;
        mView.setPresenter(this); // Set presenter to the mView.
    }

    //BEGIN
    // Implementation of MainContract.Presenter
  
    @Override
    public void addNote(String note) {
        if(note != null && note.length() > 0)
            mView.updateView(mDataManager.addNote(new Note(mDataManager.getNoteListSize() + 1, note)));
    }

    @Override
    public void removeNote(Note note) {
        mView.updateView(mDataManager.removeNote(note));
    }

    @Override
    public void getAllNotes() {
        mView.showProgress();

        // Delay to simulate api as remote api.
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                mView.updateView(mDataManager.getAllNotes());
                mView.hideProgress();
            }
        }, 3000);
    }

    @Override
    public void clearAll() {
        mView.showProgress();

        // Delay to simulate api as remote api.
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                mView.updateView(mDataManager.removeAllNotes());
                mView.hideProgress();
            }
        }, 3000);
    }
  
    // END
}