MainActivity.java

public class MainActivity extends AppCompatActivity implements MainContract.View, View.OnClickListener {

    // Contract Presenter
    private MainContract.Presenter mPresenter;
    ......
    // Other fields

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // initialization of ui elements and other fields
        ......
        ......
    }
    
    /**
    * BEGIN
    * Implemented methods from MainContract.View interface
    */

    // Setup contract presenter here.
    @Override
    public void setPresenter(MainContract.Presenter presenter) {
        mPresenter = presenter;
    }

    // Show loading progress dialog.
    @Override
    public void showProgress() {
        mProgressDialog = new ProgressDialog(this);
        mProgressDialog.setCancelable(false);
        mProgressDialog.setMessage("Loading");
        mProgressDialog.show();
    }

    // Hide loading progress dialog.
    @Override
    public void hideProgress() {
        if (mProgressDialog != null) {
            mProgressDialog.dismiss();
            mProgressDialog = null;
        }
    }

    // Displays all the notes which are saved in note list.
    @Override
    public void updateView(List<Note> items) {
        mMainAdapter.updateData(items);
    } 
    
    /**
    * END
    */
    .....

}