This snippet of code is extracted for Google's sample of MPV for Android. https://github.com/googlesamples/android-architecture/tree/todo-mvp/ - At the beginning of the project we create the "BasePresenter" interface that every Presenter in our proj

BasePresenter.java

public interface BasePresenter {

    void start();

}

BaseView.java

public interface BaseView<T> {

    void setPresenter(T presenter);

}

TasksActivity.java

public class TasksActivity extends AppCompatActivity {



    private TasksPresenter mTasksPresenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tasks_act);

        TasksFragment tasksFragment =
                (TasksFragment) getSupportFragmentManager().findFragmentById(R.id.contentFrame);
        if (tasksFragment == null) {
            // Create the fragment
            tasksFragment = TasksFragment.newInstance();
            ActivityUtils.addFragmentToActivity(
                    getSupportFragmentManager(), tasksFragment, R.id.contentFrame);
        }

        // Create the presenter and attach it to our View (Fragment)
        mTasksPresenter = new TasksPresenter(
                Injection.provideTasksRepository(getApplicationContext()), tasksFragment);

        
    }

  

  
}

TasksContract.Java

public interface TasksContract {
  
  interface Presenter extends BasePresenter {
      //the presenter functions that will be triggered from the view 
      //eg. Bussines logic or fetching data from the backend
      //based on the user actions or a View Lifecycle.

        void result(int requestCode, int resultCode);

        void loadTasks(boolean forceUpdate);

        void addNewTask();

        void openTaskDetails(@NonNull Task requestedTask);

        void completeTask(@NonNull Task completedTask);

        void activateTask(@NonNull Task activeTask);

        void clearCompletedTasks();

        void setFiltering(TasksFilterType requestType);

        TasksFilterType getFiltering();
    }
    //this presenter between <Presenter> is what we just declared in the above interface
    interface View extends BaseView<Presenter> {
      //triggered functions from the presenter to update the UI 
        void setLoadingIndicator(boolean active);

        void showTasks(List<Task> tasks);

        void showAddTask();

        void showTaskDetailsUi(String taskId);

        void showTaskMarkedComplete();

        void showTaskMarkedActive();

        void showCompletedTasksCleared();

        void showLoadingTasksError();

        void showNoTasks();

        void showActiveFilterLabel();

        void showCompletedFilterLabel();

        void showAllFilterLabel();

        void showNoActiveTasks();

        void showNoCompletedTasks();

        void showSuccessfullySavedMessage();

        boolean isActive();

        void showFilteringPopUpMenu();
    }
}

TasksFragment.java

public class TasksFragment extends Fragment implements TasksContract.View {
    
      // our refrence of the presenter 
      private TasksContract.Presenter mPresenter;
      
      //triggering a presenter function based on the fragment lifecycle
       @Override
    public void onResume() {
        super.onResume();
        mPresenter.start();
    }
  
    //initializing the presenter from the method we impelmented from the Contract.View after the Presenter 
    //class triggered this function
 @Override
    public void setPresenter(@NonNull TasksContract.Presenter presenter) {
        mPresenter = checkNotNull(presenter);
    }
    
  //at anytime we could trigger any function of the presenter class using it's instance eg.
   mPresenter.completeTask(completedTask);
  
}

TasksPresenter.java

public class TasksPresenter implements TasksContract.Presenter {
    //refrence for the repository that is resposible for fetching the model data from any datasource
    private final TasksRepository mTasksRepository;
    //refrence of the View to trigger the functions after proccessing the task
    private final TasksContract.View mTasksView;
    
    // Presenter's Constructor the intialize the view attached to it 
    //and the repository and setting the view to this Presenter
     public TasksPresenter(@NonNull TasksRepository tasksRepository, @NonNull TasksContract.View tasksView) {
        mTasksRepository = checkNotNull(tasksRepository, "tasksRepository cannot be null");
        mTasksView = checkNotNull(tasksView, "tasksView cannot be null!");

        mTasksView.setPresenter(this);
    }
    
    //triggring a method based on the view lifecycle
      @Override
    public void start() {
        loadTasks(false);
    }
    
    //anytime we want to trigger a function inside our view we use our view refrence eg.
    mTasksView.showSuccessfullySavedMessage();
    
  
}