MVVM sample: TaskDetailViewModel

task-detail-view-model.java

// UNSCOPED
public class TaskDetailViewModel
        extends SingleTaskViewModel {
    private final Backstack backstack;
    private final MessageQueue messageQueue;

    @Inject
    TaskDetailViewModel(Context context, TasksRepository tasksRepository, 
                        Backstack backstack, MessageQueue messageQueue) {
        super(context, tasksRepository);
        this.backstack = backstack;
        this.messageQueue = messageQueue;
    }

    public void startEditTask() {
        backstack.goTo(AddEditTaskKey.create(getTaskId())); // navigate to
    }
  
    public void deleteTask() {
        super.deleteTask();
        messageQueue.pushMessageTo(TasksKey.create(), new TasksViewModel.DeletedTaskMessage());
        backstack.setHistory(History.single(TasksKey.create()), StateChange.BACKWARD);  // navigate back
    }
}