Я пытаюсь выяснить, почему наблюдатель LiveData для getAllGoals() не запускается сразу во фрагменте, когда я обновляю запись. Однако наблюдатель вызывается только после переключения на другой фрагмент с использованием навигации нижней вкладки и последующего возврата к исходному фрагменту.
Рассматриваемый фрагмент: MyGoalsFragment. java
public class MyGoalsFragment extends Fragment implements MyGoalsAdapter.MyGoalsCallback {
FragmentMyGoalsBinding myGoalsBinding;
private MyGoalsViewModel myGoalsViewModel;
MyGoalsAdapter myGoalsAdapter;
ConstraintSet smallConstraintSet = new ConstraintSet();
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
myGoalsViewModel = new ViewModelProvider(getActivity(), ViewModelProvider.AndroidViewModelFactory.getInstance(getActivity().getApplication())).get(MyGoalsViewModel.class);
myGoalsBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_my_goals, container, false);
myGoalsBinding.recyclerView2.setLayoutManager(new LinearLayoutManager(getActivity()));
DrawerLayout drawerLayout = (DrawerLayout) getActivity().findViewById(R.id.drawer_layout);
myGoalsBinding.menu.setOnClickListener(v -> {
drawerLayout.openDrawer(GravityCompat.START);
});
TransitionManager.beginDelayedTransition(myGoalsBinding.recyclerView2);
myGoalsAdapter = new MyGoalsAdapter();
myGoalsAdapter.setCallback(this);
myGoalsAdapter.setContext(getActivity());
myGoalsAdapter.setRecyclerView(myGoalsBinding.recyclerView2);
myGoalsBinding.recyclerView2.setAdapter(myGoalsAdapter);
myGoalsBinding.floatingActionButton.setOnClickListener(v -> {
startActivity(new Intent(getActivity(), CreateGoalActivity.class));
getActivity().finish();
});
enableSwipeToDeleteAndUndo();
myGoalsBinding.recyclerView2.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (dy > 0 && myGoalsBinding.floatingActionButton.getVisibility() == View.VISIBLE) {
myGoalsBinding.floatingActionButton.hide();
} else if (dy < 0 && myGoalsBinding.floatingActionButton.getVisibility() != View.VISIBLE) {
myGoalsBinding.floatingActionButton.show();
}
}
});
myGoalsViewModel.getAllGoals().observe(getViewLifecycleOwner(), new Observer<List<Goal>>() {
@Override
public void onChanged(List<Goal> goals) {
myGoalsAdapter.submitList(goals); // This observer is not called even after updating a record
}
});
return myGoalsBinding.getRoot();
}
@Override
public void editGoalCallback(Goal goal) {
Intent intent = new Intent(getActivity(), CreateGoalActivity.class);
Bundle bundle = new Bundle();
bundle.putSerializable("goal", goal);
intent.putExtras(bundle);
startActivity(intent);
}
@Override
public void goalCheckBoxCallback(Goal goal) {
myGoalsViewModel.updateGoal(goal);
}
private void enableSwipeToDeleteAndUndo() {
SwipeToDeleteCallback swipeToDeleteCallback = new SwipeToDeleteCallback(getActivity()) {
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int i) {
if(i==ItemTouchHelper.LEFT) {
Goal tempGoal = myGoalsAdapter.getGoalAt(viewHolder.getAdapterPosition());
myGoalsViewModel.deleteGoal(tempGoal);
Snackbar.make(myGoalsBinding.rootConstraintLayout, "Goal Deleted", Snackbar.LENGTH_LONG)
.setAction("Undo", v -> {
myGoalsViewModel.insertGoal(tempGoal);
})
.setActionTextColor(getActivity().getResources().getColor(R.color.arcticLimeGreen))
.show();
}else if(i==ItemTouchHelper.RIGHT){
Goal tempGoal = myGoalsAdapter.getGoalAt(viewHolder.getAdapterPosition());
if(tempGoal.isCompleted())
tempGoal.setCompleted(false);
else
tempGoal.setCompleted(true);
TransitionManager.beginDelayedTransition(myGoalsBinding.recyclerView2);
myGoalsViewModel.updateGoal(tempGoal); // This is where the update is called
}
}
};
ItemTouchHelper itemTouchhelper = new ItemTouchHelper(swipeToDeleteCallback);
itemTouchhelper.attachToRecyclerView(myGoalsBinding.recyclerView2);
}
}
Модель представления MyGoals:
public class MyGoalsViewModel extends AndroidViewModel {
private NoteRepository repository;
private LiveData<List<Goal>> allGoals;
public MyGoalsViewModel(@NonNull Application application) {
super(application);
repository = new NoteRepository(application);
allGoals = repository.getAllGoals();
}
public LiveData<List<Goal>> getAllGoals(){
return allGoals;
}
public void deleteGoal(Goal goal){repository.deleteGoal(goal);}
public void insertGoal(Goal goal){repository.insertGoal(goal);}
public void updateGoal(Goal goal){repository.updateGoal(goal);}
}
Репозиторий:
public class NoteRepository {
private String DB_NAME = "db_task";
Context context;
private GoalDao goalDao;
private LiveData<List<Goal>> allGoals;
private NoteDatabase noteDatabase;
public NoteRepository(Context context) {
noteDatabase = NoteDatabase.getInstance(context);
goalDao = noteDatabase.goalDao();
allGoals = goalDao.getAllGoals();
this.context = context;
}
public void insertGoal(Goal goal){
new InsertGoalAsyncTask(goalDao).execute(goal);
}
public void deleteGoal(Goal goal){
new DeleteGoalAsyncTask(goalDao).execute(goal);
}
public void updateGoal(Goal goal){
new UpdateGoalAsyncTask(goalDao).execute(goal);
}
public void deleteAllGoals(){
new DeleteAllGoalAsyncTask(goalDao).execute();
}
public LiveData<List<Goal>> getAllGoals(){
return allGoals;
}
private static class InsertGoalAsyncTask extends AsyncTask<Goal,Void,Void>{
private GoalDao goalDao;
private InsertGoalAsyncTask(GoalDao goalDao){
this.goalDao = goalDao;
}
@Override
protected Void doInBackground(Goal... goals) {
goalDao.insert(goals[0]);
return null;
}
}
private static class DeleteGoalAsyncTask extends AsyncTask<Goal,Void,Void>{
private GoalDao goalDao;
private DeleteGoalAsyncTask(GoalDao goalDao){
this.goalDao = goalDao;
}
@Override
protected Void doInBackground(Goal... goals) {
goalDao.delete(goals[0]);
return null;
}
}
private static class UpdateGoalAsyncTask extends AsyncTask<Goal,Void,Void>{
private GoalDao goalDao;
private UpdateGoalAsyncTask(GoalDao goalDao){
this.goalDao = goalDao;
}
@Override
protected Void doInBackground(Goal... goals) {
goalDao.update(goals[0]);
return null;
}
}
private static class DeleteAllGoalAsyncTask extends AsyncTask<Void,Void,Void>{
private GoalDao goalDao;
private DeleteAllGoalAsyncTask(GoalDao goalDao){
this.goalDao = goalDao;
}
@Override
protected Void doInBackground(Void... voids) {
goalDao.deleteAllGoals();
return null;
}
}
}
Класс DAO:
@Dao
public interface GoalDao {
@Insert
void insert(Goal goal);
@Update
void update(Goal goal);
@Delete
void delete(Goal goal);
@Query("DELETE from goal_table")
void deleteAllGoals();
@Query("Select * from goal_table order by end_date")
LiveData<List<Goal>> getAllGoals();
}
У меня эта проблема состоит из 2 фрагментов, и их 2 другие фрагменты, у которых нет этой проблемы, с той же самой реализацией. Почему наблюдатель не вызывается, как только я обновляю запись во фрагменте MyGoals?