In this part I try to add one feature in my app and fix one problem, I would like to save the recyclerview position so when click and navigate to details fragment and click back, this should back to the same position, the issue here is when I click back I see the items overlapping, there are about 8 items and it starts from next list position, while I searching for the solution of this issue, I found this answer then I decided to add the dependencies of recyclerview separately implementation "androidx.recyclerview:recyclerview:1.2.1" to use this feature
adapter.setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY);
but it doesn't work, the next GIF describe the problem
and this example of the app with this feature
HomeFragment
@AndroidEntryPoint
public class HomeFragment extends Fragment {
private FragmentHomeBinding binding;
private PostViewModel postViewModel;
public static final String TAG = "HomeFragment";
private PostAdapter adapter;
private List<Item> itemArrayList;
private GridLayoutManager titleLayoutManager, gridLayoutManager;
WrapContentLinearLayoutManager layoutManager;
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.homeRecyclerView.addOnItemTouchListener(new RecyclerItemClickListener(requireContext(),
binding.homeRecyclerView, new RecyclerItemClickListener.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
Item item = itemArrayList.get(position);
if (Objects.requireNonNull
(Navigation.findNavController(requireView())
.getCurrentDestination()).getId() == R.id.nav_home) {
Navigation.findNavController(requireView())
.navigate(HomeFragmentDirections.actionNavHomeToDetailsFragment(item));
}
}
@Override
public void onLongItemClick(View view, int position) {
}
}));
}
public View onCreateView(@NonNull LayoutInflater inflater,
@Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
binding = FragmentHomeBinding.inflate(inflater, container, false);
setHasOptionsMenu(true);
postViewModel = new ViewModelProvider(this).get(PostViewModel.class);
postViewModel.finalURL.setValue(Constants.getBaseUrl() "?key=" Constants.getKEY());
itemArrayList = new ArrayList<>();
adapter = new PostAdapter(getContext(), itemArrayList, this, postViewModel);
layoutManager = new WrapContentLinearLayoutManager(requireContext(),
LinearLayoutManager.VERTICAL, false);
titleLayoutManager = new GridLayoutManager(getContext(), 2);
gridLayoutManager = new GridLayoutManager(getContext(), 3);
// binding.homeRecyclerView.setAdapter(adapter);
binding.shimmerLayout.setVisibility(View.VISIBLE);
binding.homeRecyclerView.setVisibility(View.INVISIBLE);
adapter.setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY);
postViewModel.recyclerViewLayoutMT.observe(getViewLifecycleOwner(), layout -> {
Log.w(TAG, "getSavedLayout: called");
switch (layout) {
case "cardLayout":
binding.loadMoreBtn.setVisibility(View.VISIBLE);
binding.homeRecyclerView.setLayoutManager(layoutManager);
binding.homeRecyclerView.setAdapter(adapter);
adapter.setViewType(0);
break;
case "cardMagazineLayout":
binding.loadMoreBtn.setVisibility(View.VISIBLE);
binding.homeRecyclerView.setLayoutManager(layoutManager);
binding.homeRecyclerView.setAdapter(adapter);
adapter.setViewType(1);
break;
case "titleLayout":
binding.loadMoreBtn.setVisibility(View.GONE);
binding.homeRecyclerView.setLayoutManager(titleLayoutManager);
binding.homeRecyclerView.setAdapter(adapter);
adapter.setViewType(2);
break;
case "gridLayout":
binding.loadMoreBtn.setVisibility(View.GONE);
binding.homeRecyclerView.setLayoutManager(gridLayoutManager);
binding.homeRecyclerView.setAdapter(adapter);
adapter.setViewType(3);
}
});
if (Utils.hasNetworkAccess(requireContext())) {
postViewModel.getPosts();
postViewModel.postListMutableLiveData.observe(getViewLifecycleOwner(), postList -> {
itemArrayList.addAll(postList.getItems());
binding.shimmerLayout.stopShimmer();
binding.shimmerLayout.setVisibility(View.GONE);
binding.homeRecyclerView.setVisibility(View.VISIBLE);
adapter.notifyDataSetChanged();
Log.e(TAG, "ItemsArrayList :" itemArrayList.get(0).getTitle());
});
} else {
binding.shimmerLayout.setVisibility(View.VISIBLE);
// binding.shimmerLayout.startShimmer();
if (postViewModel.getAllItemsFromDataBase == null) {
noInternetConnectionLayout();
} else {
// Log.e(TAG, "RoomDB Items size :" itemsDatabase.itemDAO().getAlItems());
binding.shimmerLayout.stopShimmer();
binding.shimmerLayout.setVisibility(View.GONE);
binding.emptyView.setVisibility(View.GONE);
binding.homeRecyclerView.setVisibility(View.VISIBLE);
postViewModel.getAllItemsFromDataBase.observe(getViewLifecycleOwner(), items -> {
if (items.isEmpty()) {
noInternetConnectionLayout();
} else {
binding.loadMoreBtn.setVisibility(View.GONE);
itemArrayList.addAll(items);
adapter.notifyDataSetChanged();
}
});
}
}
postViewModel.errorCode.observe(getViewLifecycleOwner(), errorCode -> {
if (errorCode == 400) {
Snackbar.make(requireView(), R.string.lastPost, Snackbar.LENGTH_LONG).show();
} else {
binding.homeRecyclerView.setVisibility(View.INVISIBLE);
binding.emptyView.setVisibility(View.VISIBLE);
}
});
binding.loadMoreBtn.setOnClickListener(view -> {
AlertDialog dialog = Utils.setProgressDialog(requireContext());
postViewModel.isLoading.observe(getViewLifecycleOwner(), isLoading -> {
if (isLoading) {
dialog.show();
} else {
dialog.dismiss();
}
});
if (Utils.hasNetworkAccess(requireContext())) {
postViewModel.getPosts();
// Log.w(TAG, "loadMoreBtn: " dialog.isShowing());
} else {
postViewModel.isLoading.postValue(true);
postViewModel.getAllItemsFromDataBase.getValue();
postViewModel.isLoading.postValue(false);
}
});
return binding.getRoot();
}
private void noInternetConnectionLayout() {
binding.shimmerLayout.stopShimmer();
binding.shimmerLayout.setVisibility(View.GONE);
binding.homeRecyclerView.setVisibility(View.GONE);
binding.emptyView.setVisibility(View.VISIBLE);
}
@Override
public void onDestroyView() {
super.onDestroyView();
itemArrayList.clear();
binding = null;
}
@Override
public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
inflater.inflate(R.menu.main, menu);
super.onCreateOptionsMenu(menu, inflater);
SearchManager searchManager = (SearchManager) requireContext().getSystemService(Context.SEARCH_SERVICE);
SearchView searchView = (SearchView) menu.findItem(R.id.app_bar_search).getActionView();
searchView.setSearchableInfo(searchManager.getSearchableInfo(requireActivity().getComponentName()));
searchView.setQueryHint(getResources().getString(R.string.searchForPosts));
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String keyword) {
if (keyword.isEmpty()) {
Snackbar.make(requireView(), "please enter keyword to search", Snackbar.LENGTH_SHORT).show();
}
if (Utils.hasNetworkAccess(requireContext())) {
itemArrayList.clear();
postViewModel.getItemsBySearch(keyword);
adapter.notifyDataSetChanged();
} else {
postViewModel.getItemsBySearchInDB(keyword);
postViewModel.getItemsBySearchMT.observe(getViewLifecycleOwner(), items ->
{
Log.d(TAG, "onQueryTextSubmit database called");
itemArrayList.clear();
itemArrayList.addAll(items);
adapter.notifyDataSetChanged();
}
);
}
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
return false;
}
});
searchView.setOnCloseListener(() -> {
if (Utils.hasNetworkAccess(requireContext())) {
Log.d(TAG, "setOnCloseListener: called");
itemArrayList.clear();
binding.emptyView.setVisibility(View.GONE);
binding.homeRecyclerView.setVisibility(View.VISIBLE);
postViewModel.getPosts();
adapter.notifyDataSetChanged();
} else {
Log.d(TAG, "setOnCloseListener: called");
binding.emptyView.setVisibility(View.GONE);
binding.homeRecyclerView.setVisibility(View.VISIBLE);
postViewModel.getAllItemsFromDataBase.observe(getViewLifecycleOwner(), items ->
{
itemArrayList.addAll(items);
adapter.notifyDataSetChanged();
}
);
}
return false;
});
postViewModel.searchError.observe(getViewLifecycleOwner(), searchError -> {
if (searchError) {
Toast.makeText(requireContext(),
"There's no posts with this keyword", Toast.LENGTH_LONG).show();
}
});
}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
if (item.getItemId() == R.id.change_layout) {
changeAndSaveLayout();
return true;
}
return super.onOptionsItemSelected(item);
}
The ViewModel
@HiltViewModel
public class PostViewModel extends ViewModel {
public static final String TAG = "PostViewModel";
private final com.blogspot.abtallaldigital.data.Repository repository;
public final MutableLiveData<PostList> postListMutableLiveData = new MutableLiveData<>();
public final MutableLiveData<String> finalURL = new MutableLiveData<>();
public final MutableLiveData<String> token = new MutableLiveData<>();
public final MutableLiveData<String> label = new MutableLiveData<>();
public final MutableLiveData<Integer> errorCode = new MutableLiveData<>();
public final MutableLiveData<Boolean> searchError = new MutableLiveData<>();
public final LiveData<List<Item>> getAllItemsFromDataBase;
public final MutableLiveData<List<Item>>
getItemsBySearchMT = new MutableLiveData<>();
public final MutableLiveData<Boolean> isLoading = new MutableLiveData<>();
public final MutableLiveData<String> recyclerViewLayoutMT = new MutableLiveData<>();
private final Utils.DataStoreRepository dataStoreRepository;
public final MutableLiveData<Integer> currentDestination = new MutableLiveData<>();
// public MutableLiveData<Boolean> ifAnythingWrongHappened = new MutableLiveData<>();
@Inject
public PostViewModel(Repository repository, Utils.DataStoreRepository dataStoreRepository) {
this.repository = repository;
getAllItemsFromDataBase = repository.localDataSource.getAllItems();
this.dataStoreRepository = dataStoreRepository;
dataStoreRepository.readLayoutFlow
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new FlowableSubscriber<String>() {
@Override
public void onSubscribe(@NonNull Subscription s) {
s.request(Long.MAX_VALUE);
}
@Override
public void onNext(String layout) {
if (layout != null) {
recyclerViewLayoutMT.setValue(layout);
}
}
@Override
public void onError(Throwable t) {
Log.e(TAG, "onError: " t.getMessage());
Log.e(TAG, "onError: " t.getCause());
}
@Override
public void onComplete() {
}
});
dataStoreRepository.readCurrentDestination
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.firstOrError().subscribeWith(new SingleObserver<Integer>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onSuccess(@NonNull Integer destination) {
currentDestination.setValue(destination);
}
@Override
public void onError(@NonNull Throwable e) {
Log.e(TAG, "onError: " e.getMessage());
}
});
}
public void saveRecyclerViewLayout(String layout) {
dataStoreRepository.saveRecyclerViewLayout("recyclerViewLayout", layout);
}
public void saveCurrentDestination(int currentDestination) {
dataStoreRepository
.saveCurrentDestination("CURRENT_DESTINATION", currentDestination);
}
// @Override
// protected void onCleared() {
// super.onCleared();
// postListMutableLiveData.setValue(null);
// finalURL.setValue(null);
// token.setValue(null);
// }
public void getPosts() {
Log.e(TAG, finalURL.getValue());
isLoading.setValue(true);
repository.remoteDataSource.getPostList(finalURL.getValue())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Response<PostList>>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull Response<PostList> postListResponse) {
if (postListResponse.isSuccessful()) {
if (postListResponse.body() != null
&& postListResponse.body().getNextPageToken() != null) {
Log.e(TAG, postListResponse.body().getNextPageToken());
token.setValue(postListResponse.body().getNextPageToken());
isLoading.setValue(false);
}
postListMutableLiveData.setValue(postListResponse.body());
for (int i = 0; i < postListResponse.body().getItems().size(); i ) {
repository.localDataSource.insertItem(postListResponse.body()
.getItems().get(i))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new CompletableObserver() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onComplete() {
}
@Override
public void onError(@NonNull Throwable e) {
}
});
}
finalURL.setValue(finalURL.getValue() "&pageToken=" token.getValue());
} else {
isLoading.setValue(false);
errorCode.setValue(postListResponse.code());
Log.e(TAG, "onNext: " postListResponse.code());
Log.e(TAG, "onNext: " postListResponse.errorBody());
}
}
@Override
public void onError(@NonNull Throwable e) {
isLoading.setValue(false);
Log.e(TAG, e.getMessage() e.getCause());
// ifAnythingWrongHappened.setValue(true);
if (e instanceof HttpException) {
errorCode.setValue(((HttpException) e).code());
}
}
@Override
public void onComplete() {
}
});
}
public void getPostListByLabel() {
isLoading.setValue(true);
Log.e(TAG, finalURL.getValue());
repository.remoteDataSource.getPostListByLabel(finalURL.getValue())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Response<com.blogspot.abtallaldigital.pojo.PostList>>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull Response<com.blogspot.abtallaldigital.pojo.PostList> postListResponse) {
if (postListResponse.isSuccessful()) {
if (postListResponse.body() != null) {
// Log.e(TAG, postListResponse.body().getNextPageToken());
token.setValue(postListResponse.body().getNextPageToken());
}
postListMutableLiveData.setValue(postListResponse.body());
isLoading.setValue(false);
finalURL.postValue(Constants.getBaseUrlPostsByLabel()
"posts?labels=" label.getValue() "&pageToken="
token.getValue()
"&key=" Constants.getKEY());
} else {
isLoading.setValue(false);
errorCode.setValue(postListResponse.code());
Log.e(TAG, "onNext: " postListResponse.code());
Log.e(TAG, "onNext: " postListResponse.errorBody());
}
}
@Override
public void onError(@NonNull Throwable e) {
isLoading.setValue(false);
Log.e(TAG, e.getMessage() e.getCause());
if (e instanceof HttpException) {
errorCode.setValue(((HttpException) e).code());
}
}
@Override
public void onComplete() {
}
});
}
public void getItemsBySearch(String keyword) {
isLoading.setValue(true);
searchError.setValue(false);
String url = Constants.getBaseUrl()
"search?q=" keyword "&key=" Constants.getKEY();
Log.e(TAG, "getItemsBySearch: " url);
repository.remoteDataSource.getPostListBySearch(url)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Response<com.blogspot.abtallaldigital.pojo.PostList>>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull Response<PostList> postListResponse) {
if (postListResponse.isSuccessful()) {
if (postListResponse.body() != null
&& postListResponse.body().getNextPageToken() != null) {
Log.e(TAG, postListResponse.body().getNextPageToken());
token.setValue(postListResponse.body().getNextPageToken());
isLoading.setValue(false);
}
postListMutableLiveData.setValue(postListResponse.body());
} else {
isLoading.setValue(false);
searchError.setValue(true);
Log.e(TAG, "onNext: list is null");
}
}
@Override
public void onError(@NonNull Throwable e) {
isLoading.setValue(false);
Log.e(TAG, e.getMessage() e.getCause());
// ifAnythingWrongHappened.setValue(true);
if (e instanceof HttpException) {
errorCode.setValue(((HttpException) e).code());
}
}
@Override
public void onComplete() {
}
});
}
public void getItemsBySearchInDB(String keyword) {
Log.d(TAG, "getItemsBySearchInDB: called");
repository.localDataSource.getItemsBySearch(keyword)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<List<com.blogspot.abtallaldigital.pojo.Item>>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull List<Item> items) {
if (items.isEmpty()) {
searchError.setValue(true);
Log.e(TAG, "onNext: list is empty");
} else {
getItemsBySearchMT.setValue(items);
Log.d(TAG, "onNext: " items.size());
}
}
@Override
public void onError(@NonNull Throwable e) {
searchError.setValue(true);
}
@Override
public void onComplete() {
}
});
}
public void insertFavorites(FavoritesEntity favoritesEntity) {
repository.localDataSource.insertFavorites(favoritesEntity)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new CompletableObserver() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onComplete() {
}
@Override
public void onError(@NonNull Throwable e) {
Log.e(TAG, "onError: " e.getMessage());
}
});
}
public LiveData<List<FavoritesEntity>> getAllFavorites() {
return repository.localDataSource.getAllFavorites();
}
public void deleteFavoritePost(FavoritesEntity favoritesEntity) {
repository.localDataSource.deleteFavorite(favoritesEntity);
}
public void deleteAllFavorites() {
repository.localDataSource.deleteAllFavorites()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new CompletableObserver() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onComplete() {
}
@Override
public void onError(@NonNull Throwable e) {
Log.e(TAG, "onError: " e.getMessage());
}
});
}
}
CodePudding user response：
Try initializing the adapter in onCreate instead of onViewCreated
Then you can set the adapter on recyclerview in onViewCreated.
Also use try using LiveData Event Wrapper : https://stackoverflow.com/a/51762972/9854554
It will prevent livedata observer from getting data again on fragment resume (when we subscribe again on the livedata)
CodePudding user response：
you are set recycler view data in onViewCreated which called everytime, i recommend viewmodel for better lifecycle handing, use LiveData or StateFlow in viewModel to prove your data integrity