我的MoviesApp遇到问题已有一段时间了，我觉得我已经用尽了所有的知识；我对Android很陌生，所以请耐心:-)
MoviesApp是一个简单的电影列表应用程序，用户可以在其中滚动浏览电影列表，查看每个电影的详细信息并将其收藏夹保存在SQLite数据库中。 我使用SharedPreference对影片的受欢迎程度，评分和收藏夹（数据库中保存的唯一列表）进行排序，但是当我对每个影片进行更改时，UI根本不会更新。
我真的很困，老实说，我可以用另一双眼睛做，因为即使答案盯着我，我也看不到
我将链接粘贴到下面的项目：
https://drive.google.com/file/d/1SweLpwfo5RntXrbtLPP3N_xS1bVs32Ze/view?usp=sharing
谢谢！
更新：我相信问题将在MainActivity类中，在该类中声明了RecyclerView Loader-特别是在onLoadFinished（）中。
@SuppressWarnings({"WeakerAccess", "unused", "CanBeFinal"})
public class MainActivity extends AppCompatActivity implements
LoaderManager.LoaderCallbacks,
MovieAdapter.MovieDetailClickHandler, SwipeRefreshLayout.OnRefreshListener {
private static final String TAG = MainActivity.class.getSimpleName();
public static final String MOVIE_ID = "movieId";
private final static String LIFECYCLE_CALLBACKS_LAYOUT_MANAGER_KEY = "KeyForLayoutManagerState";
Parcelable savedLayoutManagerState;
public RecyclerView movieListRV;
private GridLayoutManager gridLayoutManager =
new GridLayoutManager(this, 1);
Context context = this;
// Loader IDs for loading the main API and the poster API, respectively
private static final int ID_LOADER_LIST_MOVIES = 1;
private static final int ID_LOADER_CURSOR = 2;
// adapter
private MovieAdapter adapter;
// detect internet connection
NetworkDetection networkDetection;
// swipe to refresh
SwipeRefreshLayout swipeRefreshLayout;
// sortOption
String sortOption = null;
// movie projection
private final String[] projection = new String[]{
MoviesContract.MovieEntry.COLUMN_MOVIE_POSTER,
MoviesContract.MovieEntry.COLUMN_MOVIE_ID
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Stetho.initializeWithDefaults(this);
Toolbar toolbar = findViewById(R.id.settings_activity_toolbar);
setSupportActionBar(toolbar);
toolbar.setTitleTextColor(Color.WHITE);
networkDetection = new NetworkDetection(this);
swipeRefreshLayout = findViewById(R.id.discover_swipe_refresh);
swipeRefreshLayout.setOnRefreshListener(MainActivity.this);
swipeRefreshLayout.setColorScheme(android.R.color.holo_red_dark);
movieListRV = findViewById(R.id.recycler_view_movies);
movieListRV.setLayoutManager(gridLayoutManager);
movieListRV.setHasFixedSize(true);
ViewTreeObserver viewTreeObserver = movieListRV.getViewTreeObserver();
viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
calculateSize();
}
});
adapter = new MovieAdapter(this, this);
movieListRV.setAdapter(adapter);
RecyclerViewItemDecorator itemDecorator = new RecyclerViewItemDecorator(context,
R.dimen.item_offset);
movieListRV.addItemDecoration(itemDecorator);
final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences
(context);
SharedPreferences.OnSharedPreferenceChangeListener preferenceChangeListener = new
SharedPreferences.OnSharedPreferenceChangeListener() {
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
adapter.deleteItemsInList();
onRefresh();
if (key.equals(getString(R.string.pref_sort_by_key))) {
initializeloader();
}
}
};
preferences.registerOnSharedPreferenceChangeListener(preferenceChangeListener);
initializeloader();
}
private static final int sColumnWidth = 200;
private void calculateSize() {
int spanCount = (int) Math.floor(movieListRV.getWidth() / convertDPToPixels(sColumnWidth));
((GridLayoutManager) movieListRV.getLayoutManager()).setSpanCount(spanCount);
}
@SuppressWarnings("SameParameterValue")
private float convertDPToPixels(int dp) {
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
float logicalDensity = metrics.density;
return dp * logicalDensity;
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelable(LIFECYCLE_CALLBACKS_LAYOUT_MANAGER_KEY, gridLayoutManager
.onSaveInstanceState());
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
if (savedInstanceState != null) {
savedLayoutManagerState = savedInstanceState.getParcelable
(LIFECYCLE_CALLBACKS_LAYOUT_MANAGER_KEY);
movieListRV.getLayoutManager().onRestoreInstanceState(savedLayoutManagerState);
}
}
@Override
public Loader onCreateLoader(int id, Bundle args) {
adapter.deleteItemsInList();
String urlMovieActivity;
switch (id) {
case ID_LOADER_CURSOR:
return new CursorLoader(context, MoviesContract.MovieEntry.MOVIES_CONTENT_URI,
projection, null, null, null);
case ID_LOADER_LIST_MOVIES:
urlMovieActivity = NetworkUtils.buildUrlMovieActivity(context, sortOption);
return new MovieLoader(this, urlMovieActivity);
default:
return null;
}
}
@Override
public void onLoadFinished(Loader loader, Object data) {
adapter.deleteItemsInList();
TextView noMoviesMessage = findViewById(R.id.no_movies_found_tv);
switch (loader.getId()) {
case ID_LOADER_CURSOR:
adapter.InsertList(data);
break;
case ID_LOADER_LIST_MOVIES:
//noinspection unchecked
List<MovieItem> movieItems = (List<MovieItem>) data;
if (networkDetection.isConnected()) {
noMoviesMessage.setVisibility(View.GONE);
adapter.InsertList(movieItems);
movieListRV.getLayoutManager().onRestoreInstanceState(savedLayoutManagerState);
} else {
noMoviesMessage.setVisibility(View.VISIBLE);
}
break;
}
adapter.notifyDataSetChanged();
}
@Override
public void onLoaderReset(Loader loader) {
switch (loader.getId()) {
case ID_LOADER_CURSOR:
adapter.InsertList(null);
break;
case ID_LOADER_LIST_MOVIES:
adapter.InsertList(null);
break;
}
}
@Override
public void onPostResume(Loader loader) {
super.onPostResume();
getLoaderManager().initLoader(ID_LOADER_CURSOR, null, this);
}
@Override
public void onSelectedItem(int movieId) {
Intent goToDetailActivity = new Intent(this, DetailMovieActivity.class);
goToDetailActivity.putExtra(MOVIE_ID, movieId);
startActivity(goToDetailActivity);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_general, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
int id = menuItem.getItemId();
if (id == R.id.action_general_settings) {
Intent goToSetting = new Intent(this, SettingsActivity.class);
startActivity(goToSetting);
return true;
} else if (id == R.id.action_refresh) {
onRefresh();
}
return super.onOptionsItemSelected(menuItem);
}
/**
* Called when a swipe gesture triggers a refresh.
*/
@Override
public void onRefresh() {
adapter.deleteItemsInList();
swipeRefreshLayout.setRefreshing(false);
restartloader();
adapter.notifyDataSetChanged();
}
private void restartloader() {
adapter.deleteItemsInList();
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_favourite))) {
getLoaderManager().restartLoader(ID_LOADER_CURSOR, null, MainActivity
.this);
}
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_popularity))) {
sortOption = NetworkUtils.MOST_POPULAR_PARAM;
getLoaderManager().restartLoader(ID_LOADER_LIST_MOVIES, null,
MainActivity.this);
}
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_rating))) {
sortOption = NetworkUtils.TOP_RATED_PARAM;
getLoaderManager().restartLoader(ID_LOADER_LIST_MOVIES, null,
MainActivity.this);
}
adapter.notifyDataSetChanged();
}
public void initializeloader() {
restartloader();
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_favourite))) {
getLoaderManager().initLoader(ID_LOADER_CURSOR, null, MainActivity
.this);
}
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_popularity))) {
onRefresh();
sortOption = NetworkUtils.MOST_POPULAR_PARAM;
getLoaderManager().initLoader(ID_LOADER_LIST_MOVIES, null,
MainActivity.this);
}
if (MoviePreferences.getSortByPreference(context).equals(getString(R.string
.pref_sort_by_rating))) {
onRefresh();
sortOption = NetworkUtils.TOP_RATED_PARAM;
getLoaderManager().initLoader(ID_LOADER_LIST_MOVIES, null,
MainActivity.this);
}
adapter.notifyDataSetChanged();
}
}