我是这个Android世界的新人。我目前正在开发Android项目，即音乐播放器，但由于我的回收站视图没有显示任何应该是歌曲列表的内容，所以我在某一时刻停了下来。 我甚至检查了我的logcat，但无法弄清楚数据是否有约束力。任何一种帮助都会感激不尽。
SongListAdapter.java
public class SongListAdapter extends RecyclerView.Adapter<SongListAdapter.MyViewHolder> {
ArrayList<SongDetailsJDO> mSongDetailsJDOs;
LayoutInflater mLayoutInflater;
Context mContext;
private static final String TAG = "SongListAdapter";
private boolean mIsSongPlaying = false;
private String mCurrentSongId = "-1";
public SongListAdapter(Context context, ArrayList<SongDetailsJDO> pSongDetailsJDOs) {
mContext = context;
mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mSongDetailsJDOs = pSongDetailsJDOs;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View lView = mLayoutInflater.inflate(R.layout.recycler_view_item, parent, false);
return new MyViewHolder(lView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
Uri lUri = null;
if (mSongDetailsJDOs.get(position).getAlbumId() != null && !mSongDetailsJDOs.get(position).getAlbumId().equals("")) {
lUri = ContentUris.withAppendedId(Uri.parse("content://media/external/audio/albumart"), Long.parseLong(mSongDetailsJDOs.get(position).getAlbumId()));
Picasso.with(mContext).load(lUri).resize(100, 100).placeholder(R.drawable.placeholder).into(holder.albumImageIV);
} else
holder.albumImageIV.setImageResource(R.drawable.placeholder);
String lTrackName = mSongDetailsJDOs.get(position).getTitle();
if (lTrackName != null)
holder.trackNameTV.setText(lTrackName.trim());
else
holder.trackNameTV.setText("<Unknown>");
String lAlbumName = mSongDetailsJDOs.get(position).getAlbumName();
if (lAlbumName != null)
holder.albumAndArtistDetailsTV.setText(lAlbumName.trim());
else
holder.albumAndArtistDetailsTV.setText("<Unknown>");
if (mSongDetailsJDOs.get(position).getFavouriteStatus() == 1)
holder.favouriteIV.setImageResource(R.drawable.fav);
else
holder.favouriteIV.setImageResource(R.drawable.fav_u);
// TODO: @holder.animationDrawable use it change Visibility and start (Animation)
if (mIsSongPlaying && mSongDetailsJDOs.get(position).getSongId().equals(mCurrentSongId)) {
holder.eqIv.setVisibility(View.VISIBLE);
holder.animationDrawable = (AnimationDrawable) holder.eqIv.getBackground();
holder.animationDrawable.start();
} else {
holder.eqIv.setVisibility(View.INVISIBLE);
}
}
@Override
public int getItemCount() {
if (mSongDetailsJDOs != null)
return mSongDetailsJDOs.size();
else
return 0;
}
/**
* Called when data is being updated in DB
*/
public void favChanged(int pPosition, int pFavStatus) {
mSongDetailsJDOs.get(pPosition).setFavouriteStatus(pFavStatus);
notifyItemChanged(pPosition);
}
/**
* View Holder class for Rec view
*/
class MyViewHolder extends RecyclerView.ViewHolder {
ImageView albumImageIV;
TextView trackNameTV;
TextView albumAndArtistDetailsTV;
ImageView favouriteIV;
ImageView eqIv;
AnimationDrawable animationDrawable;
MyViewHolder(View itemView) {
super(itemView);
albumImageIV = (ImageView) itemView.findViewById(R.id.album_artwork_iv);
trackNameTV = (TextView) itemView.findViewById(R.id.title_name_tv);
albumAndArtistDetailsTV = (TextView) itemView.findViewById(R.id.artist_author_name_tv);
favouriteIV = (ImageView) itemView.findViewById(R.id.fav_iv);
eqIv = (ImageView) itemView.findViewById(R.id.eq_iv);
}
}
/**
* Swap the data with the new JDO list
*
* @param pSongDetailsJDOs
*/
public void swapData(ArrayList<SongDetailsJDO> pSongDetailsJDOs) {
mSongDetailsJDOs = pSongDetailsJDOs;
notifyDataSetChanged();
}
/**
* Returns the list of currently loaded JDO's
* @return
*/
public List<SongDetailsJDO> getData() {
return mSongDetailsJDOs;
}
/**
* Gets the @{@link SongDetailsJDO} object at the specified position
* @param pPosition
* @return the {@link SongDetailsJDO} object
*/
public SongDetailsJDO getItemAtPosition(int pPosition) {
return mSongDetailsJDOs.get(pPosition);
}
/**
* Update Song Play status
* @param pStatus the status weather is playing or not
* @param lSongId the song id the playing song
*/
public void updateSongPlayStatus(boolean pStatus, String lSongId) {
mIsSongPlaying = pStatus;
mCurrentSongId = lSongId;
notifyDataSetChanged();
}
}
SongListActivity.java
public class SongsListActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor>, SharedPreferences.OnSharedPreferenceChangeListener {
private RecyclerView mRecyclerView;
private SongListAdapter mAdapter;
private ArrayList<SongDetailsJDO> mSongDetailsJDOs;
private TextView mNoSongTV;
private static final int LOADER_ID = 101;
private int REQUEST_CODE = 102;
private static final String TAG = "SongsListActivity";
private SharedPreferences mSharedPreferences;
private SharedPreferences.Editor mPrefEditor;
private SharedPreferences.OnSharedPreferenceChangeListener mOnSharedPreferenceChangeListener;
private FirebaseAnalytics mFirebaseAnalytics;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.rec_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(SongsListActivity.this));
mNoSongTV = (TextView) findViewById(R.id.no_song_tv);
mSongDetailsJDOs = new ArrayList<>();
mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
mPrefEditor = mSharedPreferences.edit();
mSharedPreferences.registerOnSharedPreferenceChangeListener(this);
FirebaseApp.initializeApp(this);
mFirebaseAnalytics = FirebaseAnalytics.getInstance(this);
loadData();
}
private void loadData() {
FirebaseCrash.report(new Exception("OMG An Exception"));
boolean lIsAppLoadingFirstTime = mSharedPreferences.getBoolean(getString(R.string.is_app_loading_first_time), true);
if (lIsAppLoadingFirstTime) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 0);
} else {
mPrefEditor.putBoolean(getString(R.string.is_app_loading_first_time), false);
mPrefEditor.apply();
new LoadDataToDbBackground().execute();
// TODO: Create Loader here
}
} else {
loadDataToRecyclerView();
if (mSharedPreferences.getBoolean(getString(R.string.is_song_playing), false)) {
// TODO: Create Loader here
SongDetailsJDO lJDO = getSongJDO(mSharedPreferences.getString(getString(R.string.song_id), ""));
startActivityForResult(new Intent(SongsListActivity.this, PlayerActivity.class)
.putExtra(getString(R.string.song_jdo), lJDO), REQUEST_CODE);
}
}
}
private class LoadDataToDbBackground extends AsyncTask<Void, Integer, Void> {
ProgressDialog mProgressDialog;
@Override
protected void onPreExecute() {
mProgressDialog = new ProgressDialog(SongsListActivity.this);
mProgressDialog.setMessage("Please Wait");
mProgressDialog.setTitle("Loading");
mProgressDialog.show();
super.onPreExecute();
}
@Override
protected void onPostExecute(Void aVoid) {
mProgressDialog.dismiss();
super.onPostExecute(aVoid);
}
@Override
protected Void doInBackground(Void... params) {
CommonHelper lHelper = new CommonHelper();
lHelper.loadSongToDB(SongsListActivity.this);
runOnUiThread(new Runnable() {
@Override
public void run() {
loadDataToRecyclerView();
}
});
return null;
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 0) {
boolean lGranted = true;
for (int lResult : grantResults) {
if (lResult == PackageManager.PERMISSION_DENIED)
lGranted = false;
}
if (lGranted)
loadData();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CODE) {
if (data != null && data.getExtras() != null && resultCode == PlayerActivity.RESULT_CODE) {
//if data changed reload the recyclerView
if (data.getBooleanExtra(getString(R.string.is_data_changed), false)) {
mSongDetailsJDOs = new SongDetailTable(this).getAllSongs();
mAdapter.swapData(mSongDetailsJDOs);
}
}
}
// updateCurrentSongIndication();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater lMenuInflater = getMenuInflater();
lMenuInflater.inflate(R.menu.menu_song_list, menu);
SearchManager lSearchManager = (SearchManager) getSystemService(SEARCH_SERVICE);
SearchView lSearchView = (SearchView) menu.findItem(R.id.action_search).getActionView();
lSearchView.setSearchableInfo(lSearchManager.getSearchableInfo(getComponentName()));
lSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
filterRecView(newText);
return true;
}
});
return true;
}
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new CursorLoader(this, MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, MediaStore.Audio.Media.TITLE + " ASC");
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
ArrayList<SongDetailsJDO> lSongDetailsNew = new ArrayList<>();
if (data.moveToFirst()) {
do {
lSongDetailsNew.add(new SongDetailsJDO(data.getString(data.getColumnIndex(MediaStore.Audio.Media.TITLE)),
data.getString(data.getColumnIndex(MediaStore.Audio.Media.ALBUM)),
data.getString(data.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID)),
data.getString(data.getColumnIndex(MediaStore.Audio.Media._ID)),
data.getInt(data.getColumnIndex(MediaStore.Audio.Media.DURATION)), 0));
} while (data.moveToNext());
}
compareDataAndMakeChangesToDB(lSongDetailsNew);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
}
@Override
protected void onResume() {
super.onResume();
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
Log.d(TAG, "onWindowFocusChanged: ");
updateCurrentSongIndication();
}
private void updateCurrentSongIndication() {
if (mSharedPreferences.getBoolean(getString(R.string.is_song_playing), false)) {
mAdapter.updateSongPlayStatus(true, mSharedPreferences.getString(getString(R.string.song_id), ""));
mRecyclerView.smoothScrollToPosition(getPositionOfSongId(mSharedPreferences.getString(getString(R.string.song_id), "")));
} else {
if(mAdapter!=null)
mAdapter.updateSongPlayStatus(false, "-1");
}
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
updateCurrentSongIndication();
}
private void compareDataAndMakeChangesToDB(ArrayList<SongDetailsJDO> pSongDetailsNew) {
Log.d(TAG, "compareDataAndMakeChangesToDB: Called ============");
ArrayList<String> lSongIdsToBeDeleted = new ArrayList<>();
for (SongDetailsJDO lSongDetailsJDO : mSongDetailsJDOs) {
lSongIdsToBeDeleted.add(lSongDetailsJDO.getSongId());
}
ArrayList<SongDetailsJDO> lNewSongsToBeAdded = new ArrayList<>();
for (SongDetailsJDO lSongDetailsJDO : pSongDetailsNew) {
if (lSongIdsToBeDeleted.contains(lSongDetailsJDO.getSongId())) {
lSongIdsToBeDeleted.remove(lSongDetailsJDO.getSongId());
} else
lNewSongsToBeAdded.add(lSongDetailsJDO);
}
if (lSongIdsToBeDeleted.size() > 0 || lNewSongsToBeAdded.size() > 0) {
SongDetailTable lSongDetailTable = new SongDetailTable(this);
lSongDetailTable.removeSongsForIds(lSongIdsToBeDeleted);
lSongDetailTable.insertSongs(lNewSongsToBeAdded);
loadDataToRecyclerView();
//
// SongPlayerService lSongPlayerService = SongPlayerService.getRunningInstance();
// if (lSongPlayerService != null)
// lSongPlayerService.dataChanged();
}
}
public void onFavClick(View pView) {
//Firebase Logging
Bundle lBundle = new Bundle();
lBundle.putString(FirebaseAnalytics.Param.ITEM_CATEGORY,"Favourite Clicked");
mFirebaseAnalytics.logEvent(FirebaseAnalytics.Event.VIEW_ITEM,lBundle);
int lPosition = mRecyclerView.getChildLayoutPosition((View) pView.getParent());
SongDetailsJDO lSongDetailsJDO = mAdapter.getItemAtPosition(lPosition);
String lSongId = lSongDetailsJDO.getSongId();
SongDetailTable lSongDetailTable = new SongDetailTable(this);
int lNewFavStatus = lSongDetailsJDO.getFavouriteStatus() == 0 ? 1 : 0;
lSongDetailTable.setFavouriteStatus(lSongId, lNewFavStatus);
mAdapter.favChanged(lPosition, lNewFavStatus);
SongPlayerService mSongPlayerService = SongPlayerService.getRunningInstance();
if (mSongPlayerService != null)
mSongPlayerService.favChanged(lPosition, lNewFavStatus);
}
public void onRowClick(View pView) {
int lPosition = mRecyclerView.getChildLayoutPosition(pView);
SongDetailsJDO lJDO = mAdapter.getItemAtPosition(lPosition);
startActivityForResult(new Intent(SongsListActivity.this, PlayerActivity.class)
.putExtra(getString(R.string.song_jdo), lJDO), REQUEST_CODE);
overridePendingTransition(R.anim.from_right, R.anim.scale_down);
}
private SongDetailsJDO getSongJDO(String pSongId) {
SongDetailsJDO lJDO = null;
for (SongDetailsJDO lSongDetailsJDO : mSongDetailsJDOs) {
if (lSongDetailsJDO.getSongId().equals(pSongId)) {
lJDO = lSongDetailsJDO;
break;
}
}
return lJDO;
}
private void filterRecView(String pText) {
if (pText != null) {
if (pText.equals("")) {
mAdapter.swapData(mSongDetailsJDOs);
toggleVisibilityForNoResult(mSongDetailsJDOs.size(), pText);
} else {
ArrayList<SongDetailsJDO> lSongDetailsJDOs = new ArrayList<>();
pText = pText.toLowerCase();
for (SongDetailsJDO lDetailsJDO : mSongDetailsJDOs) {
if (lDetailsJDO.getTitle().toLowerCase().contains(pText) || lDetailsJDO.getAlbumName() != null && lDetailsJDO.getAlbumName().toLowerCase().contains(pText))
lSongDetailsJDOs.add(lDetailsJDO);
}
toggleVisibilityForNoResult(lSongDetailsJDOs.size(), pText);
mAdapter.swapData(lSongDetailsJDOs);
}
}
}
public void toggleVisibilityForNoResult(int pNumberOfSongs, String query) {
if (pNumberOfSongs == 0) {
mNoSongTV.setVisibility(View.VISIBLE);
mNoSongTV.setText(getString(R.string.nosong) + " " + query);
} else
mNoSongTV.setVisibility(View.INVISIBLE);
}
public void loadDataToRecyclerView() {
//Loading data to RecyclerView
mSongDetailsJDOs = new SongDetailTable(this).getAllSongs();
mAdapter = new SongListAdapter(SongsListActivity.this, mSongDetailsJDOs);
mRecyclerView.setAdapter(mAdapter);
}
public int getPositionOfSongId(String pSongId) {
int lPostion = -1;
for (int i = 0; i < mSongDetailsJDOs.size(); i++) {
if (mSongDetailsJDOs.get(i).getSongId().equals(pSongId)) {
lPostion = i;
break;
}
}
return lPostion;
}
}
答案 0 :(得分：0)
查看您的问题，无法确定问题的确切原因。 但我仍然会对问题提出一些暗示。
检查你的代码 mSongDetailsJDOs.size（）;什么是列表的大小，它应该是＆gt; 0.如果没有，请在活动中查看您如何通过列表。
@Override
public int getItemCount() {
if (mSongDetailsJDOs != null)
return mSongDetailsJDOs.size();
else
return 0;
}
如果以上列表是＆gt; 0然后在onBindViewHolder（）中检查它是否逐个获取位置并尝试一次渲染一个项目。
如果上述内容适合您，请告诉我。