RecyclerView不会在片段内进行权限检查后的首次启动时加载数据 [英] RecyclerView doesn't load data on first launch after Permission Check inside fragment
问题描述
在进行权限检查之后，RecyclerView适配器在第一次启动时不会加载数据.我必须重新点击标签才能获取数据.
RecyclerView adapter doesn't load data on first launch after Permission check. I have to re-tap the tab to get the data.
我已经访问/尝试了这些链接-
I have already visited/tried these links -
- RecyclerView在首次启动时不会加载数据使用FirebaseRecyclerAdapter
但是什么都没有. 试图设置全局适配器，所以我可以从 onResume()调用 notifyDataSetChanged().仍然没有用.
But nothing works yet. Tried to set global adapter, So I can call notifyDataSetChanged() from onResume(). Still It didn't worked.
这里的代码-
onCreateView()-
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_third, container, false);
recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
if (checkAndRequestPermissions()) {
loadSongList();
}
return view;
}
onRequestPermissionResult-
loadSongList(); // method
loadSongList()-
private void loadSongList() {
loadAudio();
initRecyclerView();
}
loadAudio()-
loadAudio() // accessing data from content resolver
initRecyclerView()-
private void initRecyclerView() {
if (mAudioList != null && mAudioList.size() > 0) {
AudioAdapter adapter = new AudioAdapter(mAudioList, getActivity());
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
DIviderItemDecoration dividerItemDecoration = new DIviderItemDecoration(getContext(), linearLayoutManager.getOrientation());
recyclerView.addItemDecoration(dividerItemDecoration);
recyclerView.setAdapter(adapter);
RecyclerViewItemClick.addTo(recyclerView).setOnItemClickListener(new RecyclerViewItemClick.OnItemClickListener() {
@Override
public void onItemClicked(RecyclerView recyclerView, int position, View v) {
// life sucks
}
});
}
}
loadAudio()-
private void loadAudio() {
ContentResolver contentResolver = getActivity().getContentResolver();
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
String selection = MediaStore.Audio.Media.IS_MUSIC + "!= 0";
String sortOrder = MediaStore.Audio.Media.TITLE + " ASC";
Cursor cursor = contentResolver.query(uri, null, selection, null, sortOrder);
if (cursor != null && cursor.getCount() > 0) {
mAudioList = new ArrayList<>();
while (cursor.moveToNext()) {
String data = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA));
String title = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE));
String album = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM));
String artist = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));
Long albumId = cursor.getLong(cursor
.getColumnIndexOrThrow(MediaStore.Audio.Media._ID));
Long artWorkId = cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.ALBUM_ID));
int duration = cursor.getInt(cursor
.getColumnIndexOrThrow(MediaStore.Audio.Media.DURATION));
Uri sArtworkUri = Uri
.parse("content://media/external/audio/albumart");
Uri albumArtUri = ContentUris.withAppendedId(sArtworkUri, artWorkId);
// Save to audioList
mAudioList.add(new Audio(albumId, data, title, album, artist, albumArtUri, duration));
}
}
if (cursor != null) {
cursor.close();
}
}
AudioAdapter-
public class AudioAdapter extends RecyclerView.Adapter<AudioAdapter.CustomViewHolder> {
List<Audio> mList = Collections.emptyList();
Context mContext;
public AudioAdapter(List<Audio> list, Context context) {
mList = list;
mContext = context;
}
@Override
public CustomViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.custom_row, parent, false);
return new CustomViewHolder(v);
}
@Override
public void onBindViewHolder(CustomViewHolder holder, int position) {
Audio audio = mList.get(position);
holder.title.setText(audio.getTitle());
holder.description.setText(audio.getArtist());
Glide.with(mContext).load(audio.imageId).asBitmap()
.centerCrop()
.diskCacheStrategy(DiskCacheStrategy.RESULT)
.skipMemoryCache(true)
.placeholder(R.drawable.headset_2)
.into(holder.imageView);
}
@Override
public int getItemCount() {
return mList.size();
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
public void insert(int position, Audio list) {
mList.add(position, list);
notifyItemChanged(position);
}
public void remove(Audio list) {
int position = mList.indexOf(list);
mList.remove(position);
notifyItemRemoved(position);
}
static class CustomViewHolder extends RecyclerView.ViewHolder {
CardView cv;
TextView title;
TextView description;
ImageView imageView;
public CustomViewHolder(View itemView) {
super(itemView);
cv = (CardView) itemView.findViewById(R.id.cardView);
title = (TextView) itemView.findViewById(R.id.playList_name);
description = (TextView) itemView.findViewById(R.id.album_artist);
imageView = (ImageView) itemView.findViewById(R.id.imageView1);
}
}}
UDPATE: checkAndRequestPermission-
private boolean checkAndRequestPermissions() {
if (SDK_INT >= Build.VERSION_CODES.M) {
int permissionReadPhoneState = ContextCompat.checkSelfPermission(getContext(), (Manifest.permission.READ_PHONE_STATE));
int permissionStorage = ContextCompat.checkSelfPermission(getContext(), Manifest.permission.READ_EXTERNAL_STORAGE);
List<String> listPermissionsNeeded = new ArrayList<>();
if (permissionReadPhoneState != PackageManager.PERMISSION_GRANTED) {
listPermissionsNeeded.add(Manifest.permission.READ_PHONE_STATE);
}
if (permissionStorage != PackageManager.PERMISSION_GRANTED) {
listPermissionsNeeded.add(Manifest.permission.READ_EXTERNAL_STORAGE);
}
if (!listPermissionsNeeded.isEmpty()) {
requestPermissions(listPermissionsNeeded.toArray(new String[listPermissionsNeeded.size()]), REQUEST_ID_MULTIPLE_PERMISSIONS);
return false;
} else {
return true;
}
}
return false;
}
在删除ActivityCompat并仅调用requestPermission之后，该片段正在接收回调，但是现在我遇到了错误.下面的logcat-
After removing ActivityCompat and just calling requestPermission, the fragment is receiving callback, But now I'm getting error. logcat below -
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.ArrayList.get(int)' on a null object reference
at com.example.ansh.sharedpreferencessimple.service.MusicService.playSong(MusicService.java:167)
at com.example.ansh.sharedpreferencessimple.ThirdFragment$2.onItemClicked(ThirdFragment.java:196)
at com.example.ansh.sharedpreferencessimple.helper.RecyclerViewItemClick$1.onClick(RecyclerViewItemClick.java:21)
at android.view.View.performClick(View.java:6205)
at android.view.View$PerformClick.run(View.java:23653)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
谢谢您的任何帮助.
推荐答案
这是您问题的答案.
您的loadAudio()方法填充您的mAudioList(即您的数组列表)或列出任何内容.
Your loadAudio() method fill up your mAudioList which is your arraylist or list whatever it was.
所以，主要问题是，当您先调用loadAudio()然后在initRecyclerView()中调用initRecyclerView()时，mAudioList仍然为null，因为那时您的mAudioList尚未填充到loadAudio()中.
So, main problem is that when you call loadAudio() and then initRecyclerView() inside your initRecyclerView() the mAudioList is still null because at that time your mAudioList is not fill up inside your loadAudio().
所以，您的答案是在loadAudio()函数末尾调用initRecyclerView()，这将解决您的问题.
So, the problem of your answer is to call initRecyclerView() at the end of loadAudio() function and this will resolve your issue.
例如
private void loadAudio()
{
// Get your arraylist of audio and all the stuff
if (cursor != null)
{
cursor.close();
}
// Call init function here.
initRecyclerView();
}
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