为什么我在MediaStore查询android中没有遇到这样的列异常？

在我的应用程序中，我试图获得所有的艺术家。为了得到这个，我使用下面的代码

 public static List<ArtistModel> getAllArtists(Activity activity, Context context) {
    List<ArtistModel> artistList = new ArrayList<>();
    if (ContextCompat.checkSelfPermission(context, android.Manifest.permission.READ_EXTERNAL_STORAGE) !=
            PackageManager.PERMISSION_GRANTED) {

        String []permission = new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE};

        ActivityCompat.requestPermissions(activity, permission, 100);

    } else {
        ContentResolver contentResolver = context.getContentResolver();

        Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        String [] projection = {MediaStore.Audio.Artists.ARTIST,
                                MediaStore.Audio.Artists.ARTIST_KEY,
                                MediaStore.Audio.Artists.NUMBER_OF_ALBUMS,
                                MediaStore.Audio.Artists.NUMBER_OF_TRACKS,
                                MediaStore.Audio.Artists._ID,
                                MediaStore.Audio.Artists._COUNT};
        String sortOrder = MediaStore.Audio.Artists.ARTIST + " ASC";
        Cursor cursor = contentResolver.query(uri, projection, null, null, sortOrder);

        if (cursor != null && cursor.moveToFirst()) {
            int totalArtists = cursor.getCount();
            LogUtility.debugLog(SongUtility.class.getSimpleName(), "Total number of artists " + totalArtists);
            while (cursor.moveToNext()) {
                ArtistModel artistModel = new ArtistModel();
                artistModel.setArtist(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Artists.ARTIST)));
                artistModel.setArtistKey(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Artists.ARTIST_KEY)));
                artistModel.setNumberOfAlbums(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Artists.NUMBER_OF_ALBUMS)));
                artistModel.setNumberOfTracks(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Artists.NUMBER_OF_TRACKS)));
                artistModel.setArtistId(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Artists._ID)));
                artistModel.setArtistCount(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Artists._COUNT)));

                artistList.add(artistModel);
            }
        }
    }
    return artistList;
}

我浏览了Media Store类，发现MediaStore.Audio.Artists正在实现MediaStore.Audio.ArtistColumns，该接口包含以下列

   public interface ArtistColumns {
        String ARTIST = "artist";
        String ARTIST_KEY = "artist_key";
        String NUMBER_OF_ALBUMS = "number_of_albums";
        String NUMBER_OF_TRACKS = "number_of_tracks";
    }

---

我的问题是，这些专栏何时可用，为什么我没有遇到这样的专栏例外。我遗漏了什么吗？有什么帮助吗？

您正在使用此URI：

Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;

而不是：

Uri uri = MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI;

---

检查您的

projection

是否引用了

MediaStore.Audio.Artists

而不是

MediaStore.Audio.Media

也许这会有所帮助：我尝试了您的代码，但我现在面临以下异常SQLiteException:没有这样的列：\u count（代码1）：，coulmn count在BaseColumn中可用，并且class Artist正在实现base column，那么为什么会抛出该异常呢？您确定相关表中存在该列吗？它可能不存在，扩展

BaseColumn

接口并不一定意味着所有声明的列都存在。如果表中的列可用或不可用，如何检查此列？

Uri uri = MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI;