我正在尝试获取播放列表的列表以及在安装了 Android 10 的设备上每个播放列表中有多少个大头钉。我正在使用 compileSdkVersion = targetSdkVersion = 30。我正在请求 READ_EXTERNAL_STORAGE，这似乎是必要的。

我以前从未尝试过，但这似乎很简单：获取播放列表的光标并使用该播放列表的 _id，然后将光标置于曲目上。

就获取名称和数据（位置）而言，它按预期工作，但它始终为 _id 返回 1，并且找不到任何轨道（即 cursor.getcount() 为零）。文件不为空。我可能有一个愚蠢的错误，但我没有看到。

2021 年 7 月 22 日添加：只有 5 个列名返回 *：date_modified、_id、name、_data、date_ added。除了 _id 之外的所有值都是正确的（或至少是合理的）。 _id (MediaStore.Audio.Playlists._ID) 始终为 1。

这是代码：

private void showPlaylists() {
    StringBuilder sb = new StringBuilder();
    sb.append("\nPlaylists\n");
    Uri collection;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
        collection = MediaStore.Audio.Playlists.getcontenturi(MediaStore.VOLUME_EXTERNAL);
    } else {
        collection = MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI;
    }
    String name,data;
    long id;
    // External
    try (Cursor playListCursor =
                 this.getcontentResolver().query(
                         collection,null,null)) {
        if (playListCursor == null) {
            sb.append("Cannot access external playlists\n");
            return;
        }
        for (int i = 0; i < playListCursor.getcount(); i++) {
            playListCursor.moveToPosition(i);
            name = playListCursor.getString(
                    playListCursor.getcolumnIndex("name"));
            sb.append(i).append(" ").append(name).append("\n");
            // This is apparently the path
            data = playListCursor.getString(
                    playListCursor.getcolumnIndex(MediaStore.Audio.Media.DATA));
            sb.append("    ").append(data).append("\n");
            id = playListCursor.getcolumnIndex(MediaStore.Audio.Playlists._ID);
            sb.append("    id=").append(id).append("\n");

            // Get the playlist from the id
            String[] projection = null; // All columns
            try (Cursor cursor =
                         this.getcontentResolver().query(MediaStore
                                         .Audio.Playlists.Members.getcontenturi
                                                 ("external",id),projection,null)) {
                if (cursor == null) {
                    sb.append("    Cannot get contents\n");
                } else {
                    sb.append("    Tracks: ").append(cursor.getcount())
                            .append("\n");
                }
            } catch (Exception ex) {
                String msg = "    Error getting playlist " + i;
                Log.e(TAG,msg,ex);
            }
        }
    } catch (Exception ex) {
        String msg = "Error getting external playlists";
        Utils.excMsg(this,ex);
        Log.e(TAG,ex);
    }
    Log.e(TAG,sb.toString());
}

这是Logcat中的输出：

0 Carmen Cavallero
    /storage/3535-6434/Playlists/Carmen Cavallero.m3u
    id=1
    Tracks: 0
1 Chris Botti
    /storage/3535-6434/Playlists/Chris Botti.m3u
    id=1
    Tracks: 0
2 Diana Krall
    /storage/3535-6434/Playlists/Diana Krall.m3u
    id=1
    Tracks: 0
3 Dinner Party
    /storage/3535-6434/Playlists/Dinner Party.m3u
    id=1
    Tracks: 0
4 Meditation 1
    /storage/3535-6434/Playlists/Meditation 1.m3u
    id=1
    Tracks: 0
5 Romance
    /storage/3535-6434/Playlists/Romance.m3u
    id=1
    Tracks: 0
6 Tablet
    /storage/3535-6434/Playlists/Tablet.m3u
    id=1
    Tracks: 0
7 Jean Sidwell
    /storage/3535-6434/Playlists/Jean Sidwell.m3u
    id=1
    Tracks: 0
8 Bill Evans MM2
    /storage/3535-6434/Playlists/Bill Evans MM2.m3u
    id=1
    Tracks: 0
9 Selena
    /storage/3535-6434/Playlists/Selena.m3u
    id=1
    Tracks: 0