java - 在android中查找存储中的所有mp3文件

我试图找到所有mp3文件，但不知道，我找到了这段代码，唯一的问题是未声明getActivity（），我不知道如何解决，请帮帮我。如果有更好的方法，我接受建议。

这是我的课：

 public class SongsManager {
    private ArrayList<Song> songsList;
    public void getMp3Songs() {
        Uri allSongsUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
        Cursor cursor =  getActivity().getContentResolver().query(allSongsUri, null, null, null, selection);
        if (cursor != null) {
            if (cursor.moveToFirst()) {
                do {
                    Song song = new Song(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media._ID)),
                                         cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME)),
                                         cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST)),
                                         cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA)));
                    songsList.add(song);
//                    album_name = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM));
//                    int album_id = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
//                    int artist_id = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST_ID));
                } while (cursor.moveToNext());
            }
            cursor.close();
        }
    }
}

最佳答案

将方法（getMp3Songs）的参数设置为上下文：

public class SongsManager {
private ArrayList<Song> songsList;
public void getMp3Songs(Context ctx) {
    Uri allSongsUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
    Cursor cursor =  ctx.getContentResolver().query(allSongsUri, null, null, null, selection);
    if (cursor != null) {
        if (cursor.moveToFirst()) {
            do {
                Song song = new Song(cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media._ID)),
                                     cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME)),
                                     cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST)),
                                     cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA)));
                songsList.add(song);
//                    album_name = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM));
//                    int album_id = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
//                    int artist_id = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST_ID));
            } while (cursor.moveToNext());
        }
        cursor.close();
    }
}

}