小编Him*_*rma的帖子

我试图使用自定义适配器访问列表活动.我已经直接尝试了它而没有使用任何自定义适配器它工作正常,但因为我想在列表视图中添加更多功能我想实现自定义适配器.现在我有试过但我得到一个没有数据可见的空列表视图.列表 - 活动

public class MainActivity extends ListActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";

         String[] projection = {
                    MediaStore.Audio.Media._ID,
                    MediaStore.Audio.Media.ARTIST,
                    MediaStore.Audio.Media.TITLE,
                    MediaStore.Audio.Media.DATA,
                    MediaStore.Audio.Media.DISPLAY_NAME,
                    MediaStore.Audio.Media.DURATION,

            };
            //query 

            musiccursor = this.managedQuery(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,projection,selection,null,sortOrder);
            music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA);


            int a[]= new int[]{R.id.TitleSong,R.id.Artist};


            Custom_Adapter adapter = new Custom_Adapter(this,R.layout.music_items, musiccursor, new String[]{MediaStore.Audio.Media.TITLE,MediaStore.Audio.Media.ARTIST} ,a);

            this.setAdapter(adapter);

            }
    }

定制适配器

    public class Custom_Adapter extends SimpleCursorAdapter {


    private Context mContext;
    private Context appContext;
    private int layout;
    private Cursor cr;
    private final …