我想列出目錄中的所有圖像以制作畫廊。下面的示例使用 Intent 獲取目錄路徑。我已經(jīng)嘗試過該listFiles()方法，但它返回 null。protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //Permision Request    ActivityCompat.requestPermissions(MainActivity.this,            new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},            1);    initialize();}//For the Intent to get Folderprivate void initialize() {    Intent i = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);    i.addCategory(Intent.CATEGORY_DEFAULT);    startActivityForResult(Intent.createChooser(i, "Choose directory"), 9999);}public void onActivityResult(int requestCode, int resultCode, Intent data) {    switch(requestCode) {        case 9999:            //File myFile = new File(data.getData().toString());            String path = data.getData().toString();            //View the path            Log.i("Test", "Result URI " + path);            Toast.makeText(getApplicationContext(), "Result URI " +data.getData().toString(), Toast.LENGTH_LONG).show();            //Creating new File for the directory            File directory = new File(path);            File[] files = directory.listFiles();            Log.d("Files", "Size: "+ files.length);            for (int i = 0; i < files.length; i++)            {                //Show the name of the files in the directory                Log.d("Files", "FileName:" + files[i].getName());            }            break;    }}在清單中我也有讀取外部存儲的權(quán)限<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />