画像一覧を表示して、その画像のファイルパスを渡したい。

Question

画像の一覧を表示して、その画像のファイルパスを
顔検出のメソッドに渡したいです。
しかし以下のエラーがでて、うまくいきません。
修正すべき部分があれば提案してください。
よろしくお願いします。

参考サイト
http://workpiles.com/2014/07/android-gallary-intent/
https://seesaawiki.jp/w/moonlight_aska/d/%b4%e9%a4%f2%b8%a1%bd%d0%a4%b9%a4%eb

2020-03-30 18:16:21.538 10387-10387/com.example.face_7 E/.example.face_: Unknown bits set in runtime_flags: 0x8000
2020-03-30 18:16:21.669 10387-10423/com.example.face_7 E/Perf: Fail to get file list com.example.face_7
2020-03-30 18:16:21.669 10387-10423/com.example.face_7 E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2020-03-30 18:16:21.669 10387-10423/com.example.face_7 E/Perf: Fail to get file list com.example.face_7
2020-03-30 18:16:21.669 10387-10423/com.example.face_7 E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array

画像のファイルパスを取得するメソッドです。

public class MainActivity extends AppCompatActivity {

    private final int MAX_FACE_NUM = 3;
    private FaceDetector.Face[] mFaces = new FaceDetector.Face[MAX_FACE_NUM];
    private  Bitmap mBmpRes = null;
    private ImageView mView = null;

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

        startActivity();
    }

    public void startActivity() {
        if (Build.VERSION.SDK_INT < 19) {
            Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
            intent.setType("image/jpeg");
            startActivityForResult(Intent.createChooser(intent, "Pick a source"), 0);
        } else {
            Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
            intent.addCategory(Intent.CATEGORY_OPENABLE);
            intent.setType("image/jpeg");
            startActivityForResult(Intent.createChooser(intent, "Pick a source"), 1);
        }
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != RESULT_OK) return;

        if (requestCode == 0) {
            String[] columns = {MediaStore.MediaColumns.DATA};
            Cursor cursor = getContentResolver().query(data.getData(), columns, null, null, null);

            if (cursor.moveToFirst()) {
                ReadPicture(cursor.getString(0));　//ここで渡します！
            }
        } else if (requestCode == 1) {
            String id = DocumentsContract.getDocumentId(data.getData());
            String selection = "_id=?";
            String[] selectionArgs = new String[]{id.split(":")[1]};

            Cursor cursor = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[]{MediaStore.MediaColumns.DATA}, selection, selectionArgs, null);

            if (cursor.moveToFirst()) {

                ReadPicture(cursor.getString(0)); //ここで渡します！
            }
            cursor.close();
        }
    }

顔検出のメソッドです。

    private void ReadPicture(String paths) {

            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inPreferredConfig = Bitmap.Config.RGB_565;

            Bitmap bmpOrg = BitmapFactory.decodeFile(paths, options);

            mBmpRes = bmpOrg.copy(Bitmap.Config.RGB_565, true);
            if (bmpOrg != null) {
                detectFace(bmpOrg);
                mView = (ImageView) findViewById(R.id.imageView);
                mView.setImageBitmap(mBmpRes);

            }
        }

    private void detectFace(Bitmap img) {
        FaceDetector detector = new FaceDetector(img.getWidth(), img.getHeight(),MAX_FACE_NUM);
        int num = detector.findFaces(img, mFaces);
        for (int i = 0; i < num; i++) {
            PointF mid = new PointF();
            mFaces[i].getMidPoint(mid);
            setMark(mFaces[i]);
        }
    }

    private void setMark(FaceDetector.Face face) {
        Canvas canvas = new Canvas(mBmpRes);
        Paint paint = new Paint();
        paint.setColor(Color.RED);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(5);

        PointF mid = new PointF();
        face.getMidPoint(mid);
        canvas.drawCircle(mid.x, mid.y,face.eyesDistance(), paint);
    }