OpenCv Image comparing Crash on BOWImgDescripterExtractor.compute in Android

I want to find similar images in gallery using OpenCv java Android and what should be the parameter of BOWImgDescriptorExtractor extractor = BOWImgDescriptorExtractor.__fromPtr__(matches.nativeObj);
or how to create object of this class BOWImgDescriptorExtractor

private boolean compareMats(Mat img1, Mat img2) {
    FastFeatureDetector detector = FastFeatureDetector.create();
    //matcher image descriptors
    MatOfDMatch matches = new MatOfDMatch();
    // bowDe = new BOWImgDescriptorExtractor(_detector, _matcher);
    BOWImgDescriptorExtractor extractor = BOWImgDescriptorExtractor.__fromPtr__(matches.nativeObj);
    DescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE_HAMMING);
    Mat descriptors1 = new Mat();

    MatOfKeyPoint keypoints1 = new MatOfKeyPoint();
    detector.detect(img1, keypoints1);
    try {
        extractor.compute(img1, keypoints1, descriptors1);
    } catch (Exception e) {
        e.printStackTrace();
        Log.d(TAG, "compareMats_: " + e.getMessage());
    }

    //second image
    // Mat img2 = Imgcodecs.imread(path2);
    //BOWImgDescriptorExtractor extractor1 = BOWImgDescriptorExtractor.__fromPtr__(img2.getNativeObjAddr());
    Mat descriptors2 = new Mat();
    MatOfKeyPoint keypoints2 = new MatOfKeyPoint();
    detector.detect(img2, keypoints2);
    try {
        extractor.compute(img2, keypoints2, descriptors2);
    } catch (Exception e) {
        e.printStackTrace();
        Log.d(TAG, "compareMats: " + e.getMessage());
    }


    matcher.match(descriptors1, descriptors2, matches);

    // Filter matches by distance
    MatOfDMatch filtered = filterMatchesByDistance(matches);

    int total = (int) matches.size().height;
    int Match = (int) filtered.size().height;
    Log.d("LOG", "total:" + total + " Match:" + Match);
    System.gc();
    return Match > total * 0.8;
}

static MatOfDMatch filterMatchesByDistance(MatOfDMatch matches) {
    List<DMatch> matches_original = matches.toList();
    List<DMatch> matches_filtered = new ArrayList<DMatch>();

    int DIST_LIMIT = 30;
    // Check all the matches distance and if it passes add to list of filtered matches
    Log.d("DISTFILTER", "ORG SIZE:" + matches_original.size() + "");
    for (int i = 0; i < matches_original.size(); i++) {
        DMatch d = matches_original.get(i);
        if (Math.abs(d.distance) <= DIST_LIMIT) {
            matches_filtered.add(d);
        }
    }
    Log.d("DISTFILTER", "FIL SIZE:" + matches_filtered.size() + "");

    MatOfDMatch mat = new MatOfDMatch();
    mat.fromList(matches_filtered);
    return mat;
}

but getting Following error At extractor.compute(img2, keypoints2, descriptors2);

A/libc: Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x42ff0068 in tid 19304 (ailestestopencv), pid 19304 (ailestestopencv)

It would be highly appreciated if anyone answer me.