FaceRecognition with OpenCv, NDK and Android studio failed! [closed]

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I was trying to run this code to take a photo and recognize tho photo owner, at first the user clicks the button Train and takes a picture than enter its name, after that he clicks on Recognize button and take a picture if the picture was saved the apps recognize its face if not it shows unknown person for example. The app runs good but when it crashes sometimes with this error:

CvException [org.opencv.core.CvException: cv::Exception: OpenCV(4.0.0-pre) E:\AssemCourses\opencv-master\modules\core\src\matrix.cpp:235: error: (-215:Assertion failed) s >= 0 in function 'setSize'

The error in logcat refers to the method trainfaces :

Class TrainActivity.java:

    private boolean trainfaces() {
        if(images.isEmpty())
            return false;
        List<Mat> imagesMatrix = new ArrayList<>();
        for (int i = 0; i < images.size(); i++)
            imagesMatrix.add(images.get(i));
        Set<String> uniqueLabelsSet = new HashSet<>(imagesLabels); // Get all unique labels
        uniqueLabels = uniqueLabelsSet.toArray(new String[uniqueLabelsSet.size()]); // Convert to String array, so we can read the values from the indices

        int[] classesNumbers = new int[uniqueLabels.length];
        for (int i = 0; i < classesNumbers.length; i++)
            classesNumbers[i] = i + 1; // Create incrementing list for each unique label starting at 1
        int[] classes = new int[imagesLabels.size()];
        for (int i = 0; i < imagesLabels.size(); i++) {
            String label = imagesLabels.get(i);
            for (int j = 0; j < uniqueLabels.length; j++) {
                if (label.equals(uniqueLabels[j])) {
                    classes[i] = classesNumbers[j]; // Insert corresponding number
                    break;
                }
            }
        }
        Mat vectorClasses = new Mat(classes.length, 1, CvType.CV_32SC1); // CV_32S == int
        vectorClasses.put(0, 0, classes); // Copy int array into a vector

        recognize = LBPHFaceRecognizer.create(3,8,8,8,200);
        recognize.train(imagesMatrix, vectorClasses);
        if(SaveImage())
            return true;

        return false;
    }

The Lines of Errors mentionned in the logcat refers to those java code lines :

In TrainActivity.java:

recognize = LBPHFaceRecognizer.create(3,8,8,8,200);
    recognize.train(imagesMatrix, vectorClasses);

And

if(trainfaces()) {
            images.clear();
            imagesLabels.clear();
        }

Do you guys have any idea about this problem and how to fix it?

PS: I am a beginner with OpenCv