Retrieve R-CNN Mask in Java

I’m using R-CNN to retrieve a mask of the recognized objects.

    String modelWeights="frozen_inference_graph.pb";
    String textGraph="mask_rcnn_inception_v2_coco_2018_01_28.pbtxt";
    Net net = Dnn.readNetFromTensorflow(modelWeights, textGraph);

The bounding box of the objects is found an can be displayed

        java.util.List<Mat> result = new java.util.ArrayList<Mat>(3);
        java.util.List<java.lang.String> outBlobNames = new ArrayList();
        net.forward(result, outBlobNames);

According to Using Java with OpenCV and Mask_RCNN - Stack Overflow I’m retrieving the mask by:

       Mat numClasses = result.get(0);
       numClasses = numClasses.reshape(1, (int) / 7);
       Mat numMasks = result.get(1);
       numMasks = numMasks.reshape(1, (int) / 90);
       Mat reshape = numMasks.reshape(1, (int) ( / (15 * 15)));

To paint the mask I’m using the following code:

       List<MatOfPoint> contours = new ArrayList<>();
       Mat hierarchy = new Mat();
       Imgproc.findContours(reshape,contours,hierarchy,Imgproc.RETR_TREE,            Imgproc.CHAIN_APPROX_SIMPLE);
       for (int i = 0; i < contours.size(); i++) {
                  Scalar color = new Scalar(125);
                  Imgproc.drawContours(reshape, contours, i, color, 2, 1, hierarchy, 0, new Point());

As a result I get more than 14000 Contours but no proper result. Is this really the correct way?
How to select a certain found object?