How can I close the camera with java and OpenCV?

I'm new in the world of StackOverflow and in OpenCV programming. I've opened my camera with some Java code and it worked because the light of camera was on, but when I tried to close the camera, I failed.

Code:

public class camera {

    public static void main(String[] args)  {
        System.loadLibrary("opencv_java244");
        VideoCapture camera = new VideoCapture(0);
        if (camera.isOpened())
             System.out.println("Camera is ready!");
        else {
             System.out.println("Camera Error!");
             return;
        }
        Mat newMat = new Mat();

        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            //e.printStackTrace();
        }

        camera.read(newMat);
        Highgui.imwrite("testfile.jpg", newMat);

        camera.release();
        if (camera.isOpened()) {
            System.out.println("Camera is running!");
        }
        else {
            System.out.println("Camera closed!");
        }
    }
}

result:

Camera is ready!
Camera closed!

I really got the picture, but the light was still on! P.S. Everytime when I try to open my camera, my computer will open a drive software named YouCam, and I must close it manually to release the camera.

Try capture.retrieve() instead of capture.read(). Here is a snapshot which works for me without using even Thread.sleep() VideoCapture capture = new VideoCapture(0);

    if (!capture.isOpened()) {
        imagePanel.add(new JLabel("Oops! Your camera is not working!"));
        return;
    } 
    Mat frame = new Mat();
    capture.retrieve(frame);
    frame = FaceDetector.detect(frame);
    BufferedImage image = GestureUtil.matToBufferedImage(frame);*/
    imagePanel.setImage(image);
    imagePanel.repaint();
    String window_name = "Capture - Face detection.jpg";
    Highgui.imwrite(window_name, frame);

    capture.release();

I have using this along with Swing. However, you can ignore swing code. Hope this helps