How do GLCanvas and JFrame work together?

Question

I have this simple first program which runs correctly.

public class OpenGL extends JFrame implements GLEventListener {

    GLCanvas glCanvas;

    public OpenGL() {
        setTitle("First OpenGL Program");
        setSize(600, 600);
        setLocation(0, 0);
        glCanvas = new GLCanvas();
        glCanvas.addGLEventListener(this);
        this.add(glCanvas);
        setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public static void main (String[] args) {
        new OpenGL();
    }
}

But I'm not sure what the following lines of code do:

glCanvas.addGLEventListener(this);
this.add(glCanvas);

Answer 1

我在这里找到了对我的问题的很好的解释