public class Main extends JFrame{
    public static void main(String[] args) {
        JFrame jp1 = new JFrame();
        jp1.setTitle("Diagram");
        Print m = new Print();
        jp1.setLayout(null);
        jp1.setSize(500,500);
        m.setBounds(0,0,500,500);
        jp1.add(m);
        jp1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jp1.setVisible(true);
    }
    static class Print extends JPanel{
        public void drawDiagram(Graphics g, double[] x, double[] y){
            g.setColor(Color.BLUE);
            int scale = 100;
            int lastX = 0, lastY = 0;
            for (int i = 0; i < x.length; i++) {
                g.drawLine(lastX*scale, lastY*scale,(int) x[i] * scale,(int) y[i]* scale);
                lastX = (int) x[i];
                lastY = (int) y[i];
            }
        }
    }

}

I am using java swing and I dont understand why my digram isnt printing.
I have tried using object of class Main but it didnt help.
Could ypu help me with my problem?
Thanks in advance