Java - kreslenie do Canvasa

import java.awt.*;
import java.awt.Graphics.*;
import java.awt.Canvas.*;
import javax.swing.*;
import javax.swing.JDialog.*;
import javax.swing.JFrame.*;

public class test extends JFrame {
    public test() {
        initComponents();
    }

    private void initComponents() {
        panel = new javax.swing.JPanel();
        canvas = new java.awt.Canvas();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        panel.setBackground(new java.awt.Color(255, 0, 0));
        panel.setLayout(null);
        canvas.setBackground(new java.awt.Color(0, 255, 0));
        panel.add(canvas);
        canvas.setBounds(30, 20, 150, 140);
        getContentPane().add(panel, java.awt.BorderLayout.CENTER);
        pack();
    }

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new test().setVisible(true);
            }
        });
    }

    private java.awt.Canvas canvas;
    private javax.swing.JPanel panel;
}

canvas.drawLine(10, 20, 300, 100);

public void paint(Graphics g) {
    g.drawLine(10,20,300,100);
    }

private class MyCanvas extends Canvas {
       public void paint(Graphics g) {
          g.drawLine(10,20,300,100);
       }
    }

...
canvas=new MyCanvas();
...