写一个简单的java程序

import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class CircleFrame {
private Circle[] circles = null;
private JFrame frame = null;
final int circleNumber = 20;
final int maxCircleDiameter = 50;
private final Color contactColor = Color.BLACK;
private final Color apartColor = Color.BLUE;

public CircleFrame() {
initFrame();
initCircle();
drawColor();
showCircle();
}

private void showCircle() {
JPanel panel = new MyPanel();
panel.setBounds(0, 0, 800, 600);
Container container = frame.getContentPane();
container.setLayout(null);
container.add(panel);
}

class MyPanel extends JPanel {
private static final long serialVersionUID = 1L;
public void paint(Graphics graphics) {
for (int i = circles.length - 1; i >