我真的被困在如何编程的问题上了。需要在以下条件下使用Java drawArc方法绘制一系列8个同心圆

使用导入java.util.Random库

1. 规定在任意位置开始绘图(即x-y坐标必须随机计算)。
2. 为每个圆圈提供一个随机颜色
3. 为每个圆提供一个随机直径

我目前的代码能够得到每个圆圈的随机颜色，但不清楚如何满足其他随机条件。

// Exercise 12.6 Solution: CirclesJPanel.java
// This program draws concentric circles
import java.awt.Graphics;
import javax.swing.JPanel;
public class ConcentricCircles extends JPanel
  // draw eight Circles separated by 10 pixels
   public void paintComponent( Graphics g )
      Random random = new Random();
      super.paintComponent( g );
      // create 8 concentric circles
      for ( int topLeft = 0; topLeft < 80; topLeft += 10 )
         int radius = 160 - ( topLeft * 2 );
         int r = random.nextInt(255);
         int gr = random.nextInt(255);
         int b = random.nextInt(255);
         Color c = new Color(r,gr,b);
         g.setColor(c);
         g.drawArc( topLeft + 10, topLeft + 25, radius, radius, 0, 360 );
      } // end for
// This program draws concentric circles
import javax.swing.JFrame;
public class ConcentricCirclesTest extends JFrame {
    * @param args
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JFrame frame=new JFrame("Concentric Circles");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ConcentricCircles cCirclesJPanel = new ConcentricCircles();
        frame.add(cCirclesJPanel);
        frame.setSize(200,250);
        frame.setVisible(true);
    }//end main