一道关于JAVA画图的题 求高人指点...

题目是这样的：
编写一个applet，该程序请求用户输入一组坐标，然后绘制该圆，并显示该圆的直径，周长和面积。使用Ellipse2D.Double对象代表该圆，并使用Graphics2D类的draw方法显示这个圆。

我编写的代码是这样的：
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import javax.swing.*;
import java.awt.event.*;

public class DrawCircle extends JFrame
{
private JLabel lengthLabel,widthLabel;
private JTextField lengthField,widthField;
private Container container;
private JTextArea outputArea;
private int len,hei;

public DrawCircle()
{
super("Drawing a Circle");
container=getContentPane();
container.setLayout(new FlowLayout());

lengthLabel=new JLabel("Enter the length:");
container.add(lengthLabel);
lengthField=new JTextField(10);
container.add(lengthField);

widthLabel=new JLabel("Enter the width:");
container.add(width);
widthField=new JTextField(

public class DrawCircle extends JFrame implements ActionListener {

private JLabel lengthLabel, widthLabel;
private JTextField lengthField, widthField;
private Container container;
private JTextArea outputArea;
private int len, hei;

public DrawCircle() {
super("Drawing a Circle");
setSize(400,400);
setVisible(true);

container = getContentPane();
container.setLayout(new FlowLayout());

lengthLabel = new JLabel("Enter the length:");
container.add(lengthLabel);
lengthField = new JTextField(10);
container.add(lengthField);

widthLabel = new JLabel("Enter the width:");
container.add(widthLabel);
widthField = new JTextField(10);
container.add(widthField);

outputArea = new JTextArea(30, 30);