运行 APPLET小程序是发生错误提示555555

netbuddy

代码如下：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class setbutton extends JApplet
{
Image mm,jj;
JFrame frame1;
JButton mmbn,jjbn;
JLabel label1;
JPanel panel1;
ImageIcon jjcon,mmcon;



public void init()
{
frame1=new JFrame("按钮测试");
    frame1.setLayout(new BorderLayout());
   
    mm=getImage(getCodeBase(),"mm.jpg");
mmcon=new ImageIcon(mm);

jj=getImage(getCodeBase(),"jj.jpg");
jjcon=new ImageIcon(jj);
   
    label1=new JLabel();
    frame1.add(label1,BorderLayout.CENTER);
   
    panel1=(JPanel)getContentPane();
    panel1.setLayout(new GridLayout(1,2));
    mmbn=new JButton("我是MM^_^");
    jjbn=new JButton("我是JJ^_^");
    panel1.add(mmbn);
    panel1.add(jjbn);
   
   
    mmbn.addActionListener(new ActionListener()
    {
   public void actionPerformed(ActionEvent evt)
  {
    label1.setIcon(mmcon);
  }
  });
   
     jjbn.addActionListener(new ActionListener()
    {
   public void actionPerformed(ActionEvent evt)
  {
    label1.setIcon(jjcon);
  }
  });
    frame1.add(panel1,BorderLayout.SOUTH);
   
    frame1.pack();
    frame1.show();

    }
  }
   


I:\JAVA>appletviewer setbutton.html
java.lang.Error: Do not use javax.swing.JFrame.setLayout() use javax.swing.JFram
e.getContentPane().setLayout() instead
        at javax.swing.JFrame.createRootPaneException(JFrame.java:465)
        at javax.swing.JFrame.setLayout(JFrame.java:531)
        at setbutton.init(setbutton.java:20)
        at sun.applet.AppletPanel.run(AppletPanel.java:353)
        at java.lang.Thread.run(Thread.java:534)

netbuddy

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class setbutton extends JApplet
{
Image mm,jj;
Frame frame1;
JButton mmbn,jjbn;
JLabel label1;
JPanel panel1;
ImageIcon jjcon,mmcon;



public void init()
{
frame1=new Frame("按钮测试");
    frame1.setLayout(new BorderLayout());
   
    mm=getImage(getCodeBase(),"mm.jpg");
mmcon=new ImageIcon(mm);

jj=getImage(getCodeBase(),"jj.jpg");
jjcon=new ImageIcon(jj);
   
    label1=new JLabel();
    frame1.add(label1,BorderLayout.CENTER);
   
    panel1=(JPanel)getContentPane();
    panel1.setLayout(new GridLayout(1,2));
    mmbn=new JButton("我是MM^_^");
    jjbn=new JButton("我是JJ^_^");
    panel1.add(mmbn);
    panel1.add(jjbn);
    frame1.add(panel1,BorderLayout.SOUTH);
   
    mmbn.addActionListener(new ActionListener()
    {
   public void actionPerformed(ActionEvent evt)
  {
    label1.setIcon(mmcon);
  }
  });
   
     jjbn.addActionListener(new ActionListener()
    {
   public void actionPerformed(ActionEvent evt)
  {
    label1.setIcon(jjcon);
  }
  });
   
   
    frame1.pack();
    frame1.show();

    }
  }
   

问题找到，应该用Frame类，不是JFrame类：）
可是他们应用的环境有什么不同呢？
一个是用在Application程序一个用在applet？