使用Java编写GUI对话框的教程

import java.applet.*
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class MyWindow extends JFrame implements ActionListener{
  private JButton button1,button2;
  private static int flg=0;
  private static JTextField text1,text2;
  Mywindow(String s){
    super(s);
    Container con = this.getContentPane();
    con.setLayout(new GridLayout(2,2));
    this.setSize(200,100);
    this setLocation(100,100);
    button1 = new JButton("选择水果");
    button2 = new JButton("选择食品");
    button1.addActionListener(this);
    button2.addActionListener(this);
    text1 = new JTextField(20);
    text2 = new JTextField(20);
    con.add(button1);
    con.add(button2);
    con.add(text1);
    con.add(text2);
    this.setVisible(true);
    this.pack();
  }
  public static void returnName(String s){
    if(flg ==1)
      text1.setText("选择的水果是："+s);
    else if(flg == 2)
      text2.setText("选择的食品是："+s);
  }
  public void actionPerformed(ActionEvent e){
    MyDialog dialog;
    if(e.getSource()==button1){
      dialog = new MyDialog(this,"水果");
      dialog.setVisible(true);
      flg =1;
    }
    else if(e.getSource()==button2){
      dialog =new MyDialog(this,"食品");
      dialog.setVisible(true);
      flg=2;
    }
  }
}
class MyDialog extends JDialog implements ActionListener{
  JLabel title;
  JTextField text;
  JButton done;
  Mydialog(JFrame F,String s){
    super(F,s,true);//模态
    Container con = this.getContentPane();
    title = new JLabel("输入"+s+"名称");
    text = new JTextField(10);
    text.setEditable(true);
    con.setLayout(new FlowLayout());
    con.setSize(200,100);
    setModal(false);
    done = new JButton("确定");
    done.addActionListener(this);
    con.setVisible(true);
    this.pack();
  }
  public void actionPerformed(ActionEvent e){
    MyWindow.returnName(text.getText());
    setVisible(false);
    dispose();
  }
}
public class Example6_6 extends Applet{
  MyWindow window;
  MyDialog dialog;
  public void init(){
    window = new MyWindow("带对话框窗口");
  }
}

public void actionPerformed(ActionEvent e){
  if(e.getSource()==text){
    MyWindow.returnName(text.getText());
  }
  else if(e.getSource()==done){
    MyWindow.returnName(text.getText());
    setVisible(false);
    dispose();//清除资源
  }
}

  int result = JOptionPane.showConfirmDialog(parent,“确实要退出吗”, “退出确认“，JOptionPane.YES_NO_CANCEL_OPTION);

  String result = (String)JOptionPane.showInputDialog(parent,
    “请选择一项运动项目”, “这是运动项目选择对话框”,
    JOptionPane.QUESTION_MESSAGE,null,
    new Object[]{“踢足球“，“打篮球”，“跑步”，“跳绳”}，“跑步”);

  JOptionPane.showMessageDialog(parent, “这是一个Java程序”,
    “我是输出信息对话框”，JOptionPane.PLAIN_MESSAGE);