不太难的问题,我有思路,但没做出来.50分啊~

Question

singleton模式？？？
不用吧？？？
判断子窗体关闭的事件里控制按钮是否可用就行了

Answer 1

随便改了一下，功能能出来：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;class Main extends JFrame implements ActionListener 
{
   private JPanel pan1;
   private JButton Jb1,Jb2;
   private Container con;
   private JFrame newFrom;
   private ActionEvent aEvent;   public Main()
   {
     super("test");
     setDefaultCloseOperation(EXIT_ON_CLOSE);
                buildFrame();
                  addAction();
   }   protected void newFrom(ActionEvent e)
   {
                newFrom=new JFrame();
                this.aEvent = e;
                newFrom.addWindowListener(new WindowAdapter(){
                public void windowClosing(WindowEvent e) {
                newFrom.setVisible(false);         
                ((JButton)aEvent.getSource()).setEnabled(true);
                }
                });
                newFrom.setTitle("新窗体");
                newFrom.setSize(300,300);
                newFrom.show();
   }   protected void buildFrame()
   {
             con=getContentPane();
             pan1=new JPanel();
             Jb1=new JButton("1");
             Jb2=new JButton("2");
             pan1.setLayout(new GridLayout(2,1));
          pan1.add(Jb1);
          pan1.add(Jb2);
          con.add(pan1);
      setSize(400,400);
          show();
   }
   protected void addAction()
   {
               Jb1.addActionListener(this);
                Jb2.addActionListener(this);
   }
   public static void main(String args[])
   {
           new Main();
   }   public void actionPerformed(ActionEvent e) 
   {
                newFrom(e);
                ((JButton)e.getSource()).setEnabled(false);
   }
}