怎么判断一个框体是否关闭了？求解

如何判断一个框体是否关闭了？求解
有两个框体JFrame jf1,jf2
当jf2出现时jf1设为不可见;
当jf2关闭时jf1又可见了。求解答！
如何判断jf2已经关闭了？

[解决办法]
加个监听不就完了

Java code

        Frame f = new Frame();                f.addWindowListener(new WindowListener() {            @Override            public void windowActivated(WindowEvent arg0) {                // TODO Auto-generated method stub                            }            @Override            public void windowClosed(WindowEvent arg0) {                // TODO Auto-generated method stub                System.out.println("关闭");            }            @Override            public void windowClosing(WindowEvent arg0) {                // TODO Auto-generated method stub                            }            @Override            public void windowDeactivated(WindowEvent arg0) {                // TODO Auto-generated method stub                            }            @Override            public void windowDeiconified(WindowEvent arg0) {                // TODO Auto-generated method stub                            }            @Override            public void windowIconified(WindowEvent arg0) {                // TODO Auto-generated method stub                            }            @Override            public void windowOpened(WindowEvent arg0) {                // TODO Auto-generated method stub                            }        });
[解决办法]
开启F2的时候  设置F1 visible = false  
 开启F1的时候  设置F2 visible = false  

[解决办法]
boolean flag标记一下。通过flag判断。