java jframe 焦点_java – 如何将JFrame设置为始终处于焦点

我想制作一个始终具有焦点的JFrame,并且在它关闭之前不能失去焦点,我已经将它设置为始终在顶部并且我尝试了这段代码：

import java.awt.event.*;

import javax.swing.*;

public class Viewer extends JFrame WindowFocusListener

{

public Viewer()

{

addWindowFocusListener(this);

setAlwaysOnTop(true);

this.setFocusable(true);

this.setFocusableWindowState(true);

panel = new JPanel();

setSize(WIDTH,HEIGHT);

setLocation(X,Y);

setResizable(false);

setVisible(true);

}

public void windowGainedFocus(WindowEvent e){}

public void windowLostFocus(WindowEvent e)

{

toFront();

requestFocusInWindow();

System.out.println("focus lost");

}

private JPanel panel;

private static final int WIDTH = 200;

private static final int HEIGHT = 200;

private static final int X = 100;

private static final int Y = 100;

public static void main(String args[]){new Viewer();}

}

我不明白为什么这段代码不起作用,谁能看到我做错了什么？提前致谢.