java - 为什么只有 windowGainedFocus() 不起作用？

Question

我有以下代码，我在其中将 WindowListener 添加到我的 JFrame，并且我想重写方法 windowGainedFocus:

    final JFrame jd = new JFrame();
    jd.setLocationRelativeTo(null);
    jd.setSize(300, 425);
    jd.setLayout(null);
    jd.setResizable(false);

    jd.addWindowListener(new WindowAdapter() {
         public void windowGainedFocus(WindowEvent windowEvent){
               System.out.println("TEST");
         }        
    }); 

但它不起作用，当我聚焦此框架时它不会打印“TEST”。但是当我覆盖方法 windowClosing 时它起作用了:

    jd.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
               System.out.println("TEST");
         }        
    }); 

windowGainedFocus() 有什么问题？

Answer 1

jd.addWindowListener(new WindowAdapter() {
     public void windowGainedFocus(WindowEvent windowEvent){
           System.out.println("TEST");
     }        
}); 

应该是:

jd.addWindowFocusListener(new WindowAdapter() {
     public void windowGainedFocus(WindowEvent windowEvent){
           System.out.println("TEST");
     }        
}); 

我知道我讨厌适配器类是有充分理由的。我建议使用监听器而不是适配器。