为什么只有windowGainedFocus（）不起作用？

Question

我有以下代码，我将WindowListener添加到我的JFrame中，我想覆盖方法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，当我对焦这个框架时，它不会打印“TEST”。 但当我覆盖方法windowClosing时，它可以工作：

    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");
     }        
}); 

我知道有一个很好的理由我讨厌适配器类..我建议使用监听器而不是适配器。