java - 如何从匿名 ActionListener 访问 JFrame 以在框架中添加面板？

Question

如果单击某个按钮，我想在框架中添加一个 JPanel，但我不知道如何从匿名 ActionListener 管理它。这是代码:

public class MyFrame extends JFrame {
   JPanel panel;
   JButton button;
   public MyFrame() {
      button = new JButton("Add panel");
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent event) {
            panel = new JPanel();
            //here I want to add the panel to frame: this.add(panel), but I don't know
            //how to write that. In these case "this" refers to ActionListener, not to
            //frame, so I want to know what to write instead of "this" in order to
            //refer to the frame
         }
      }
      this.add(button);
  }

提前致谢!

Answer 1

here I want to add the panel to frame: this.add(panel), but I don't know how to write that. In these case "this" refers to ActionListener, not to frame, so I want to know what to write instead of "this" in order to refer to the frame

代替 this.add(...) 只需使用 add(..) 或者您可以使用 MyFrame.this.add(..) 因为在匿名类中使用 this 意味着您指的是 ActionListener 实例。

实际上，您可能还需要在添加组件后调用revalidate() 和repaint()。