java - 从 JFrame 引用 JPanel 组件

Question

我有一个在 JFrame 中创建 JPanel 的应用程序，如下所示:

public class Frame1{
    public Frame1(){
        Frame2 f2 = new Frame2();
        f2.pack();
        f2.setVisible(true);
    }

    class Frame2 extends JFrame{
        public Frame2(){
            JPanel p1 = new JPanel();
            JTextField txt1 = new JTextField("Test",12);
            p1.add(txt1);
            JButton btn1 = new JButton("Click Me!");
            p1.add(btn1);
            add(p1);
            btn1.addActionListener(this);
        }
        public void actionPerformed(ActionEvent e){
            JOptionPane.showDialog(null,text of the textbox);
        }
    }
}

有没有办法引用文本字段，即使它不是字段变量并且只是在构造函数中声明(this.getRootPane().getParent() 会给我框架我相信，但我从那里去哪里)？

Answer 1

再次重申，为什么不让 JTextField 成为该类的私有(private)非静态字段:

import java.awt.event.*;
import javax.swing.*;

public class Frame1 {
   public Frame1() {
      Frame2 f2 = new Frame2();
      f2.pack();
      f2.setVisible(true);
   }

   class Frame2 extends JFrame implements ActionListener {
      private JTextField txt1;

      public Frame2() {
         JPanel p1 = new JPanel();

         // JTextField txt1 = new JTextField("Test", 12);
         txt1 = new JTextField("Test", 12);

         p1.add(txt1);
         JButton btn1 = new JButton("Click Me!");
         p1.add(btn1);
         add(p1);
         btn1.addActionListener(this);
      }

      // if outside classes need to see the text
      public String getTxt1Text() {
         return txt1.getText();
      }

      public void actionPerformed(ActionEvent e) {
         JOptionPane.showMessageDialog(this, txt1.getText());
      }
   }
}