[Java] [Component and event processing] String case conversion

MyFrame:

package com.itheima;

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

public class MyFrame extends JFrame {
    
    
    JTextField text1, text2;
    JButton button;
    ButtonGroup buttonGroup;
    JRadioButton radio1, radio2;
    PoliceListen policeListen;


    public MyFrame() {
    
    
        init();
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    void init() {
    
    
        setLayout(new FlowLayout());
        text1 = new JTextField(16);
        text2 = new JTextField(16);
        button = new JButton("转换");
        buttonGroup = new ButtonGroup();
        radio1 = new JRadioButton("大写");
        radio2 = new JRadioButton("小写");
        radio1.setActionCommand("大写");
        radio2.setActionCommand("小写");
        add(text1);
        buttonGroup.add(radio1);//设置命令字符串
        buttonGroup.add(radio2);
        add(button);
        add(radio1);
        add(radio2);
        add(text2);
        policeListen = new PoliceListen();
        button.addActionListener(policeListen);
    }

    private class PoliceListen implements ActionListener {
    
    


        @Override
        public void actionPerformed(ActionEvent e) {
    
    
            String command = buttonGroup.getSelection().getActionCommand();//获取按钮组中被挑选的组件命令字符串
            boolean upper = command.equals("大写");
            String s = text1.getText();
            if (upper) {
    
    
                text2.setText(s.toUpperCase());
            } else
                text2.setText(s.toLowerCase());
        }
    }
}

Main:

package com.itheima;
public class Main {
    
    
    public static void main(String[] args) {
    
    
        MyFrame myFrame = new MyFrame();
        myFrame.setBounds(100,100,240,160);
        myFrame.setTitle("字符串大小写转换");

    }
}