java编写一个字母大小写转换器？

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class CaseConverter extends JFrame {

private JTextField inputField;

private JTextField outputField;

private JButton capitalButton;

private JButton lowercaseButton;

public CaseConverter() {

// 设置窗口标题

setTitle("Case Converter");

// 设置窗口布局为FlowLayout

setLayout(new FlowLayout());

// 创建组件

inputField = new JTextField(20);

outputField = new JTextField(20);

capitalButton = new JButton("Capital");

lowercaseButton = new JButton("Lowercase");

// 将组件添加到窗口中

add(inputField);

add(outputField);

add(capitalButton);

add(lowercaseButton);

// 向按钮添加按压事件监听器

capitalButton.addActionListener(new CapitalListener());

lowercaseButton.addActionListener(new LowercaseListener());

}

// 定义Capital按钮的按压事件监听器

private class CapitalListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

// 从输入文本框中获取输入字符串

String input = inputField.getText();

// 将字符串中的大写字母转换为小写字母，其它字符不变

String output = input.toLowerCase();