java下拉框怎么安装监听器

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

public class ComboBoxListenerExample {

    public static void main(String[] args) {
        // 创建下拉框
        JComboBox<String> comboBox = new JComboBox<>(new String[] {"Option 1", "Option 2", "Option 3"});

        // 创建监听器类
        class ComboBoxActionListener implements ActionListener {
            @Override
            public void actionPerformed(ActionEvent e) {
                // 获取下拉框中选定的选项
                String selectedItem = (String) comboBox.getSelectedItem();

                // 处理选项更改
                System.out.println("Selected item: " + selectedItem);
            }
        }

        // 创建监听器实例
        ActionListener listener = new ComboBoxActionListener();

        // 将监听器添加到下拉框
        comboBox.addActionListener(listener);

        // 创建和显示窗口
        JFrame frame = new JFrame("ComboBox Listener Example");
        frame.add(comboBox);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}