更改JComboBox的内部弹出窗口(JList)的边框颜色

import javax.swing.*;
import javax.swing.plaf.basic.BasicComboPopup;
import java.awt.*;

public class ComboBoxExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("ComboBox Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 创建一个JComboBox
        JComboBox<String> comboBox = new JComboBox<>(new String[]{"Option 1", "Option 2", "Option 3"});
        
        // 获取JComboBox的弹出窗口
        BasicComboPopup popup = (BasicComboPopup) comboBox.getAccessibleContext().getAccessibleChild(0);
        
        // 设置弹出窗口的边框颜色
        popup.setBorder(BorderFactory.createLineBorder(Color.RED));

        frame.add(comboBox);
        frame.pack();
        frame.setVisible(true);
    }
}