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

public class WindowChoice extends JFrame implements ItemListener,ActionListener{
    JComboBox choice;
    JTextField text;
    JTextArea area;
    JButton add,del;
    public WindowChoice(){
        init();
        setLocation(300,300);
        setSize(800,600);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    void init(){
        setLayout(new FlowLayout());
        choice = new JComboBox();
        text = new JTextField();
        area = new JTextArea(10,10);
        choice.addItem("音乐天地");
        choice.addItem("网络游戏");
        choice.addItem("单机游戏");
        choice.addItem("聊天室");
        add = new JButton("添加");
        del = new JButton("删除");//这里有修改过
        add.addActionListener(this);
        text.addActionListener(this);
        del.addActionListener(this);
        choice.addItemListener(this);
        add(choice);
        add(text);
        add(add);
        add(new JScrollPane(area));
    }
    public void itemStateChanged(ItemEvent e){
        String name = choice.getSelectedItem().toString();
        int index = choice.getSelectedIndex();
        area.setText("\n"+index+":"+name);  //这里修改过

    }
    public void actionPerformed(ActionEvent e){
        if(e.getSource() == add || e.getSource() == text){
            String name = text.getText();
            if(name.length()>0){
                choice.addItem(name);
                choice.setSelectedItem(name);
                area.append("\n列表添加："+name);

            }

        }
        else if(e.getSource() == del){
            area.append("\n列表删除："+choice.getSelectedItem());
            choice.remove(choice.getSelectedIndex());
        }
    }

    public static void main(String[] args) {
        new WindowChoice();
    }
}

------解决方案--------------------