java - 单击组合框选项时不显示切换大小写字符串

Question

我正在测试此代码，以确保它在完成其余开关案例之前按预期运行。该应用程序运行良好，但是当单击组合框选项时，它应该根据适当的大小写显示一个字符串。我不明白为什么这不起作用。我尝试过调试，但坦白说我没有看到任何问题。任何帮助都会很棒。这是代码:

 package combobox;

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

 public class SolicitorComBox extends JFrame implements ActionListener {
 String[] MuniArray = {"Allepo", "Avalon",};
 JComboBox MuniList = new JComboBox (MuniArray);
 JLabel lblText = new JLabel();

 public static void main(String[] args) {
    SolicitorComBox fr = new SolicitorComBox();
    centerFrame(fr);
    fr.setVisible(true);


 }
 private static void centerFrame(SolicitorComBox fr) {


 }
 public SolicitorComBox() {
    setLayout (new FlowLayout());
    setSize (400, 300);
    setTitle ("Solicitor Search");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    MuniList.setSelectedIndex(0);
    MuniList.addActionListener(this);
    add(MuniList);
    add(lblText);

}
public void actionPerformed(ActionEvent e) {
    if (e.getSource() == MuniList) {
        JComboBox cb = (JComboBox).e.getSource();
        String msg = (String)cb.getSelectedItem();
        switch (msg) {
            case "Allepo": lblText.setText("The attorney is Joe!");
            break;
            case "Avalon": lblText.setText("The attorney is Dana!");
            break;

Answer 1

在actionPerformed()中更改

(JComboBox).e.getSource();

至

(JComboBox) e.getSource();

您必须对 JComboBox 进行强制转换