如何在Jlist中使用下面提到的Jcombobox代码进行转换

Question

因为在Jcombobox中，我认为不允许多选，但可以使用jlist。

addActionListener中的错误

public class SwingControlDemo {
  private JFrame mainFrame;
  private JLabel headerLabel;
  private JLabel statusLabel;
  private JPanel controlPanel;

  public SwingControlDemo() {
    prepareGUI();
  }
  public static void main(String[] args) {
    SwingControlDemo swingControlDemo = new SwingControlDemo();
    swingControlDemo.showListDemo();
  }
  private void prepareGUI() {
    mainFrame = new JFrame("Java Swing Examples");
    mainFrame.setSize(400, 400);
    mainFrame.setLayout(new GridLayout(3, 1));

    mainFrame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent windowEvent) {
        System.exit(0);
      }
    });
    headerLabel = new JLabel("", JLabel.CENTER);
    statusLabel = new JLabel("", JLabel.CENTER);
    statusLabel.setSize(350, 100);

    controlPanel = new JPanel();
    controlPanel.setLayout(new FlowLayout());

    mainFrame.add(headerLabel);
    mainFrame.add(controlPanel);
    mainFrame.add(statusLabel);
    mainFrame.setVisible(true);
  }
  private void showListDemo() {
    headerLabel.setText("JList");

    //final DefaultListModel 
    mainMenu = new DefaultListModel();
    String[] choices = {
      "Redeem",
      "Prepaid",
      "FRC",
      "Offices",
      "Individual Bags",
      "Gift Subscription",
      "E-Gift Card",
      "My Account",
      "Wp-Admin",
      "Shipstaion",
      "Any date changes"
    };

    final JList mainList = new JList(choices);
    mainList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    mainList.setSelectedIndex(0);
    mainList.setVisibleRowCount(5);
    JScrollPane mainListScrollPane = new JScrollPane(mainList);

    mainList.setBounds(125, 110, 173, 30);
    mainList.setSelectedIndex(0);
    mainList.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        // final DefaultListModel 
        subMenu = new DefaultListModel();
        String[] choices1 = {
          "Redeem Remaining & Redeem Gift Card",
          "Redeem of Tasting Kit Sub",
          "US & NON-US Redeem",
          "Manually Created Vouchers"
        };
        final JList subList1 = new JList(choices1);
        subList1.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
        subList1.setSelectedIndex(0);
        subList1.setVisibleRowCount(5);
        JScrollPane subListScrollPane1 = new JScrollPane(subList1);
        controlPanel.add(subListScrollPane1);
      }
    });

    // String[] choices2 = {"Prepaid US","Prepaid Non-US","Prepaid Auto Renewal", "Prepaid Don't Renew","Prepaid Auto Renewal Failed Payment","With Enable Dates"}; 
    // final JList subList2 = new JList(choices2); 
    // subList2.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); 
    // subList2.setSelectedIndex(0); 
    // subList2.setVisibleRowCount(5); 
    // JScrollPane subListScrollPane2 = new JScrollPane(subList2); 
    //controlPanel.add(subListScrollPane2);

    JButton showButton = new JButton("Show main menu");
    JButton showButton1 = new JButton("Show sub menu");

    showButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        String data = "";
        if (mainList.getSelectedIndex() != -1) {
          data = "Main List Selected: " + mainList.getSelectedValue();
          statusLabel.setText(data);
        }

        statusLabel.setText(data);
      }
    });
    showButton1.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        String data = "";

        if (subList1.getSelectedIndex() != -1) {
          data += " Sub List selected: ";
          for (Object sub: subList1.getSelectedValues()) {
            data += sub + " ";
          }
        }
        statusLabel.setText(data);
      }
    });

    controlPanel.add(mainListScrollPane);
    controlPanel.add(showButton);
    controlPanel.add(showButton1);
    mainFrame.setVisible(true);
  }
}