我無法從JList中選擇項目

Question

這是我的代碼的一部分，我遇到的問題是我無法從列表中選擇項目（當我的界面運行時，我不能按項目來選擇它）！

DefaultListModel model = new DefaultListModel ();
JList list=new JList(model);
comboBox_2.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
          JComboBox comboBox_2 = (JComboBox) e.getSource();
           Object selected = comboBox.getSelectedItem();
           Object selected_2 = comboBox_2.getSelectedItem();
         if(selected.toString().equals("1")) {   
              if (selected_2.toString().equals("Oils")) {
                try{
                    Connection conn=DriverManager.getConnection("jdbc:mysql://localhost/flyer","root","000");
                    String query="SELECT item_name FROM item WHERE ( month(expired_date) = month(curdate()) AND day(expired_date) >= day(curdate()) AND year(expired_date) = year(curdate()) AND category_id=1) OR ( month(expired_date) = month(curdate()) +1 AND day(expired_date) <= day(curdate()) AND year(expired_date) = year(curdate()) AND category_id=1) ";
                    Statement st= conn.createStatement();
                    ResultSet r=st.executeQuery(query);
                    model.removeAllElements();
                    while(r.next()){
                        String itemCode = r.getString("item_name"); 
                        model.addElement(itemCode);
                }}
                catch (Exception ex){
                    System.err.println(e);

                }}

Answer 1

檢查您的輸出，看看是否有任何異常。 另外，您嘗試在catch(Exception ex)塊中打印動作偵聽器。

PS：您的代碼確實很亂。 您應該修復縮進。