java - 从数据库中选择并显示在组合框-GUI 中

Question

我试图从数据库中选择项目的名称，然后将其保存到一个数组中，以便稍后将其添加到 JComboBox，但由于某种原因，它根本没有从数据库中获取它。

这是应该执行此操作的代码部分:

public BirthdayForm()
{
    super("Birthday Party Supplies Rental Form");
    String url = "jdbc:mysql://localhost/";
    String dbName = "partySupplies";
    String driver = "com.mysql.jdbc.Driver";
    String username = "root";
    String pw = "";
    Class.forName(driver).newInstance();
    Connection conn = DriverManager.getConnection(url+dbName,username,pw);


    setLayout(new FlowLayout());

    String[] list = null;
    chooseItem = new JLabel("Choose Item:");
    String selectSQL = "SELECT productName FROM birthday where productName = ?";
    PreparedStatement preparedStatement = conn.prepareStatement(selectSQL);
    ResultSet rs = preparedStatement.executeQuery(selectSQL );
    while (rs.next()) {
        String name = rs.getString(2);  
        System.out.println(name);
        for(int i=0; i<8; i++){
        list[i] = name;
        }
    }
    items = new JComboBox(list);

    chooseQuantity = new JLabel("Choose Quantity:");
    quantity = new JTextField("1");
    choose = new JPanel();
    choose.setLayout(new GridLayout(1,4));
    choose.add(chooseItem);
    choose.add(items);
    choose.add(chooseQuantity);
    choose.add(quantity);
    add(choose);

//other codes

Answer 1

您必须从数据库中像这样选择它。

combobox.addItem(rs.getString("items"));

它从结果集中获取“项目”，并将其放入字符串中，然后将其添加到组合框中。