从数据库中选择并在combobox-GUI中显示

Question

我正在尝试从数据库中选择项目的名称，然后将其保存到数组中以便稍后将其添加到JComboBox中，但由于某种原因，它根本不会从数据库中获取它。

以下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

您必须从数据库中选择它。

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

需要＆＃34;项目＆＃34;从你的结果集中，它将它放入一个字符串中，然后将它添加到你的组合框中。

Answer 2

您可以将字符串添加到JComboBox，如下所示：

String item1 = "This is my first item";
String item2 = "This is my second item";

combo.addItem(item1);
combo.addItem(item2);

最后它看起来像这样：