java - JTree 数据未从数据库加载(MySQL)

Question

我正在 MySQL 数据库上创建类别表。我需要列出需要在 JTree 上查看的所有类别，但它未加载。到目前为止我尝试过的代码写在下面。

类别表

+------------+
|id | catname|
+------------+
|1  | book   |
|2  | drink  |
|3  | cake   |
+------------+

public void LoadtTree()
{
   try {
        pst = con.prepareStatement("select * from category");
        rs = pst.executeQuery();     
        DefaultMutableTreeNode categories = new DefaultMutableTreeNode("Categories");
        String currentGroup = null;
        while (rs.next()) {
               String group = rs.getString("catname");
               DefaultMutableTreeNode categorynames= new DefaultMutableTreeNode(rs.getString("catname"));
               categories.add(categorynames);         
        }
    }catch(Exception ex){ex.getMessage();}
}

加载表单时，它仅显示默认节点。如何将数据库值加载到该节点？

连接

 Connection con;
    PreparedStatement pst;
    ResultSet rs;


   public void Connect()
{

    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost/emk", "root","");                     
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(fo.class.getName()).log(Level.SEVERE, null, ex);
    } catch (SQLException ex) {
        Logger.getLogger(fo.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Answer 1

尝试使用 DefaultMutableTreeNode。

这不是我的代码，但尝试看看这个示例:http://www.javaknowledge.info/populate-jtree-from-mysql-database/