java访问sql数据库查不出货色来

java访问sql数据库查不出东西来
package util;

import DB.DatabaseOperater;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class userUtil 
{
    Connection con = null;
    PreparedStatement sta = null;
    ResultSet rs = null;
    
    public String getUserName(String Uid) 
    {
        String name = "";
        try
        {
            if(con == null)
            {
                DatabaseOperater dbo = new DatabaseOperater();
                dbo.getSqlConnection();
            }
            sta = con.prepareStatement("select name from UserInfo where uid = ?");
            sta.setString(1,Uid);
            rs = sta.executeQuery();
            while(rs.next())
            {
               name = rs.getString(1);
            }
            con.close();
        }
        catch(Exception ex)
        {
            System.err.println(ex.getMessage());
        }
        finally
        {
            return name;
        }        
    }
}

这行代码我实在找不出问题在哪里 确定Uid的值完全可以取到 一切正常 就是访问数据库查不出东西     ResultSet一直没有值 sql语句在sql里看也是正常的
[解决办法]
  if(con == null)
            {
                DatabaseOperater dbo = new DatabaseOperater();
                dbo.getSqlConnection();
            }
改为：  if(con == null)
            {
                DatabaseOperater dbo = new DatabaseOperater();

                con = dbo.getSqlConnection();
            }