奇怪问题，请高手指点，Illegal operation on empty result set.

Question

本帖最后由 lxkj123 于 2010-01-28 11:14:26 编辑

Answer 1

Illegal operation on empty result set你的数据集返回的是null值
1） 检查你的sql语句 是否正确
2） 确实无数据返回 要加异常处理

Answer 2

看Exception就知道，是对空数据集的操作是非法的

Answer 3

源程序对应：
  public static MaplePet loadFromDb(int itemid, byte position, int petid) {
        try {
            MaplePet ret = new MaplePet(itemid, position, petid);
            Connection con = DatabaseConnection.getConnection(); // Get a connection to the database
            PreparedStatement ps = con.prepareStatement("SELECT * FROM pets WHERE petid = ?"); // Get pet details..
            ps.setInt(1, petid);
            ResultSet rs = ps.executeQuery();
            if(rs.next());
            {
            ret.setName(rs.getString("name"));
            ret.setCloseness(rs.getInt("closeness"));
            ret.setLevel(rs.getInt("level"));
            ret.setFullness(rs.getInt("fullness"));
            }
            rs.close();
            ps.close();
            return ret;
        } catch (SQLException ex) {
            Logger.getLogger(MaplePet.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
    }

Answer 4

//有可能rs为空
if(rs.next()); 

Answer 5

if(rs.next()); //这里这么有个分号？
if(rs != null && rs.next()){}

Answer 6

SELECT * FROM pets WHERE petid = id
去数据库先查一查数据在说，你数据库没数据吧

Answer 7

if(rs.next())
            { 
            ret.setName(rs.getString("name")); 
            ret.setCloseness(rs.getInt("closeness")); 
            ret.setLevel(rs.getInt("level")); 
            ret.setFullness(rs.getInt("fullness")); 
            } 
重新运行试试，保证执行的是重新编译过的class。

Answer 8

  rs.close(); 放到finally语句试试

Answer 9

if(rs.next()); 
            { 
            ret.setName(rs.getString("name")); 
            ret.setCloseness(rs.getInt("closeness")); 
            ret.setLevel(rs.getInt("level")); 
            ret.setFullness(rs.getInt("fullness")); 
            } else{
return null;
}            return ret; 
        } catch (SQLException ex) { 
            Logger.getLogger(MaplePet.class.getName()).log(Level.SEVERE, null, ex); 
            return null; 
        }finnal{
                   rs.close(); 
            ps.close(); 
}