<%ResultSet maxfl=conn.mySelect("select * from maxclass ");
while (maxfl.next()){
%>
<tr>
<td width="29%" height="20"><strong><%=maxid%><%=maxfl.getString("classname")%></strong></td>
</tr>
<%
ResultSet minfl=conn.mySelect(" select * from minclass where belong="+maxfl.getInt("id")+"");
while (minfl.next()){
%>
<tr>
<td width="40%" height="20" align="left"><a href="class.asp?id=<%=minfl.getInt("id")%>"><%=minfl.getString("minname")%></a></td>
</tr>
<%
}
}
%>我的意思是每显示一个大分类就把属于该大分类的所有小分类输出来.
出现下列错误:

org.apache.jasper.JasperException
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause

java.lang.NullPointerException
    com.microsoft.jdbc.base.BaseResultSet.cancelPendingUpdates(Unknown Source)
    com.microsoft.jdbc.base.BaseResultSet.next(Unknown Source)
    org.apache.jsp.fl_jsp._jspService(fl_jsp.java:58)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

[此贴子已经被作者于2007-5-25 19:00:33编辑过]

.NullPointerException也就是得不到值，你那有几个&lt;%=?%&gt;地方能确定那得到值吗

原来这样就可以了再定义个实例就可以了