org.apache.jasper.JasperException: n must be positive
部分代码如下:  

<%
Connection   conn   =   linejdbc.getopenConnection();
PreparedStatement   p   =   conn.prepareStatement( "select   max(id)   from   tiku ");
ResultSet   rp   =   p.executeQuery();
rp.next();
ResultSet   rs=null;
int   maxid=rp.getInt(1);
int   num;    
int   j=0;
int   i;    


int   randnum[]=new   int[50];
boolean   isexsit=false;

for(num=0;num <50;num++)
{
randnum[num]=0;
}
Random   rand   =   new   Random();
while   (true)
{
isexsit=false;
i   =   rand.nextInt(maxid);
//判断随机数是否重复
for(num=0;num <j;num++)
{
if   (randnum[num]==i)
{
isexsit=true;
break;
}
}
if   (!isexsit)
{
p   =   conn.prepareStatement( "select   *   from   tiku   where   id=? ");
p.setInt(1,i);
rs=p.executeQuery();
if   (rs.next())
{
id=rs.getInt( "id ");
Question   =   rs.getString( "question ");
KeyA   =   rs.getString( "keya ");
KeyB   =   rs.getString( "keyb ");
KeyC   =   rs.getString( "keyc ");
KeyD   =   rs.getString( "keyd ");
Answer   =   rs.getString( "answer ");
%>

错误提示:
type   Exception   report

message  

description   The   server   encountered   an   internal   error   ()   that   prevented   it   from   fulfilling   this   request.

exception  

org.apache.jasper.JasperException:   n   must   be   positive
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.IllegalArgumentException:   n   must   be   positive
java.util.Random.nextInt(Random.java:248)
org.apache.jsp.begin_jsp._jspService(begin_jsp.java:244)
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)


note   The   full   stack   trace   of   the   root   cause   is   available   in   the   Apache   Tomcat/5.0.30   logs.


请高手帮忙解决一下,急!!

------解决方案--------------------
i = rand.nextInt(maxid);

这个方法的参数要是一个整数 maxid打印出来看看 是不是一个负数




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