好奇怪的问题啊,关于java.lang.NullPointerException异常问题]求助
我在jsp里调试下面的页面,要是按住F5不动快速刷新,就会抛出异常java.lang.NullPointerException,如果把
IndexXx ix = new IndexXx();
CssMgr cm = new CssMgr();
xxinfo xx = new xxinfo();
String xxtitle = "";
String xxtjtime = "";
String xxid = "";
int xxsort = 0;
Vector v = new Vector();
这段代码去掉就不会抛出异常,只有加上才会抛出异常,这是什么怪问题阿,又遇到过的吗,困扰很久了,请大家帮我解决一下,不胜感激
list.jsp
<%@ page language="java" contentType="text/html;charset=GBK"%>
<%@ page import="java.io.*" %>
<%@ page import="javaclass.javabean.xxinfo.xxinfostruct" %>
<%@ page import="java.util.*,java.lang.*" %>
<%@ page import="javaclass.javabean.xxinfo.*" %>
<%@ page import="javaclass.javabean.purview.purview" %>
<%
IndexXx ix = new IndexXx();
CssMgr cm = new CssMgr();
xxinfo xx = new xxinfo();
String xxtitle = "";
String xxtjtime = "";
String xxid = "";
int xxsort = 0;
Vector v = new Vector();
try{
ArrayList m1 = new ArrayList();
purview pru = new purview();
ArrayList al = pru.getAllLMName();
}catch(Exception e){
out.println(e.toString());
}
%>
purview.java
public ArrayList getAllLMName()
{
String sql = "select * from rwm_lm order by no";
String lm_name_no="";
ArrayList al = new ArrayList();
try{
RS= Stmt.executeQuery(sql);
while(RS.next())
{
lm_name_no = RS.getString("lanmu")+"|"+RS.getInt("no");
al.add(lm_name_no);
}
}catch(SQLException e)
{
System.out.print(e.getMessage());
}
return al;
}