java.lang.NullPointerException有关问题，各位大侠帮忙看看，着
日期：2014-05-17 浏览次数：20666 次
java.lang.NullPointerException问题，各位大侠帮忙看看，在线等着
<%@page pageEncoding="GB18030" %>
<%@page import=" java.sql.*" %>
<%@page import=" java.util.*" %>
<%@page import="java.io.*" %>
<%@page import="com.bjsxt.bbs.*" %>
<%!
private void tree(Set<Article> articles,Connection conn,int id,int grade){
String sql = "select * from atticle where pid ="+id;
Statement stmt = DB.createStmt(conn);
ResultSet rs = DB.executeQuery(stmt,sql);
try{
while(rs.next()){
Article a = new Article();
a.setId(rs.getInt("id"));
a.setPid(rs.getInt("pid"));
a.setRootId(rs.getInt("rootid"));
a.setTitle(rs.getString("title"));
a.setLeaf(rs.getInt("isleaf")==0? true : false);
a.setPdate(rs.getTimestamp("pdate"));
a.setGrade(grade);
articles.add(a);
if(!a.isLeaf()){
tree(articles,conn,a.getId(),grade+1);
}
}
}catch(SQLException e){
e.printStackTrace();
}
}
%>
<%
Set<Article> articles = new HashSet<Article>();
Connection conn = DB.getConn();
tree(articles,conn,0,0);
DB.close(conn);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
<HEAD>
<TITLE>论坛: Java语言*初级版</TITLE>
<META content="text/html; charset=UTF-8" http-equiv=content-type>
<LINK
rel=stylesheet type=text/css href="images/style.jsp">
<META name=GENERATOR content="MSHTML 8.00.7600.16535">
</HEAD>
<BODY>
<TABLE border=0 cellSpacing=0 cellPadding=0 width="100%">
<TBODY>
<TR>
<TD width="1%"><A href="http://bbs.chinajavaworld.com/index.jspa">“”<IMG
border=0 alt=JAVA中文世界论坛|JAVA开发者论坛 src="images/header-left.gif"
width=199 height=38></A></TD>
<TD width="98%"><IMG border=0 alt=""
src="images/header-stretch.gif" width="100%" height=38></TD>
<TD width="1%"><IMG border=0 alt="" src="images/header-right.gif"
width=5 height=38></TD>
</TR>
</TBODY>
</TABLE>
<BR>
<BR>
<DIV id=jive-accountbox class=clearfix>
<DL>
<DT>欢迎, 游客 </DT>
<DD><A class=jive-acc-login
href="http://bbs.chinajavaworld.com/login!withRedirect.jspa">登录 / 注册</A> </DD>
<DD><A class=jive-acc-cp
href="http://bbs.chinajavaworld.com/guestsettings!default.jspa">游客设置</A> </DD>
</DL>
</DIV>
<P class=jive-page-title>论坛: Java语言*初级版</P>
<LINK title=RSS
rel=
<%@page pageEncoding="GB18030" %>
<%@page import=" java.sql.*" %>
<%@page import=" java.util.*" %>
<%@page import="java.io.*" %>
<%@page import="com.bjsxt.bbs.*" %>
<%!
private void tree(Set<Article> articles,Connection conn,int id,int grade){
String sql = "select * from atticle where pid ="+id;
Statement stmt = DB.createStmt(conn);
ResultSet rs = DB.executeQuery(stmt,sql);
try{
while(rs.next()){
Article a = new Article();
a.setId(rs.getInt("id"));
a.setPid(rs.getInt("pid"));
a.setRootId(rs.getInt("rootid"));
a.setTitle(rs.getString("title"));
a.setLeaf(rs.getInt("isleaf")==0? true : false);
a.setPdate(rs.getTimestamp("pdate"));
a.setGrade(grade);
articles.add(a);
if(!a.isLeaf()){
tree(articles,conn,a.getId(),grade+1);
}
}
}catch(SQLException e){
e.printStackTrace();
}
}
%>
<%
Set<Article> articles = new HashSet<Article>();
Connection conn = DB.getConn();
tree(articles,conn,0,0);
DB.close(conn);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- saved from url=(0051)http://bbs.chinajavaworld.com/forum.jspa -->
<HTML>
<HEAD>
<TITLE>论坛: Java语言*初级版</TITLE>
<META content="text/html; charset=UTF-8" http-equiv=content-type>
<LINK
rel=stylesheet type=text/css href="images/style.jsp">
<META name=GENERATOR content="MSHTML 8.00.7600.16535">
</HEAD>
<BODY>
<TABLE border=0 cellSpacing=0 cellPadding=0 width="100%">
<TBODY>
<TR>
<TD width="1%"><A href="http://bbs.chinajavaworld.com/index.jspa">“”<IMG
border=0 alt=JAVA中文世界论坛|JAVA开发者论坛 src="images/header-left.gif"
width=199 height=38></A></TD>
<TD width="98%"><IMG border=0 alt=""
src="images/header-stretch.gif" width="100%" height=38></TD>
<TD width="1%"><IMG border=0 alt="" src="images/header-right.gif"
width=5 height=38></TD>
</TR>
</TBODY>
</TABLE>
<BR>
<BR>
<DIV id=jive-accountbox class=clearfix>
<DL>
<DT>欢迎, 游客 </DT>
<DD><A class=jive-acc-login
href="http://bbs.chinajavaworld.com/login!withRedirect.jspa">登录 / 注册</A> </DD>
<DD><A class=jive-acc-cp
href="http://bbs.chinajavaworld.com/guestsettings!default.jspa">游客设置</A> </DD>
</DL>
</DIV>
<P class=jive-page-title>论坛: Java语言*初级版</P>
<LINK title=RSS
rel=
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