一个空指针异常

jsp+servlet+javaBean做的个新闻发布
但是老是报一个空指针异常
数据库内有数据

业务：[code="java"] public LinkedList list() {
String sql = "select * from news order by id desc limit 0,5";
LinkedList list = new LinkedList();
MySQLConnection conn = ConnectionPool.getInstance().getConnection();
ResultSet rs = conn.Query(sql);
System.out.println("this....................");
try {
while (rs.next()) {
News news = new News(rs.getInt(1), rs.getString(2), rs
.getString(3), rs.getString(4), rs.getString(5));
list.add(news);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list;
}[/code]

Servlet:
[code="java"] public void list(HttpServletRequest req, HttpServletResponse res) {
Bnews b = new Bnews();
List list = b.list();
req.setAttribute("list", list);
try {
res.sendRedirect("/jsp/index.jsp");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}[/code]

页面：
[code="java"]

<%
List list = (List) request.getAttribute("list");

                        News news = null;

                        for(int i = 1;i<=list.size();i++)
                        { 
                            news = (News)list.get(i);
                            System.out.println(news.getTitle()+"tttttttt");
                        %>
      <div class="newsinf">
        <div class="inftitle"> <a href="#"><%=news.getTitle()%></a> </div>

[/code]

异常：
[code="java"]type Exception report

message

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

exception

org.apache.jasper.JasperException: Exception in JSP: /jsp/index.jsp:104

101: List list = (List) request.getAttribute("list");
102:

103: News news = null;
104: System.out.println(news.getTitle()+"tttttttt");
105: for(int i = 1;i<=list.size();i++)
106: {
107: news = (News)list.get(i);

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

java.lang.NullPointerException
org.apache.jsp.jsp.index_jsp._jspService(index_jsp.java:147)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

[/code]

[b]问题补充：[/b]
System.out.println(news.getTitle()+"tttttttt");

删除
或者放在
news = (News)list.get(i);

后

再者 news = (News)list.get(i); 已经实例化

Exception：
[code="java"]org.apache.jasper.JasperException: Exception in JSP: /jsp/index.jsp:105

102:

103: News news = new News();
104:

105: for(int i = 1;i<=list.size();i++)
106: {
107: news = (News)list.get(i);
108: System.out.println(news.getTitle()+"tttttttt");

root cause

java.lang.NullPointerException
org.apache.jsp.jsp.index_jsp._jspService(index_jsp.java:148)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

[/code]

org.apache.jasper.JasperException: Exception in JSP: /jsp/index.jsp:105

101: List list = (List)request.getAttribute("list");

102:

103: News news = new News();

104:

105: for(int i = 1;i<=list.size();i++)

106: {

107: news = (News)list.get(i);

108: System.out.println(news.getTitle()+"tttttttt");

list你没有得到，为null，所以105循环时报java.lang.NullPointerException
另外循环是从i=0开始，list.size()-1结束

至于list=null的问题，是由于你用的是重定向，request里保存的值并没有传过到页面上，用转发就好了

101: List list = (List) request.getAttribute("list");

102:

103: News news = null;

104: System.out.println(news.getTitle()+"tttttttt");

105: for(int i = 1;i<=list.size();i++)

106: {

107: news = (News)list.get(i);

很明显没有实例化啊

i<=list.size();貌似应该是i<list.size();，不能=的，你改改吧

看到以下代码：
java部分：
req.setAttribute("list", list);

res.sendRedirect("/jsp/index.jsp");

jsp部分：

List list = (List) request.getAttribute("list");

不报空置针才怪~~

楼主找本书好好看看，区别一下forward和redirect的差异

还有楼主，你的程序后面还会报越界错误

呵呵

错误太多了

res.sendRedirect("/jsp/index.jsp")后， request中的值会清空

站内转发用RequestDispatcher 类