JSP与servlet的空指针问题，请帮忙看看

helloworld3213 2010-03-25 07:38:56

HTTP Status 500 -

type Exception report

message

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

exception

org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
cn.com.jobedu.blog.PostEditBlogServlet.doPost(PostEditBlogServlet.java:55)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

java.lang.NullPointerException
org.apache.jsp.editBlog_jsp._jspService(editBlog_jsp.java:83)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
cn.com.jobedu.blog.PostEditBlogServlet.doPost(PostEditBlogServlet.java:55)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.
Apache Tomcat/6.0.20

我看了编译的83行是： out.print(blog.getId());
我的editBlog.jsp页面中这样写的：<input type="hidden" name="id" value="<%=blog.getId()%>"></input>

并且查看源文件的时候可以读到value的值，请各位看看这是怎么回事谢谢

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