这个空指针错误怎么办？高手看看！

Question

org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:356)
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)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.idas.app.framework.core.filter.IdasCharacterEncodingFilter.doFilter(IdasCharacterEncodingFilter.java:37)
com.idas.app.framework.core.filter.IdasCharacterEncodingFilter.doFilter(IdasCharacterEncodingFilter.java:37)
root cause java.lang.NullPointerException
org.apache.jsp.WEB_002dINF.app.publish.jsp.index_jsp._jspInit(index_jsp.java:22)
org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
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)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.idas.app.framework.core.filter.IdasCharacterEncodingFilter.doFilter(IdasCharacterEncodingFilter.java:37)
com.idas.app.framework.core.filter.IdasCharacterEncodingFilter.doFilter(IdasCharacterEncodingFilter.java:37)

Answer 1

package com.idas.app.framework.publish.struts.action;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;import com.idas.app.framework.core.base.action.IdasBaseAction;/**
 * 公告的action
 * 
 * @author ziv zhang
 */
public class AppPublishAction extends IdasBaseAction { /**
 * 进入主页
 * 
 * @param mapping
 * @param actionform
 * @param request
 * @param response
 * @return
 */
public ActionForward doIndex(ActionMapping mapping,
ActionForm actionform, HttpServletRequest request,
HttpServletResponse response) {

return mapping.findForward("index.jsp");
}

/**
 * 进入左边
 * 
 * @param mapping
 * @param actionform
 * @param request
 * @param response
 * @return
 */
public ActionForward doLeft(ActionMapping mapping,
ActionForm actionform, HttpServletRequest request,
HttpServletResponse response) {

return mapping.findForward("left.jsp");
} @Override
protected void onInit() { }
}

Answer 2

和action没有关系，你去到tomcat/wrok/Catalina/localhost/工程名/目录下去找到index_jsp.java这个servlet文件，并打开找到第22行是什么，然后贴出来！

Answer 3

index.jsp  22行空指针错误

Answer 4

java.lang.NullPointerException
org.apache.jsp.WEB_002dINF.app.publish.jsp.index_jsp._jspInit(index_jsp.java:22)
你的jsp出现异常 ，好好检查一线啊

Answer 5

直觉告诉我你的index.jsp
出问题了，但是报的错是index.jsp.java这个文件的，所以你得找到tomcat给你翻译过后的servlet文件，位置在tomcat安装目录下的wrok/Catalina/localhost/工程名下。
你先到这个目录把index.jsp.java打开，找到22行，看看是不是有逻辑错误什么的哈

Answer 6

都不是其他的错误、、错误是因为   jar包重复了。删掉之后就不报空指针错误了。现在好了。

Answer 7

我估计是你的struts.xml里面没有一个return类型的那么是index.jsp的吧。一般struts.xml文件里头的写法是
<result type="success">/index.jsp</result>.然后你在action类中的写法是return SUCCESS;没有index.jsp这个类型，所以会报空指针啊，没有这个对象..