Question

一段jsp代码 已经运行成功了，为什么还报空指针异常，而且 不知道哪里有空指针异常

这是异常：java.lang.NullPointerException
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:212)
at org.apache.struts.util.RequestUtils.createActionForm(RequestUtils.java:292)
at org.apache.struts.util.RequestUtils.createActionForm(RequestUtils.java:191)
at org.apache.struts.action.RequestProcessor.processActionForm(RequestProcessor.java:331)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:202)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at dlufl.filter.UserFilter.doFilter(UserFilter.java:68)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at dlufl.filter.SetCharacterEncoding.doFilter(SetCharacterEncoding.java:32)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)

Answer 1

FormBeanConfig.java:212 这行应该有变量值为NULL
JAVA里即使运行成功，但是只要你运行中有变量是NULL，那么它就会报这个错，你找找看
我估计你是初始的时候没给那个变量赋值，后来才赋的值，假如你变量是a，那么
加一句if(a!=null){ 运行你的代码 }

Answer 2

z3638048z 正解