严重: java.lang.NullPointerException

Question

严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
 at org.apache.jsp.userinfo_jsp._jspService(userinfo_jsp.java:212)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:726)
 at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469)
 at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:394)
 at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:311)
 at servlet.RegServlet.doPost(RegServlet.java:103)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
 at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
 at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
 at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
 at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
 at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1437)
 at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 at java.lang.Thread.run(Thread.java:745)
org.apache.jasper.JasperException: An exception occurred processing JSP page /userinfo.jsp at line 75

72:           <td class="content">&nbsp;
73:             <%
74:                String[] favorites = regUser.getFavorites();
75:                for(String f:favorites)
76:                {
77:             %>
78:                 <%=f%> &nbsp;&nbsp;

Stacktrace:
 at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:584)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:481)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:726)
 at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469)
 at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:394)
 at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:311)
 at servlet.RegServlet.doPost(RegServlet.java:103)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
 at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
 at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
 at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
 at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
 at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1437)
 at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
 at org.apache.jsp.userinfo_jsp._jspService(userinfo_jsp.java:212)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
 ... 37 more

怎么解决大神们？

Answer 1

上面说了，空指针异常，一般情况下是，让一个 为空的对象（即不存在的）调用方法。 <%  74:                String[] favorites = regUser.getFavorites(); 75:                for(String f:favorites) 76:                { 77:             %>不知道你上面的对象是否存在，如 regUser

Answer 2

多贴点代码吧