编译运行问题?

我的程序出现了以下问题.编译时不能通过.谁能帮我解答:

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: Attempted a bean operation on a null object.

at org.apache.jasper.runtime.JspRuntimeLibrary.handleGetProperty(JspRuntimeLibrary.java:511)

at org.apache.jsp.sample1_jsp._jspService(sample1_jsp.java:72)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)

at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549)

at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589)

at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666)

at java.lang.Thread.run(Thread.java:534)