从页面取参数出现空指针异常

Question

        String sid = request.getParameter("sid");
String sname = request.getParameter("sname");
String room_select = request.getParameter("room_select");
String bed_select = request.getParameter("bed_select");
String staytime = request.getParameter("staytime");
System.out.println(staytime);//这里运行后输出的值是null
                SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");
java.util.Date date = null;
try {
date = format.parse(staytime);
} catch (Exception e) {
e.printStackTrace();
//return mapping.findForward("error");
               }finally{
              } 我在页面中输入的是20080901运行后，出现
null
java.lang.NullPointerException
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1215)
at java.text.DateFormat.parse(DateFormat.java:335)
at com.develop.action.DormManageAction.dormIn(DormManageAction.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:619)我在页面中输入的是20080901  
请问：为何会取的日期参数为null，应该怎么写就不会出现异常了，请说详细一点，谢谢
在线等答案，很急

Answer 1

确定你的value是你输入的值吗？好好检查一下，应该是取值不对

Answer 2

直接复制页面中对应日期的input的name到request.getParameter(""); 试试吧
应该是取值的问题

Answer 3

<input type ="text" name="要与request.getPamarater("中一致")">

Answer 4

表单中的name的名必须为staytime才能取到值。差个大小写都不行的。