CODEWITHSUNDEEP
jspdate
Dinesh Mishra
Dinesh Mishra

Reputation: 87

Difference between 2 dates throws java.lang.NullPointerException

I am new to JSP and I need help for calculating difference between 2 dates in seconds, which gets the date input from a form in the "yyyy-MM-dd" format. But while I compile it I get the error. Please help me in correcting it.

Error:

java.lang.NullPointerException
    at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1380)
    at java.text.DateFormat.parse(DateFormat.java:355)
    at org.apache.jsp.datediff2_jsp._jspService(datediff2_jsp.java:105)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)

My code is as follows:

<%@ page language ="java" import="java.sql.*,java.text.SimpleDateFormat, java.util.Date,java.text.*, java.util.Calendar" %>
<html>
<body bgcolor="pink">
<form method="post">
<input  name="T1" value="2013-07-01"/> 
<input  name="T2" value="2013-07-31"/>
<input type="submit" value="Submit" name="B1">
</form>

<%

String dStart = request.getParameter("T1");
String dStop = request.getParameter("T2");

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Date d1 = null;
Date d2 = null;

try {
d1 = format.parse(dStart);
d2 = format.parse(dStop);

out.print(d1);

long difference = d2.getTime() - d1.getTime();

long seconds = difference / 1000;

out.print(seconds);

} catch (Exception e) {
e.printStackTrace();
}
%>

</body>
</html>

Upvotes: 1

Views: 2599

Answers (1)

Ravi K Thapliyal
Ravi K Thapliyal

Reputation: 51711

Since, this is a self-submitting form, the first time the page loads T1 and T2 would not be set. So, use an if block to check for nulls and skip the date arithmetic if parameters are not set. JSP would load fine then.

<%
  String dStart = request.getParameter("T1");
  String dStop = request.getParameter("T2");

  if (dStart != null && dStop != null) {
    // rest of the code
  }
%>

Once you submit the dates, your date arithmetic code would get executed as well.

Upvotes: 1

Related Questions