null pointer exception

[abyinsydney]

folks
how do you catch null pointer exception.ie.


what is the hierarchy for catching null pointer exception

in try castch block


aby

 

[sedj]

try {
  //somestuff
} catch (NullPointerException npe) {
  //do something
  npe.printStackTrace(System.err);
}

or :

try {
  //somestuff
} catch (Exception e) {
  //do something
  e.printStackTrace(System.err);
}

 

[abyinsydney]

sedj
i'm trying to catch null pointer exception but unable to catch it any comments

 

[sedj]

have you tried :

try {
//somestuff
} catch (Exception e) {
//do something
e.printStackTrace(System.err);
}
??

 

[abyinsydney]

i'M GETTING TH EFOLOWING ERROR WHEN EXECUTING THE RESULT SET AND THE ERROR IS GETTING PRINTIED ON MY SCREEN I DO NOT WANT IT TOBE PRINTED ON MY SCREEN BUT CATCH IT THRO SYSTEM.OUT .PRINTLN

i HAVE TRIED ALL EXCEPTIONS BUT NOTHINGS SEEMS TO WORK


PLEASE HELP SEDJ
ABY
500 Internal Server Error
/archiving/archiving/jsp/transactions10.jsp:

java.lang.NullPointerException
at jrun__archiving__jsp__transactions12ejsp20._jspService(jrun__archiving__jsp__transactions12ejsp20.java:421)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.jsp.JRunPageContext.forward(../jsp/JRunPageContext.java:298)
at jrun__archiving__jsp__transactions112ejsp21._jspService(jrun__archiving__jsp__transactions112ejsp21.java:117)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.jsp.JRunPageContext.forward(../jsp/JRunPageContext.java:298)
at jrun__archiving__jsp__transactions102ejsp21._jspService(jrun__archiving__jsp__transactions102ejsp21.java:113)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1552)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1542)
at allaire.jrun.servlet.JvmContext.dispatch(../servlet/JvmContext.java:364)
at allaire.jrun.http.WebEndpoint.run(../http/WebEndpoint.java:115)
at allaire.jrun.ThreadPool.run(../ThreadPool.java:272)
at allaire.jrun.WorkerThread.run(../WorkerThread.java:75)

 

[vulcand4]

try {
//somestuff
} catch (Exception e) {
//do something
e.printStackTrace(System.out);
}

using System.out as the parameter to the printStackTrace() method will cause the stack trace to print in standard output as if you had used System.out.println();

 

[abyinsydney]

ploy guy

The exception is getting printed on the screen i do not want itto be printed on the screen it occupies the whole page i want to catchit .there are no excptions method to catch it i have tried all the posssibilities any suggestions


aby

 

[abyinsydney]

greetings folkshow do i accomplish the fact that when your result set returns null from the data base you redirect your page to a different jsp

i HAVE TRIED <jsp:forward page="login.jsp"/>

it does not work .could any body helpme inthis

i'm using my sql and jsp

aby

 

[venur]

Hi,

<%
if(null == resultSet){
%>
<jsp:forward page="login.jsp"/>
<%
}
%>

Is this what u tried ?

Cheers
Venu

 

[abyinsydney]

yes venu that what i have tried but i'm not getting redirected to login.jsp.get the folowing error

h1>500 Internal Server Error</h1>
<PRE>
<B>/archiving/archiving/jsp/transactions10.jsp:</B>

java.lang.NullPointerException
at jrun__archiving__jsp__transactions12ejsp20._jspService(jrun__archiving__jsp__transactions12ejsp20.java:319)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.jsp.JRunPageContext.forward(../jsp/JRunPageContext.java:298)
at jrun__archiving__jsp__transactions112ejsp21._jspService(jrun__archiving__jsp__transactions112ejsp21.java:120)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.jsp.JRunPageContext.forward(../jsp/JRunPageContext.java:298)
at jrun__archiving__jsp__transactions102ejsp21._jspService(jrun__archiving__jsp__transactions102ejsp21.java:132)
at allaire.jrun.jsp.HttpJSPServlet.service(../jsp/HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(../jsp/JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1416)
at allaire.jrun.session.JRunSessionService.service(../session/JRunSessionService.java:1082)
at allaire.jrun.servlet.JRunSE.runServlet(../servlet/JRunSE.java:1270)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(../servlet/JRunRequestDispatcher.java:89)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1552)
at allaire.jrun.servlet.JRunSE.service(../servlet/JRunSE.java:1542)
at allaire.jrun.servlet.JvmContext.dispatch(../servlet/JvmContext.java:364)
at allaire.jrun.http.WebEndpoint.run(../http/WebEndpoint.java:115)
at allaire.jrun.ThreadPool.run(../ThreadPool.java:272)
at allaire.jrun.WorkerThread.run(../WorkerThread.java:75)

</PRE>

 

[sedj]

Just add some debug like System.err.println("here") to see where you are going wrong ... its how everybody else works out where their NPE's are ...

 

[abyinsydney]

sedj
i've debugged the problem my problem is if the result set returns a null value.i'm not able to redirect it to a different page.

if it does not returns a null value the code works fine.

does the resultset has to be printed then redirected to a different page ???


aby

 

[sedj]

Try something like this :

...
ResultSet rs = ...

boolean hasData = rs.next();

if (hasData) {
  // do something
} else {
  // redirect
}