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Problem with Runtime.getRuntime().exec()

Posted on 2011-03-16
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Last Modified: 2012-05-11
Hi All,

I am using

Process ps=Runtime.getRuntimetime().exe()
int exitvalue=ps.waitfor();

to execute a shell script which communicates with ftp host and prints all the folders and files to a file, I am deploying in WAS CE. If i am not used for some days the application, it is giving NullPointerException. If i restared the server and used the application it is working fine. I am not getting where the problem is can any one help me in getting the solution for this

Thanks in advance
Pavan
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Question by:Gangadhara Melukote
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5 Comments
 
LVL 92

Expert Comment

by:objects
ID: 35145006
can you post the stack trace for the NPE
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Author Comment

by:Gangadhara Melukote
ID: 35145145
It is comming when there is a delay in sending request to that piece of code. At present i dont have the trace but sure it is not returning the Process Object
Thanks
Pavan
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LVL 86

Accepted Solution

by:
CEHJ earned 2000 total points
ID: 35145152
Depending on how you're using Runtime.exec, it might well lock up a process stream which could turn into a NPE further down the line. See

http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html

and

http://technojeeves.com/joomla/index.php/free/52-runtimeexec for a solution if that's a problem
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LVL 92

Expert Comment

by:objects
ID: 35145171
Locking up of runtime exec would not cause an NPE, it would  cause your method to not return.
Let me know when you have more info and I'll have a look at it for you
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LVL 86

Expert Comment

by:CEHJ
ID: 35296506
:)
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