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Set system property from outside during runtime

Lukas Stephienn
Ranch Hand

Joined: Dec 23, 2005
Posts: 60
Hi all,

Is there any possible way to set system property during runtime of virtual machine from outside world.

For example:
I start some app that will work for a long time. I start it with property -DmyProp=myVal.
While this app is working, I want to change myProp to "otherVal", but I don't want to do it from within app. I want to change that property from OS (or something like that) because I want to have possibility to set it on runtime, and I don't want to modify code of this app.

Can anybody say, is that possible?

Thanks in advance

SCJP 5.0 (91%), SCBCD 1.3 (94%), SCWCD 1.4 (88%)
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

Nope, not possible, not without modifying the app. If you can modify the app, then you'd need to make it listen for input somehow, most likely on a Socket.

[Jess in Action][AskingGoodQuestions]
Peter Chase
Ranch Hand

Joined: Oct 30, 2001
Posts: 1970
How about via debugging interface? These let an external program into the JVM, don't they?

Of course, a production Java program ought to have debugger interfaces turned off (mine do - I hope).

Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.
I agree. Here's the link:
subject: Set system property from outside during runtime
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