Prevent launching multiple instances of a java application

java runtime executable-jar
Sathish picture Sathish · Aug 12, 2011 · Viewed 20k times · Source

I want to prevent the user from running my java application multiple times in parallel.

To prevent this, I have created a lock file when am opening the application, and delete the lock file when closing the application.

When the application is running, you can not open an another instance of jar. However, if you kill the application through task manager, the window closing event in the application is not triggered and the lock file is not deleted.

How can I make sure the lock file method works or what other mechanism could I use?

Answer

Sap picture Sap · Aug 12, 2011

Similar discussion is at http://www.daniweb.com/software-development/java/threads/83331

Bind a ServerSocket. If it fails to bind then abort the startup. Since a ServerSocket can be bound only once, only single instsances of the program will be able to run.

And before you ask, no. Just because you bind a ServerSocket, does not mean you are open to network traffic. That only comes into effect once the program starts "listening" to the port with accept().

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