how to shutdown a system when it is not used. if a system is not used for a 2 minutes of time like not even used keyboard or mouse or any other applications in system. that system should be shut down. how to make this one possible.
The Process class allows you to run commands for windows/any OS from java below is snippet
Process proc = runtime.exec("shutdown -s");
System.exit(0);
Place the above code in your logic and rest how you want that to invoke depends on your logic the way you want.
Note : Here I am guessing by system you mean your OS. if you mean just application then just System.exit(0); would suffice.
EDIT :
As asked by OP to check the idle time, I think you need to implement event listeners mostly mouse and keyboard. Below are some helpful links to which will help you implement it in your program:
Java mouse motion anywhere on screen
How can I listen for key presses (within Java Swing) across all components?
Approach for above is have a timer just when you record an event from keyboard or mouse reset the timer else shutdown.