Difference in System. exit(0) , System.exit(-1), System.exit(1 ) in Java

java system.exit
giri picture giri · Mar 12, 2010 · Viewed 427.6k times · Source

I'd like to know the difference between the following in Java

System.exit(0);
System.exit(-1);
System.exit(1);

When do I have to use the above code appropriately?

Answer

Jack picture Jack · Mar 12, 2010

The parameter of exit should qualify if the execution of the program went good or bad. It's a sort of heredity from older programming languages where it's useful to know if something went wrong and what went wrong.

Exit code is

  • 0 when execution went fine;
  • 1, -1, whatever != 0 when some error occurred, you can use different values for different kind of errors.

If I'm correct exit codes used to be just positive numbers (I mean in UNIX) and according to range:

  • 1-127 are user defined codes (so generated by calling exit(n))
  • 128-255 are codes generated by termination due to different unix signals like SIGSEGV or SIGTERM

But I don't think you should care while coding on Java, it's just a bit of information. It's useful if you plan to make your programs interact with standard tools.

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