When to use system.exit(0)?

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

Can anyboby please explain the use of system.exit(0)?
What will happen internaly when we call this method especially the argument value? 0,1,2,3.. etc

In addition to the information provided by the answers, the following needs to be added: **do not call `System.exit`** at all unless you **specifically** need the Java process to report an error code. That use case is **exceedingly rare** and most probably you would be calling `System.exit` for no good reason. `System.exit` is a very raw, low-level, and unsafe way to end your program. It `stop`s all threads in the middle of whatever they were doing, giving them no chance to clean up. I have yet to write my first production-quality app that would make use of this call. — Marko Topolnik, Oct 15 '12 at 10:10

score 1 · Answer 1 · edited Feb 09 '18 at 15:56

1

System.exit will ask the VM process to stop, and the code returned will be the code given in parameter. Common codes are: 0 for success, 1 to 127 for error, 128-255 is used by Unix and mapped to signals.

edited Feb 09 '18 at 15:56

Ondra Žižka

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answered Oct 15 '12 at 10:06

mkhelif

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score 0 · Answer 2 · answered Oct 15 '12 at 10:05

System.exit(int) shuts down the JVM, providing an 'exit code' of 0.

The exit code is the JVM process's return value.

Usually in Unix systems, an exit code of 0 indicates a normal shutdown, and anything that is not zero indicates the shutdown was caused by an error.

See Wikipedia for more information:

http://en.wikipedia.org/wiki/Exit_status

score 0 · Answer 3 · answered Oct 15 '12 at 10:06

The input to System.exit is your error code. A value of 0 means normal exit. A non zero number will indicate abnormal termination. This number can be up to you. Perhaps if you want to exit if you cannot read a file you could use error code =1, if you cannot read from a socket it could be error code = 2.

System.exit will terminate the VM and so your program.

A typical example could be below. If the runMyApp throws an exception where you want to cause the program to exit.

public static void main(String... args) {
   try {
      runMyApp();
   } catch (Exception e) {
      System.exit(1);
   }
}

When to use system.exit(0)?

3 Answers3

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