Return value from a Java code
The return value of a Java application is not the return value of it's main method, because a Java application doesn't necessarily end when it's main method has finished execution.
Instead the JVM ends when no more non-daemon threads are running or when System.exit() is called.
And System.exit() is also the only way to specify the return value: the argument passed to System.exit() will be used as the return value of the JVM process on most OS.
So ending your main() method with this:
System.exit(0);will ensure two things:
- that your Java application really exits when the end of
mainis reached and - that the return value of the JVM process is 0
Java programs do not return an exit code back to the operating system by returning a value from main, as is done in C and C++. You can exit the program and specify the exit code by calling System.exit(code);, for example:
// Returns exit code 2 to the operating systemSystem.exit(2);