How to end program in java

How to end program in java

Ho In this post, we will see how to end program in java.

You can use System.exit(0) to end program in java.

Using System.exit() to end java program

You can use exit() method of System class to end java program.

System.exit() causes Java virtual machine to exit and terminate the current process. You can call System.exit() anywhere in the program, resulting in JVM termination.

As System.exit() is the static method of System class, the compiler does not know what it will do, hence does not give unreachable code error.

If we pass 0 to System.exit() method, it indicates that termination happened successfully and pass this value to operating system.

  • exit(0): It indicates successful end of java program.
  • exit(-1) or exit(1) or exit(any non zero value): It indicates unsuccessful end of java program.

Example to demonstrate System.exit() method

Here is an example:

Output:

Before calling System.exit()

As you can see, it did not print After calling Syste.exit() after calling System.exit() method.

How to end java program in an if statement in java

You can exit program in java based on if statement condition.
Here is an example.

Output:

10
20
30
Terminate the JVM

As you can see, program ended as soon as array element was greater or equals to 40 while iterating. It neither continued the loop nor printed Loop ends here after calling System.exit() method.

Using return to end current method

If you just want to exit from current method, you can use return statement.

return statement stops the execution of current method and return it to calling method. It is a reserved keyword which compiler already knows.

return can end java program if it is the last statement inside main method of class being executed. If you put code after a return statement, compiler will give error about unreachable code.

Here is an example:

Preceding java program will give you compilation error about unreachable code at line number 6.
Another example:
Let’s say you want to write isPrime method to check if number is prime or not. You can call isPrime() method from main method and return true or false based on whether number is prime or not.

Output:

is 17 Prime: true
is 27 Prime: false
is 79 Prime: true

That’s all about how to end program in java.

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