why is return used within if statement in this java code?

Question

so here is the code : i fully understand the code but i am confused why return is used and i do know what return keyword does . i tried running the code without using return but the result was same

import java.util.Scanner;

public class Calculator {

    public static void main (String[] args) {
        Scanner sc= new Scanner(System.in);
        int day, num1, num2;
        System.out.println("* * * * * * * * * * * *" +"\n" + "1. For addition" +"\n" + "2. For Subtraction" +"\n" + "3. For multipication" +"\n" + "4. For division" +"\n" +"* * * * * * * * * * * *");
        System.out.println("Please enter your 1st num");
        num1= sc.nextInt();
        System.out.println("Please enter your 2nd num");
        num2= sc.nextInt();
        System.out.println("Please enter your choice");
        day= sc.nextInt();
        if(day==4 && num2==0) {
            System.out.println("0 is not valid");
            return;
        };
        switch(day) {
            case 1: System.out.println(num1+num2);break;
            case 2: System.out.println(num1-num2);break;
            case 3: System.out.println(num1*num2);break;
            case 4: System.out.println(num1/num2);break;
            default : System.out.println("Wrong input");break;
        }
    }
}

Why is return used at the if condition line ?

If you didn't have the return there based on the conditions day==4 && num2==0 you have a divide by zero condition for case:4 — tronmcp, Nov 11 '14 at 15:06
it will continue, but why dont you try it and see what results you get? use the debugger for this to see what exactly is happening with your code. — Harry, Nov 11 '14 at 15:06
Should this have been closed - the OP doesn't seem to be asking what the `return` keyword does, but rather why the method returns on that condition? — Michael, Nov 11 '14 at 15:11
Agree with commenter, this is not asking what return is used for in a condition but why was it placed there. — tronmcp, Nov 11 '14 at 15:12
i was confused why return was used and was not asking what return does thanks it is clear now — Suraj Bhetwal, Nov 11 '14 at 15:19

score 1 · Answer 1 · answered Nov 11 '14 at 15:02

1

If you read the println, it says "0 is not valid". I am assuming (and you should as well) that the rest of the code cannot run given the input, so the return statement exits the program before it fails.

answered Nov 11 '14 at 15:02

Lawrence Aiello

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score 1 · Answer 2 · edited Nov 11 '14 at 15:07

1

return statement from a void method will terminate the method and in this case, when you call it in public static void main it terminates the whole application.

Your code has a validity check and when the validation fails, your application writes an error message and quits.

edited Nov 11 '14 at 15:07

Luiggi Mendoza

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answered Nov 11 '14 at 15:05

Michal Krasny

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why is return used within if statement in this java code?

2 Answers2