switch case runs a case which is not the case

Question

i am preparung for exams in programming java I. In this exercise I am supposed to run the code by myself and say what comes out. This code is given by the professor of my course. I didn't create this code.

Following is the code:

public class SS13Aufg2 {

    public static void main(String[] args) {

        int a = 1;
        int b = 2;
        while (a < 6) {
            a = a + 2;
            switch (a%3) {
                case 0 : b = a-b;
                case 1 : b = a*b;
            }
        }
    }

}

What I am not able to unterstand, is already in the first time of run through. a = 3 --> a%3 is 0 and case 0 comes out. But after that the program runs case 1 as well. Why? it is not the case.

See also http://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html — Alexis C., Mar 03 '15 at 12:51
This is not my code, it is the code of my prof. I am just supposed to check it out. — kellerprogger, Mar 03 '15 at 13:02

Ruchira Gayan Ranaweera · Answer 1 · 2015-03-03T12:55:37.443

1

You need to use break here. And having a default case is ideal.

switch (a%3) {
    case 0 : b = a-b;
        break;
    case 1 : b = a*b;
        break;
    default:System.out.println("Invalid");          
        break;
}

edited Mar 03 '15 at 12:55

answered Mar 03 '15 at 12:49

Ruchira Gayan Ranaweera

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Use break statement after each case ending as Ruchira mentioned – Saheb Roy Mar 03 '15 at 12:51
You might also want a default case, that raises an error of some kind. – Hunter McMillen Mar 03 '15 at 12:52
@HunterMcMillen yes. it is. – Ruchira Gayan Ranaweera Mar 03 '15 at 12:54
No you understodd me wrong, this code is given by the professor of my course. And I am supposed to run it by myself. I didn't create this code. I am just wondering because it is just doing it the first time. – kellerprogger Mar 03 '15 at 12:59

switch case runs a case which is not the case

1 Answers1