Why should I always use break with a switch ?

 switch (foo) { case 0: case 1: bar(); break; default: break; }

For example, here, both at 0 and at 1, the bar() method is called?

  • Clarify the question - "Why I should always use," but in the example you don't use break with "0". - 0xdb
  • I did not write there to show that without break, if foo == 0, then the bar () method is called, I want to know why? - Varuzhan Stepanyan
  • 3
    Yes, but the question is "Why do I always have to ." You should not always use break, you can use it. Probably you wanted to ask - When should I use it? - 0xdb

3 answers 3

The switch is made in such a way that when the required element is found, it “fails”. For example, you have a 10-digit switch from 1 to 10. When you transmit 5 for comparison, the switch will be compared in order with 1,2,3,4,5. At this point, the values ​​will coincide further, if no break is indicated, the code will be executed, in the 5,6,7,8,9,10 case. You have no break in the case 0, so your method is executed. add a break and everything will be ok.

    Perhaps it will be clearer if we consider the "case x:" as the "entry point", upon entering which you "fall" through a set of commands. The command "break" - "stops" your "fall" (if necessary). Here is a good example.

     public class SwitchExample { public static void main(String[] args) { byte x = (byte)(Math.random()*10); //случайный этаж System.out.println("Выпал из окна " + x + " этажа"); x--;//падаем через этажи, расположенные ниже switch (x) { case 9:System.out.println("Пролетаю 9 этаж"); case 8:System.out.println("Пролетаю 8 этаж"); case 7:System.out.println("Пролетаю 7 этаж"); case 6:System.out.println("Пролетаю 6 этаж"); case 5:System.out.println("Пролетаю 5 этаж"); System.out.println("зацепились - ниже не падаем"); break; case 4:System.out.println("Пролетаю 4 этаж"); case 3:System.out.println("Пролетаю 3 этаж"); case 2:System.out.println("Пролетаю 2 этаж"); case 1:System.out.println("Пролетаю 1 этаж"); case 0:System.out.println("На земле"); break;//ниже земли не падаем default:System.out.println("Странно"); } } }

      Why should I always use break with a switch statement?

      Obviously, to tell the compiler where the processing of each case ends.