Can throw be used instead of break in a switch statement?

Question

Can throw also be used to exit switch statement without using break keyword? Why use a throw instead of break?

switch(number)
{
    case 1:
        throw new RuntimeException("Exception number 1");
    case 2:     
        throw new RuntimeException("Exception number 2"); 
}

Answer 1

There are two cases in which you could use a throw to interrupt the flow of a switch:

1. Flow Control; in general, this is a bad practice - you don't want exceptional behavior deciding where your program decides to go next.

2. Unlikely-but-plausible default case; in case you hit a condition in which reaching the default should be impossible, but happens anyway. Somehow. Miraculously. Or, if you have strict coding standards, which mandate that switch statements have a default case.

   Example:

   public class Test {
       public static enum Example {
           FIRST_CASE,
           SECOND_CASE;
       }
       public void printSwitch(Example theExampleCase) {
           switch(theExampleCase) {
               case FIRST_CASE:
                   System.out.println("First");
                   break;
               case SECOND_CASE:
                   System.out.println("Second");
                   break;
               default:  // should be unreachable!
                   throw new IllegalStateException(
            "Server responded with 724 - This line should be unreachable");
        }
   }