Variable value switch cases in Java

I'm looking to make a switch where 5 of the cases are functionally identical, but then th开发者_StackOverflow中文版ere will be other unique cases. Is there a way to list a case value that handles 5 different values? Thanks

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You can compound the labels in the switch

switch (variable) {
  case 'a': case 'b' : case 'c' : case 'd' :
     do something;
     break;
  case 'e': case 'f' :
     do something else
     break;
  default:
     do something;
}

Thinking of a switch as a jump to a label (possibly coupled with a jump (the break) to the end) will help. That means the switch

switch (variable) {
  case 'a': case 'b' : case 'c' : case 'd' :
     do something;
     // note that there's no break here.
  case 'e': case 'f' :
     do something else
     break;
  default:
     do something;
}

will "do something" and "do something else" for 'a', 'b', 'c', and 'd'; while it will only "do something else" for 'e' and 'f'. Finally if it's not any of the above it hits the default block of "do something".

---

switch (value) {
case 1:
case 2:
case 3:
case 4:
    doSomethingIdentical();
    break;
case 5:
    doSomethingDifferent();
    break;
default:
    break;
}

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This is very easy to do. Instead of just having one case value that handles all 5 different values, let the 5 case values fall through to each other, like so:

switch(value)
{
    case 1:
    case 2:
        //case 1 and 2 will both result in this code being executed
        doSomething();
        break;
    case 3:
        doSomethingElse();
        break;
}

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As long as you don't put a break; on a switch it will fall through to the next statement.

In that way, you can have something like this:

String value(int val) {
    String out = "";
    switch(val) {
    case 0:
        out = "case 0";
        break;
    case 1:
        out = "case 1";
        break;
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
        out = "case 2, 3, 4, 5 or 6";
        break;
    case 7:
        out = "case 7";
        break;
    }
    return out;
}

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Yes, just use a switch like this:

switch(v) {

   case 1:
   case 2:
   case 3:
       identicFunctionality();
       break;
   case 4:
       other01();
       break;
   case 5:
       other02();
       break;
   default:
       _default();
}

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As of Java 12 I believe it is supported. Check out JEP 354. I have never used the syntax but I think it would run like this for your case.

switch (day) {
    case 1, 2, 3, 4, 5    -> System.out.println("1-5");
    case 7                -> System.out.println(7);
    case 8                -> System.out.println(8);
    case 9                -> System.out.println(9);
}

on a related note JEP 325 is also cool.