Avoid Switch statement redundancy when multiple Cases do the same thing?

Question

I have multiple cases in a switch that do the same thing, like so: (this is written in Java)

 case 1:
     aMethod();
     break;
 case 2:
     aMethod();
     break;
 case 3:
     aMethod();
     break;
 case 4:
     anotherMethod();
     break;

Is there any way I can combine cases 1, 2 and 3 into one case, since they all call the same method?

score 25 · Answer 1 · answered Oct 19 '12 at 00:32

25

case 1:
case 2:
case 3:
    aMethod();
    break;
case 4:
    anotherMethod();
    break;

This works because when it happens to be case 1 (for instance), it falls through to case 2 (no break statement), which then falls through to case 3.

answered Oct 19 '12 at 00:32

Ted Hopp

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Reimeus · Answer 2 · 2014-11-27T13:56:13.013

7

Sure, you can allow case clause sections for 1 & 2 to 'fall through' to clause 3 and then break out of the switch statement after that:

case 1:
case 2:
case 3:
     aMethod();
     break;
case 4:
     anotherMethod();
     break;

edited Nov 27 '14 at 13:56

answered Oct 19 '12 at 00:32

Reimeus

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what if 3 and 4 has some common part, but 4 does some additional stuff – Kalpesh Soni Aug 30 '13 at 22:33
In that case you can let 3 "fall through" to 4. The question here indicates that 3 and 4 have no shared functionality – Reimeus Aug 30 '13 at 22:46
Well, no, you can't let 3 fall through to 4. In that case, anything done for case 4 would always get done for case 3 as well and it would be 3 that would be doing the extra stuff (before falling through). Using a `switch`, you can only do the additional stuff _before_ the common stuff. If you want other logic, you need to use other control structures (or `if` statements nested inside switch cases, which I find ugly). – Ted Hopp Dec 30 '15 at 07:17

score 4 · Answer 3 · answered Oct 19 '12 at 00:32

4

Below is the best you can do

case 1:
case 2:
case 3:
     aMethod();
     break;
 case 4:
     anotherMethod();
     break;

answered Oct 19 '12 at 00:32

Aravind Yarram

78,777
46
231
327

score 4 · Answer 4 · answered Oct 19 '12 at 00:32

4

It's called the "fall through" pattern:

case 1:  // fall through
case 2:  // fall through
case 3: 
   aMethod(); 
   break; 
case 4: 
   anotherMethod(); 
   break;

answered Oct 19 '12 at 00:32

Gene

46,253
4
58
96

Avoid Switch statement redundancy when multiple Cases do the same thing?

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