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?

Ted Hopp · Accepted Answer · 2012-10-19 00:32:20Z

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, 2012 at 0:32

Ted Hopp

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Comments

Reimeus · Accepted Answer · 2014-11-27 13:56:13Z

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, 2014 at 13:56

answered Oct 19, 2012 at 0:32

Reimeus

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3 Comments

Kalpesh Soni Over a year ago

what if 3 and 4 has some common part, but 4 does some additional stuff

Reimeus Over a year ago

In that case you can let 3 "fall through" to 4. The question here indicates that 3 and 4 have no shared functionality

Ted Hopp Over a year ago

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).

Aravind Yarram · Accepted Answer · 2012-10-19 00:32:44Z

4

Below is the best you can do

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

answered Oct 19, 2012 at 0:32

Aravind Yarram

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Comments

Gene · Accepted Answer · 2012-10-19 00:32:50Z

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, 2012 at 0:32

Gene

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