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

问题

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?

回答1:

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.

回答2:

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;

回答3:

Below is the best you can do

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

回答4:

It's called the "fall through" pattern:

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

来源：https://stackoverflow.com/questions/12965738/avoid-switch-statement-redundancy-when-multiple-cases-do-the-same-thing