哪种方法会更有效？ （Java Android编程）

Question

In my app I need to change the value of an integer variable . The way I have changed this , like this

  int variable; 

    if (condition) {
        variable= 1;                
    } 
    else if (condition) {
        variable= 2 ;               
    }
   ..........
   ..........
    else {
        variable=3;
    }

Or shpould I declare an array and change the value of variable like this

int variable; 

    if (condition) {
        variable= array[0];                
    } 
    else if (condition) {
        variable= array[1];               
    }
   ..........
   ..........
    else {
        variable=0;
    }

Which the more performance optimized way ? Or both do the same ?

Answer 1

如果梯形图的其他内容过多，则可以使用switch语句来更清楚和快速访问

Answer 2

If your values are constants and simple integers then the first choice is more preferable as that would avoid the overhead of creating arrays and thus saving some memory for you. :)

Also, for switching between the conditions you can consider @henrycharles answer as switch case at times prove more efficient than if-else.

Answer 3

The performance will slightly be worse in the second case I assume (but you will not notice it). I mean you have to bring additional variables to the stack - the array itself. You will need more memory as well to create and keep the array.

But because you have if/else branching, a missed if/else branch will have a bigger impact then array or not-array. Either way I would not worry too much about it, this difference will be in the order of ns.

Of course you call always measure- but micro-benchmarking Java is not always easy.