The performance between the 'normal' operation and the 'shift' operation.

First, I gonna post my test result with some code:

 1 //test the peformance of the <normal operation> and the <shift operation>.
 2 class ShiftOperation 
 3 {
 4     public static void main(String[] args) 
 5     {
 6         long startTime1 = System.nanoTime();
 7         for(long i = 0; i < 10000000000L; i++){
 8             int temp = 128 * 128;
 9         }
10         long endTime1 = System.nanoTime();
11         System.out.println("elapse = " + (endTime1 - startTime1) + " ns");
12         //outputs:elapse = 13265249285 ns
13 
14         long startTime2 = System.nanoTime();
15         for(long i = 0; i < 10000000000L; i++){
16             int temp = 128 << 8;
17         }
18         long endTime2 = System.nanoTime();
19         System.out.println("elapse = " + (endTime2 - startTime2) + " ns");
20         //outputs:elapse = 12723663971 ns
21     }
22 }

The below screen shot shows the simple steps of the operations between the two.

posted @ 2014-03-03 15:50  wonkju  阅读(214)  评论(0)    收藏  举报