一、在android中休眠3s鐘有2中方法：

1、SystemClock.sleep(3000);

2、Thread.sleep(3000);

二、通過系統原始碼區別

1、SystemClock.sleep(long ms)原始碼：

1. publicstaticvoid sleep(long ms)  
2.    {  
3.        long start = uptimeMillis();  
4.        long duration = ms;  
5.        boolean interrupted = false;  
6.        do {  
7.            try {  
8.               <span style="color:#ff0000;"> Thread.sleep(duration);</span>  
9.            }  
10.            catch (InterruptedException e) {  
11.                interrupted = true;  
12.            }  
13.            duration = start + ms - uptimeMillis();  
14.        } while (duration > 
    0);  
15.        if (interrupted) {  
16.            // Important: we don't want to quietly eat an interrupt() event,
17.            // so we make sure to re-interrupt the thread so that the next
18.            // call to Thread.sleep() or Object.wait() will be interrupted.
19.            Thread.currentThread().interrupt();  
20.        }  
21.    }  

1. Thread.sleep(long time)原始碼：  

1. publicstaticvoid sleep(long time) throws InterruptedException {  
2.         Thread.sleep(time, 0);  
3.     }  

1. publicstaticvoid sleep(long millis, int nanos) throws InterruptedException {  
2.       VMThread.sleep(millis, nanos);  
3.   }  

1. 最終呼叫到</span>VMThread類原始碼，再呼叫到底層  

1. <pre name="code"class="java"> staticnativevoid sleep (long msec, int nsec) throws InterruptedException;