一、在android中休眠3s钟有2中方法：

1、SystemClock.sleep(3000);

2、Thread.sleep(3000);

二、通过系统源码区别

1、SystemClock.sleep(long ms)源码：

public static void sleep(long ms)
    {
        long start = uptimeMillis();
        long duration = ms;
        boolean interrupted = false;
        do {
            try {
               <span style="color:#ff0000;"> Thread.sleep(duration);</span>
            }
            catch (InterruptedException e) {
                interrupted = true;
            }
            duration = start + ms - uptimeMillis();
        } while (duration > 0);
        
        if (interrupted) {
            // Important: we don't want to quietly eat an interrupt() event,
            // so we make sure to re-interrupt the thread so that the next
            // call to Thread.sleep() or Object.wait() will be interrupted.
            Thread.currentThread().interrupt();
        }
    }

有源码可知SystemClock.sleep还是调用 Thread.sleep

Thread.sleep(long time)源码：

public static void sleep(long time) throws InterruptedException {
        Thread.sleep(time, 0);
    }

public static void sleep(long millis, int nanos) throws InterruptedException {
        VMThread.sleep(millis, nanos);
    }

最终调用到</span>VMThread类源码，再调用到底层

<pre name="code" class="java"> static native void sleep (long msec, int nsec) throws InterruptedException;

3、所以在android开发者建议使用 Thread.sleep(long time)方法