package com.thread;

public class TestSleep {

	public static void main(String[] args) {
		SleepThread st = new SleepThread();
		Thread t1 = new Thread();
		Thread t2 = new Thread();
		t1.start();
		t2.start();
	}
}

class SleepThread implements Runnable{

	@Override
	public void run() {
		for (int i = 0; i < 100; i++) {
			System.out.println(Thread.currentThread().getName()+"-----"+i);
		}
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
	
}

sleep方法源码如下：

 /**
     * Causes the currently executing thread to sleep (temporarily cease
     * execution) for the specified number of milliseconds, subject to
     * the precision and accuracy of system timers and schedulers. The thread
     * does not lose ownership of any monitors.
     *
     * @param  millis
     *         the length of time to sleep in milliseconds
     *
     * @throws  IllegalArgumentException
     *          if the value of {@code millis} is negative
     *
     * @throws  InterruptedException
     *          if any thread has interrupted the current thread. The
     *          <i>interrupted status</i> of the current thread is
     *          cleared when this exception is thrown.
     */
    public static native void sleep(long millis) throws InterruptedException;

    /**
     * Causes the currently executing thread to sleep (temporarily cease
     * execution) for the specified number of milliseconds plus the specified
     * number of nanoseconds, subject to the precision and accuracy of system
     * timers and schedulers. The thread does not lose ownership of any
     * monitors.
     *
     * @param  millis
     *         the length of time to sleep in milliseconds
     *
     * @param  nanos
     *         {@code 0-999999} additional nanoseconds to sleep
     *
     * @throws  IllegalArgumentException
     *          if the value of {@code millis} is negative, or the value of
     *          {@code nanos} is not in the range {@code 0-999999}
     *
     * @throws  InterruptedException
     *          if any thread has interrupted the current thread. The
     *          <i>interrupted status</i> of the current thread is
     *          cleared when this exception is thrown.
     */
    public static void sleep(long millis, int nanos)
    throws InterruptedException {
        if (millis < 0) {
            throw new IllegalArgumentException("timeout value is negative");
        }

        if (nanos < 0 || nanos > 999999) {
            throw new IllegalArgumentException(
                                "nanosecond timeout value out of range");
        }

        if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
            millis++;
        }

        sleep(millis);
    }

解读源码：

这段代码上面的注释意思如下:

sleep(millis)方法用于让当前线程暂停执行指定的毫秒数，取决于系统时间的精确度，当前线程并不会失去锁。

sleep方法是一个静态方法。