可以 wait()、notify() 实现；也可以使用发令枪 CountDownLatch 实现。
CountDownLatch 实现较简单，如下：
package constxiong.interview;import java.util.concurrent.CountDownLatch;/** * 测试同时启动多个线程 * @author ConstXiong */public class TestCountDownLatch {private static CountDownLatch cld = new CountDownLatch(10);public static void main(String[] args) {for (int i = 0; i <10; i++) {Thread t = new Thread(new Runnable() {public void run() {try {cld.await();//将线程阻塞在此，等待所有线程都调用完start()方法，一起执行} catch (InterruptedException e) {e.printStackTrace();}System.out.println(Thread.currentThread().getName() + ":" + System.currentTimeMillis());}});t.start();cld.countDown();}}}