用 org.junit.Test 测试多线程，遇到 Thread.sleep()就停止而不是睡眠的问题？

如题求问：

测试类如下： public class TestThread {

// @Test

// public void test(){

// MyList myList = new MyList();

// new ThreadA(myList).start();

// new ThreadB(myList).start();

// }

public static void main(String[] args) { MyList myList = new MyList(); new ThreadA(myList).start(); new ThreadB(myList).start(); } 

}

带有 sleep()的类如下： public class ThreadA extends Thread {

protected static Logger logger = LoggerFactory.getLogger(ThreadA.class); private MyList list; public ThreadA(MyList myList){ this.list=myList; } @Override public void run() { try { for (int i = 0; i <10 ; i++) { list.add(); logger.info("添加了"+(i+1)+"个元素"); Thread.sleep(1000); } } catch (Exception e) { e.printStackTrace(); } } 

}

用 @Test 启动测试程序，代码走到 sleep()就回停止，而用 main 启动就正常，这是为什么？