join(), 当前线程暂停, 等待指定的线程执行结束后, 当前线程再继续
* join(int), 可以等待指定的毫秒之后继续
	* 
			final Thread t1 = new Thread() {
				public void run() {
					for(int i = 0; i < 50; i++) {
						System.out.println(getName() + "...aaaaaaaaaaaaaaaaaaaaaa");
						try {
							Thread.sleep(10);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
				}
			};
			
			Thread t2 = new Thread() {
				public void run() {
					for(int i = 0; i < 50; i++) {
						if(i == 2) {
							try {
								//t1.join();						//插队,加入
								t1.join(30);						//加入,有固定的时间,过了固定时间,继续交替执行
								Thread.sleep(10);
							} catch (InterruptedException e) {
								
								e.printStackTrace();
							}
						}
						System.out.println(getName() + "...bb");
					
					}
				}
			};
			
			t1.start();
			t2.start();