1)现在有T1、T2、T3三个线程，你怎样保证T2在T1执行完后执行，T3在T2执行完后执行？

public class ThreadTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Thread thread1 = new Thread(){
			@Override
			public void run() {
				// TODO Auto-generated method stub
				
				try {
					System.out.println("thread 1 running....");
					sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}finally{
					System.out.println("thread 1 stoped....");
				}
				super.run();
			}
		};
		Thread thread2 = new Thread(){
			@Override
			public void run() {
				// TODO Auto-generated method stub
				
				try {
					System.out.println("thread 2 running....");
					sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}finally{
					System.out.println("thread 2 stoped....");
				}
				super.run();
			}
		};
		Thread thread3 = new Thread(){
			@Override
			public void run() {
				// TODO Auto-generated method stub
				
				try {
					System.out.println("thread 3 running....");
					sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}finally{
					System.out.println("thread 3 stoped....");
				}
				super.run();
			}
		};		
			try {
				thread1.start();
				thread1.join();
				thread2.start();
				thread2.join();
				thread3.start();
				thread3.join();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	
	}

}