用三个线程按顺序循环打印 abc 三个字母

package test;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class Test {
	public static void main(String[] args) {
		Test t = new Test();
		ExecutorService es = Executors.newCachedThreadPool();
		List<String> list = new ArrayList<String>();
		list.add("a");
		list.add("b");
		list.add("c");
		Lock lock = t.new Lock(list);
		lock.list.forEach(e -> es.execute(t.new MyPrint(lock, e, 100)));
		es.shutdown();
	}
	class Lock {
		List<String> list;
		String str;
		Lock(List<String> list) {
			this.list = list;
			this.str = list.get(0);
		}
	}
	class MyPrint implements Runnable {
		String str;
		Lock lock;
		int loopNum;
		final int num;
		MyPrint(Lock lock, String str, int loopNum) {
			this.lock = lock;
			this.str = str;
			this.loopNum = loopNum;
			num = lock.list.indexOf(str);
		}
		@Override
		public void () {
			synchronized (lock) {
				while (true) {
					if (lock.str.equals(str)) {
						System.out.println(str);
						lock.str = (num + 1 == lock.list.size() ? lock.list.get(0) : lock.list.get(num + 1));
						lock.notifyAll();
						if (loopNum-- == 0)
							break;
					} else {
						try {
							lock.wait();
						} catch (InterruptedException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
					}
				}
			}
		}
	}
}