多线程（至少三个线程）分别打印A、B、C，要求按ABC的顺序循环打印10次。

看到网上一道题，三个线程按顺序打印A、B、C循环10次，于是自己按几种方法也写了一下：

一、用线程池、Lock锁和condition(Object 监视器方法的使用)组合使用实现：

package multithread;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class TestABCThread {
	private Lock lock = new ReentrantLock();
	private Condition condition = lock.newCondition();
	private int count;

	public static void main(String[] args) {
		ExecutorService executorService = Executors.newFixedThreadPool(3);
		TestABCThread abc = new TestABCThread();
		for (int i = 0; i < 10; i++) {
			executorService.execute(abc.new Run("AAAAAAAAAAAAAAAA", 1));
			executorService.execute(abc.new Run("BBBBBBBBBBBBBBBBB", 2));
			executorService.execute(abc.new Run("CCCCCCCCCCCCCCcCC", 3));
		}
		executorService.shutdown();
	}

	class Run implements Runnable {
		private String _name = "";
		private int _threadNum;

		public Run(String name, int threadNum) {
			_name = name;
			_threadNum = threadNum;
		}

		@Override
		public void run() {
			lock.lock();
			try {
				while (true) {
					if (count % 3 == _threadNum - 1) {
						System.out.println("Thread-Name:" + _name);
						count++;
						condition.signalAll();
						break;
					} else {
						try {
							condition.await();
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
				}
			} finally {
				lock.unlock();
			}
		}
	}
}

二、用线程池、synchronized关键字和Object 监视器方法组合实现（实现跟第一种大同小异）：

package multithread;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TestABCThread2 {
	private Object lock = new Object();
	private int count;

	public static void main(String[] args) {
		ExecutorService executorService = Executors.newFixedThreadPool(3);
		TestABCThread2 abc = new TestABCThread2();
		for (int i = 0; i < 10; i++) {
			executorService.execute(abc.new Run("AAAAAAAAAAAAAAAA", 1));
			executorService.execute(abc.new Run("BBBBBBBBBBBBBBBBB", 2));
			executorService.execute(abc.new Run("CCCCCCCCCCCCCCcCC", 3));
		}
		executorService.shutdown();
	}

	class Run implements Runnable {
		private String _name = "";
		private int _threadNum;

		public Run(String name, int threadNum) {
			_name = name;
			_threadNum = threadNum;
		}

		@Override
		public void run() {
			synchronized (lock) {
				while (true) {
					if (count % 3 == _threadNum - 1) {
						System.out.println("Thread-Name:" + _name);
						count++;
						lock.notifyAll();
						break;
					} else {
						try {
							lock.wait();
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
				}
			}
		}
	}
}

三、不用线程池，synchronized关键字和Object 监视器方法组合实现（Lock和Condition差不多就不写了）：

package multithread;

public class TestABCThread3 {
	private Object lock = new Object();
	private int count;

	public static void main(String[] args) {
		TestABCThread3 abc = new TestABCThread3();
		new Thread(abc.new Run("AAAAAAAAAAAAAAAA", 1)).start();
		new Thread(abc.new Run("BBBBBBBBBBBBBBBBB", 2)).start();
		new Thread(abc.new Run("CCCCCCCCCCCCCCcCC", 3)).start();
	}

	class Run implements Runnable {
		private String _name = "";
		private int _threadNum;

		public Run(String name, int threadNum) {
			_name = name;
			_threadNum = threadNum;
		}

		@Override
		public void run() {
			for (int i = 0; i < 10; i++) {
				synchronized (lock) {
					while (true) {
						if (count % 3 == _threadNum - 1) {
							System.out.println("Count:" + i + ",Thread-Name:"
									+ _name);
							count++;
							lock.notifyAll();
							break;
						} else {
							try {
								lock.wait();
							} catch (InterruptedException e) {
								e.printStackTrace();
							}
						}
					}
				}
			}
		}
	}
}