ReentrantLock实现数据一致性

package com.dq;

import java.util.concurrent.locks.ReentrantLock;

public class ThreadTest 
{
	private static int num = 0;
	private static ReentrantLock lock = new ReentrantLock();
	
	public static class T extends Thread 
	{
		@Override
		public void run() 
		{
			for(int index = 0; index < 10000; index++)
			{
				lock.lock();
				try
				{
					num++;
				}
				finally
				{
					lock.unlock();
				}
			}	
		}
	}
	
	public static void main(String[] args) throws Exception
	{
		T t1 = new T();
		T t2 = new T();
		T t3 = new T();
		t1.start();
		t2.start();
		t3.start();
		t1.join();
		t2.join();
		t3.join();
		System.out.println("num is: " + num);
	}

}