面试题：C#编码实现两个线程对数组变量分别加1减1，居然没有做出来

 private static object lockObj = new object();//定义锁
      private static object lockObj2 = new object();//定义锁
        static int[] i = new int[] { 0 };//数组
        public static void Main()
        {
        //开启两个线程
            Thread thread = new Thread(new ThreadStart(Threadaddition));
            thread.Start();
            Thread thread2 = new Thread(new ThreadStart(Threadsub));
            thread2.Start();

            Console.WriteLine(i[0]);
        }
        private static void Threadaddition()
        {
            try
            {
                while (true)
                {
                    lock(lockObj)//加锁
                    {
                    Thread.Sleep(1000);
                    i[0] = i[0] + 1;
                    }
                }
            }
            catch (Exception ee)
            {
            }
        }
        private static void Threadsub()
        {
            try
            {
                while (true)
                {
                    lock (lockObj2)//加锁
                    {
                        Thread.Sleep(1000);
                        i[0] = i[0] - 1;
                    }
                }
            }
            catch (Exception ee)
            {
            }
           
        }