C# 多线程操作同一个textbox

C# code

        private object sync = new object();        delegate void SetTextCallback(string text);        private void WorkThread()        {            this.ReadText();            this.WorkThread();//为了循环        }        private void ReadText()        {            int a;            lock(sync)            {                a = Convert.ToInt32(textBox1.Text);            }            Thread.Sleep(1000);            a++;            lock(sync)            {                this.SetText(a.ToString());            }        }        private void SetText(string text)        {            // InvokeRequired required compares the thread ID of the            // calling thread to the thread ID of the creating thread.            // If these threads are different, it returns true.            if (this.textBox1.InvokeRequired)            {                SetTextCallback d = new SetTextCallback(SetText);                this.Invoke(d, new object[] { text });            }            else            {                this.textBox1.Text = text;            }        }

这样一段代码用下面代码创建线程

C# code

            Thread t = new Thread(new ThreadStart(WorkThread));            t.Start();

循环指向那段启动代码启动的貌似也只是一个线程.
怎样才能用一个多个线程公用一个 方法? 或者我的代码就不对?

[解决办法]
使用线程数组
Thread t[i]=new Thread(new ThreadStart(WorkThread));
t[i].Start();