为什么调用另一个类控件改变Text值后无法显示该值，控制台读到的却是最新修改的

有两个类，所有的控件都是创建在类RWForm里的，然后Book类通过继承该类后，通过RWForm rwf = new RWForm();调用到RWForm中的控件，可以改变其中的值，比如lblTest.Text中明明值已经改变了，但窗口上显示的却还是原来的，控制台输出的却是最新修改过的值，莫名啊RWForm主类：
using System;
using System.Threading;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;namespace OSRWForm
{
    public partial class RWForm : Form
    {
        
        public RWForm()
        {
            InitializeComponent();
        }        private void btnRun_Click(object sender, EventArgs e)
        {
            Book book = new Book(5);
            Random random = new Random();            string[] readerNames = { "读者A", "读者B", "读者C" };
            string[] writerNames = { "写者A", "写者B", "写者C" };            Thread[] readerThreads = new Thread[3];
            Thread[] writerThreads = new Thread[3];            for (int i = 0; i < 3; i++)
            {
                Reader reader = new Reader(book, random);
                readerThreads[i] = new Thread(new ThreadStart(reader.Read));
                readerThreads[i].Name = readerNames[i];                Writer writer = new Writer(book, random);
                writerThreads[i] = new Thread(new ThreadStart(writer.Write));
                writerThreads[i].Name = writerNames[i];            }            for (int i = 0; i < 3; i++)
            {
                readerThreads[i].Start();
                writerThreads[i].Start();
            }
        }        private void btnExit_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
    } 
}Book类：
using System;
using System.Threading;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace OSRWForm
{    public class Book : RWForm
    {
        RWForm rwf = new RWForm();
        private int[] pages;
        private bool aWriterWait = false;
        private int readerCount = 0;        private object mutex = new Object(); // 控制对 readerCount 的访问
        private object db = new Object(); // 控制对 pages 的访问
        private object obj = new Object(); // 控制对 aWriterWait 的访问        public Book(int numOfPages)
        {            pages = new int[numOfPages];
        }        public int NumOfPages
        {
            get
            {
                return pages.Length; //常量，无须同步
            }
        }        public int this[int index]
        {            get
            {
                lock (obj)
                {
                    while (aWriterWait)
                    {
                        Monitor.Wait(obj);
                    }
                }                lock (mutex)
                {
                    // readerCount的锁
                    // 检查是否为第一个读者
                    readerCount++;
                    if (readerCount == 1)
                        Monitor.Enter(db);
                }                int valueCopy = pages[index]; // 读取一个数据
                rwf.lblTest.Text = "run0";//测试用的我，可是在窗口上这个文本的值并没有改变
                Console.WriteLine(rwf.lblTest.Text);// 很奇迹的这里输出却是上面修改过的run，为什么窗口上的文本没改变啊？
                rwf.rtxtShow.Text = Thread.CurrentThread.Name + " 读了 第" + (index + 1) + "页，他读到的数据是" + valueCopy;//同样没显示
             //   Console.WriteLine(Thread.CurrentThread.Name + " 读了 第" + (index + 1) + "页，他读到的数据是" + valueCopy);                DisplayContent();                lock (mutex)
                {
                    readerCount--;
                    if (readerCount == 0)
                        Monitor.Exit(db);
                }                return valueCopy;
            }
            set
            {
                lock (obj)
                {
                    aWriterWait = true;
                }                lock (db)
                { // 阻止其他的写者去写书
                    pages[index] = value;                    rwf.rtxtShow.Text = Thread.CurrentThread.Name + "把 " + value + " 写到第" + (index + 1) + "页";
                    Console.WriteLine(Thread.CurrentThread.Name + "把 " + value + " 写到第" + (index + 1) + "页");
                    DisplayContent();
                }                lock (obj)
                {
                    aWriterWait = false;
                    Monitor.PulseAll(obj); // 通知等待的读者
                }
            }
        }        private void DisplayContent()
        {
            Console.WriteLine("{0,-35}", "书的内容是:");
            for (int i = 0; i < pages.Length; i++)
            {
                Console.Write("{0,-9}", pages[i]);
            }
            Console.WriteLine("\r\n");
        }
    }    public class Reader
    {
        private Book book;
        private Random rand;        public Reader(Book b, Random random)
        {
            book = b;
            rand = random;
        }        public void Read()
        {
            for (int i = 0; i < 5; i++)
            {
                int p = rand.Next(0, book.NumOfPages);
                int a = book[p];
                Thread.Sleep(rand.Next(0, 100));
            }
        }
    }
    public class Writer
    {
        private Book book;
        private Random rand;        public Writer(Book b, Random random)
        {
            book = b;
            rand = random;
        }        public void Write()
        {
            for (int i = 0; i < 5; i++)
            {
                int p = rand.Next(0, book.NumOfPages);
                book[p] = rand.Next(50, 100);
                Thread.Sleep(rand.Next(0, 100));
            }
        }
    }}