線程執行的順序 等線程執行完再執行下一個線程

[csharp] 
Thread tr = null; 
delegate void Methinvoker(); 
private void btSeInfo_Click(object sender, EventArgs e) 
{ 
 
    tr = new Thread(new ThreadStart(SeleInfo)); 
    tr.IsBackground = true; 
    //  tr.SetApartmentState(ApartmentState.STA);  
    tr.Start(); 
 
 
    Thread tr1 = new Thread(new ThreadStart(StartThreadCaiji)); 
    tr1.Start(); 
} 
private void StartThreadCaiji() 
{ 
    tr.Join(); 
    Methinvoker meth = new Methinvoker(MessSeInfo); 
    this.BeginInvoke(meth); 
} 
private void MessSeInfo() 
{ 
 
    //Monitor.Enter(obj);  
    // Monitor.Wait(obj);  
    MessageBox.Show("數據采集完成,成功采集記錄總數:【" + caiji.ToString() + "】條\n 其中紅色訊號燈表示通訊錯誤，綠色表示提取成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information); 
    pbLoad.Value = 0; 
    tbpg.Text = ""; 
    caiji = 0; 
    btStopSelect.Enabled = false; 
    //   Monitor.Exit(obj);  
} 

        Thread tr = null;
        delegate void Methinvoker();
        private void btSeInfo_Click(object sender, EventArgs e)
        {

            tr = new Thread(new ThreadStart(SeleInfo));
            tr.IsBackground = true;
            //  tr.SetApartmentState(ApartmentState.STA);
            tr.Start();

            Thread tr1 = new Thread(new ThreadStart(StartThreadCaiji));
            tr1.Start();
        }
        private void StartThreadCaiji()
        {
            tr.Join();
            Methinvoker meth = new Methinvoker(MessSeInfo);
            this.BeginInvoke(meth);
        }
        private void MessSeInfo()
        {

            //Monitor.Enter(obj);
            // Monitor.Wait(obj);
            MessageBox.Show("數據采集完成,成功采集記錄總數:【" + caiji.ToString() + "】條\n 其中紅色訊號燈表示通訊錯誤，綠色表示提取成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            pbLoad.Value = 0;
            tbpg.Text = "";
            caiji = 0;
            btStopSelect.Enabled = false;
            //   Monitor.Exit(obj);
        }