ProgressDialog不显示有关问题

//开始线程读取数据方法
      public void startLoadData() 
      {
          pBar = ProgressDialog.show(this, "请稍后...", "检测查询信息中...", true,  false); 
          Thread GetData = new Thread(new Getdata());   
          GetData.start();   
      }
          public class Getdata implements Runnable {   
                  public void run() {   
                      loadData();
                      messageListener.sendEmptyMessage(TASK_LOOP_COMPLETE);   
                  }   
                     
              }   
      
      private Handler messageListener = new Handler()
      {   
             public void handleMessage(Message msg) 
             {   
                  switch(msg.arg1)
                  {   
                  case TASK_LOOP_COMPLETE:   
                      pBar.dismiss();   
                      //数据读取完成，关闭线程并加载数据
                      SetData();
                      break;   
                         
                  }   
              }   
      };