title: Toast can't be used in new runnable?
body: <p>as the title,i was used toast in runnable but there is an error
  my code:</p>
  
  <pre><code>public Runnable backgroud=new Runnable(){
  
      public void run() {
          // TODO Auto-generated method stub
          try
          {
              while(!Thread.interrupted())
              {
          String msg="this is a test";
          Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
          Thread.sleep(1000);
              }
          }
          catch(InterruptedException c)
          {
              c.printStackTrace();
          }
      }
  
  };
  </code></pre>