Android 如何通过服务器响应在列表视图中设置分级栏

我在android中玩，现在我在列表视图中添加了评级条，实际评级条来自服务器响应，然后存储到arraylist中，然后通过dataadapter发送到列表视图。问题是，我不知道如何通过给出的响应来扩大运行时的评级栏，想法？ 这是我的密码：

/**
 * After completing background task Dismiss the progress dialog
 * **/

protected void onPostExecute(String file_url) {
    // dismiss the dialog after getting all score
    pDialog.dismiss();
    // updating UI from Background Thread
    runOnUiThread(new Runnable() {
       public void run() {

          /**
          * Updating parsed JSON data into ListView
          * */

          ListAdapter adapter = new SimpleAdapter( 
               BusinessActivity.this, businessArrayList,
               R.layout.business_list_item, new String[] { TAG_NAME, TAG_EMAIL, TAG_SCORE },
               new int[] { R.id.player_name, R.id.player_email, R.id.player_rating });

               // updating listview
               setListAdapter(adapter);
               }
          });

      }     
  }

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通过将值传递给方法setRating（）可以轻松设置RatingBar值

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设置在我的情况下没有效果

RatingBar rb=(RatingBar)findViewById(R.id.ratingBar);
/*
*After you get response from server, assuming String serverResponse contains the value.
*/
rb.setRating(Float.parseFloat(serverResponse));