class强制转换使用try catch

OnArticleSelectedListener mListener;  
  ...  
  @Override  
  public void onAttach(Activity activity){  
      super.onAttach(activity);  
      try{  
          mListener =(OnArticleSelectedListener)activity;  
      }catch(ClassCastException e){  
          throw new ClassCastException(activity.toString()+"must implement OnArticleSelectedListener");  
      }  
  }