code: public JSONArray getJSONArray( String key ) {
        verifyIsNull();
        Object o = get( key );
        if( o != null && o instanceof JSONArray ){
           return (JSONArray) o;
        }
        throw new JSONException( "JSONObject[" + JSONUtils.quote( key ) + "] is not a JSONArray." );
     }
docs: Get the JSONArray value associated with a key.
  
  @param key A key string.
  @return A JSONArray which is the value.
  @throws JSONException if the key is not found or if the value is not a
  JSONArray.