java list与Json转换

/**      * 根据页面用户输入的信息形成 Answer 对象的List      *       * @param answers      * @param question_ids      * @param types      * @return      */      private List<Answer> toAnswerList(String[] studenAnswers, int[] question_ids,              int[] types,int[] scores) {          List<Answer> answerList = new ArrayList<Answer>();          if(studenAnswers!=null && question_ids!= null && types!= null&& scores!= null){              for (int i = 0; i < studenAnswers.length; i++) {                  Answer answer = new Answer();                  String studenAnswer = studenAnswers[i];                  int type = types[i];                  int question_id = question_ids[i];                  int score = scores[i];                  answer.setQuestion_id(question_id);                  answer.setScore(score);                  answer.setStudenAnswer(studenAnswer);                  answer.setType(type);                  answerList.add(answer);              }          }          return answerList;      }      /**      * 将一个json字串转为list      * @param props      * @return      */      public static List<Answer> converAnswerFormString(String answer){          if (answer == null || answer.equals(""))              return new ArrayList();          JSONArray jsonArray = JSONArray.fromObject(answer);          List<Answer> list = (List) JSONArray.toCollection(jsonArray,                  Answer.class);          return list;      }      /**      *       * 将一个 Answer 对象的List 生成Json字串      * 是根据客户端页面用户输入的信息生成的      *       *       */      public String getAnswerString(String[] studenAnswers, int[] question_ids,              int[] types,int[] scores) {          List list = toAnswerList(studenAnswers,  question_ids,                   types, scores);          JSONArray jsonarray = JSONArray.fromObject(list);          return jsonarray.toString();      }