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();  
    }