Conversion between JSON's String string and Java's List object

On the front end:
1. If json is converted from List object, you can directly traverse json and read data.
2. If you need to convert the front-end List object to json and send it to the backend, param is the ajax parameter, then the conversion is as follows:

var jsonStr = JSON.stringify(list);
var param= {};
param.jsonStr=jsonStr;

In the backend:
1. Convert String to List (str to list)

List<T> list = new ArrayList<T>();
JSONArray jsonArray = JSONArray.fromObject(str);//把String转换为json
list = JSONArray.toList(jsonArray,t);//这里的t是Class<T>

2. Convert List to json

JSONArray json = JSONArray.fromObject(object);
String str = json.toString();//把json转换为String

eg:
1. Form a List of Answer objects based on the information input by the page user

/**
  * @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;
 }

2. Generate a Json string from a List of Answer objects based on the customer Generated from the information input by the user on the end page

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();
}

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