如何转换ArrayList <object> 转换为字符串，反之亦然

Question

I want to convert my ArrayList<object> to a JSON String and back to ArrayList<object>

But I really don't know how to do that :

Something like :

Convert
ArrayList<data> arrayData = new ArrayList<data>();
 JSONObject retObject = new JSONObject();
    retObject.put("data", new JSONArray(arrayData ));

    Return convert

idk...

Answer 1

You can consider using a JSON library like Google's Gson library to store and retrieve objects as JSON strings. This is a lightweight library, well regarded and popular. It would be an ideal solution in your case with minimal work required. eg,

// How to store JSON string

Gson gson = new Gson();
// This can be any object. Does not have to be an arraylist.

String json = gson.toJson(myAppsArr);

// How to retrieve your Java object back from the string

Gson gson = new Gson();

DataObject obj = gson.fromJson(arrayString, ArrayList.class);

Answer 2

Using Jackson:

ObjectMapper mapper = new ObjectMapper();
String listAsJson = mapper.writeValueAsString(oldList);
List<Object> newList= mapper.readValue(listAsJson ,new TypeReference<List<Object>>() {});

Answer 3

ArrayList<Product> arrayData = new ArrayList<Product>();
Gson gson = new Gson();

convert list to json object

String jsonCartList = gson.toJson(cartList);

convert json to your list

List<Product> prodList = gson.fromJson(jsonCartList, Product.class);