java deserialize multiple arrays

Question

I have the following json

{   "users": [
    {
      "id": 1,
      "name": "Ash",
      "email": "ashketchum@kanto.com"
    },
    {
      "id": 2,
      "name": "Gary",
      "email": "garyoak@kanto.com"
    }],   
"pokemon": [
    {
      "userId": 1,
      "name": "Ember",
      "frontImg": "/images/pokemon/local-mon/ember/front.png",
      "backImg": "/images/pokemon/local-mon/ember/back.png",
      "type": "fire",
      "hp": 100,
      "id": 1
    },
    {
      "userId": 1,
      "name": "Draggy",
      "frontImg": "/images/pokemon/local-mon/dragon/front.png",
      "backImg": "/images/pokemon/local-mon/dragon/back.png",
      "type": "dragon",
      "hp": 100,
      "id": 2
    }   ] }

How could I deserialize this into a single object or array containing both the users array of data and the pokemon array of data in Java? Preferably in gson but I'm not opposed to changing libraries.

Answer 1

I suggest using Jackson to read JSON strings into Java Object without defining a suitable class.

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import java.io.IOException;

public class JavaApplication {
    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        mapper.enable(SerializationFeature.INDENT_OUTPUT);

        String json = "{\"users\":[{\"id\":1,\"name\":\"Ash\",\"email\":\"ashketchum@kanto.com\"},{\"id\":2,\"name\":\"Gary\",\"email\":\"garyoak@kanto.com\"}],\"pokemon\":[{\"userId\":1,\"name\":\"Ember\",\"frontImg\":\"/images/pokemon/local-mon/ember/front.png\",\"backImg\":\"/images/pokemon/local-mon/ember/back.png\",\"type\":\"fire\",\"hp\":100,\"id\":1},{\"userId\":1,\"name\":\"Draggy\",\"frontImg\":\"/images/pokemon/local-mon/dragon/front.png\",\"backImg\":\"/images/pokemon/local-mon/dragon/back.png\",\"type\":\"dragon\",\"hp\":100,\"id\":2}]}";
        JsonNode data = mapper.readTree(json);

        System.out.println(mapper.writeValueAsString(data));
        System.out.println(data.get("users"));
        System.out.println(data.get("users").get(0));
        System.out.println(data.get("pokemon"));
        System.out.println(data.get("pokemon").get(0).get("name"));
    }
}

The output will be:

{
  "users" : [ {
    "id" : 1,
    "name" : "Ash",
    "email" : "ashketchum@kanto.com"
  }, {
    "id" : 2,
    "name" : "Gary",
    "email" : "garyoak@kanto.com"
  } ],
  "pokemon" : [ {
    "userId" : 1,
    "name" : "Ember",
    "frontImg" : "/images/pokemon/local-mon/ember/front.png",
    "backImg" : "/images/pokemon/local-mon/ember/back.png",
    "type" : "fire",
    "hp" : 100,
    "id" : 1
  }, {
    "userId" : 1,
    "name" : "Draggy",
    "frontImg" : "/images/pokemon/local-mon/dragon/front.png",
    "backImg" : "/images/pokemon/local-mon/dragon/back.png",
    "type" : "dragon",
    "hp" : 100,
    "id" : 2
  } ]
}
[{"id":1,"name":"Ash","email":"ashketchum@kanto.com"},{"id":2,"name":"Gary","email":"garyoak@kanto.com"}]
{"id":1,"name":"Ash","email":"ashketchum@kanto.com"}
[{"userId":1,"name":"Ember","frontImg":"/images/pokemon/local-mon/ember/front.png","backImg":"/images/pokemon/local-mon/ember/back.png","type":"fire","hp":100,"id":1},{"userId":1,"name":"Draggy","frontImg":"/images/pokemon/local-mon/dragon/front.png","backImg":"/images/pokemon/local-mon/dragon/back.png","type":"dragon","hp":100,"id":2}]
"Ember"