Json - java deserialize multiple arrays

Jae
May 5, 2023
247 views
0 votes
2 Answers

I have the following json

{   "users": [
    {
      "id": 1,
      "name": "Ash",
      "email": "[email protected]"
    },
    {
      "id": 2,
      "name": "Gary",
      "email": "[email protected]"
    }],   
"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.

Answers

Add the POJO classes:

public class Example {

    @SerializedName("users")
    @Expose
    private List<User> users;
    @SerializedName("pokemon")
    @Expose
    private List<Pokemon> pokemon;

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

    public List<Pokemon> getPokemon() {
        return pokemon;
    }

    public void setPokemon(List<Pokemon> pokemon) {
        this.pokemon = pokemon;
    }
}


public class Pokemon {

    @SerializedName("userId")
    @Expose
    private Integer userId;
    @SerializedName("name")
    @Expose
    private String name;
    @SerializedName("frontImg")
    @Expose
    private String frontImg;
    @SerializedName("backImg")
    @Expose
    private String backImg;
    @SerializedName("type")
    @Expose
    private String type;
    @SerializedName("hp")
    @Expose
    private Integer hp;
    @SerializedName("id")
    @Expose
    private Integer id;

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getFrontImg() {
        return frontImg;
    }

    public void setFrontImg(String frontImg) {
        this.frontImg = frontImg;
    }

    public String getBackImg() {
        return backImg;
    }

    public void setBackImg(String backImg) {
        this.backImg = backImg;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Integer getHp() {
        return hp;
    }

    public void setHp(Integer hp) {
        this.hp = hp;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

}

public class User {

    @SerializedName("id")
    @Expose
    private Integer id;
    @SerializedName("name")
    @Expose
    private String name;
    @SerializedName("email")
    @Expose
    private String email;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

}

And then call Example e = new Gson().fromJson(json, Example.class);

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":"[email protected]"},{"id":2,"name":"Gary","email":"[email protected]"}],"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" : "[email protected]"
  }, {
    "id" : 2,
    "name" : "Gary",
    "email" : "[email protected]"
  } ],
  "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":"[email protected]"},{"id":2,"name":"Gary","email":"[email protected]"}]
{"id":1,"name":"Ash","email":"[email protected]"}
[{"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"

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Json – java deserialize multiple arrays

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