Json to Pojo With Nested Values

JSON to POJO with nested values

You can create Pojo.class as mentioned below

public class pojo {


private Title title;
private String link;
private String type;
private String status;
private String slug;
private String modified_gmt;
private String modified;
private Guid guid;
private String date_gmt;
private String date;
private int id;

public Title getTitle() {
    return title;
}

public void setTitle(Title title) {
    this.title = title;
}

public String getLink() {
    return link;
}

public void setLink(String link) {
    this.link = link;
}

public String getType() {
    return type;
}

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

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public String getSlug() {
    return slug;
}

public void setSlug(String slug) {
    this.slug = slug;
}

public String getModified_gmt() {
    return modified_gmt;
}

public void setModified_gmt(String modified_gmt) {
    this.modified_gmt = modified_gmt;
}

public String getModified() {
    return modified;
}

public void setModified(String modified) {
    this.modified = modified;
}

public Guid getGuid() {
    return guid;
}

public void setGuid(Guid guid) {
    this.guid = guid;
}

public String getDate_gmt() {
    return date_gmt;
}

public void setDate_gmt(String date_gmt) {
    this.date_gmt = date_gmt;
}

public String getDate() {
    return date;
}

public void setDate(String date) {
    this.date = date;
}

public int getId() {
    return id;
}

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

public static class Title {
    private String rendered;

    public String getRendered() {
        return rendered;
    }

    public void setRendered(String rendered) {
        this.rendered = rendered;
    }
}

public static class Guid {
    private String rendered;

    public String getRendered() {
        return rendered;
    }

    public void setRendered(String rendered) {
        this.rendered = rendered;
    }
}
 }

And you can parse list

 try {
        JSONObject jsonObject = new JSONObject("YOUR_RESPOSE");
        JSONArray data = jsonObject.getJSONArray("data");
        Type listType = new TypeToken<ArrayList<pojo>>() {
        }.getType();
        ArrayList<pojo>  list =new Gson().fromJson(data.toString(), listType);

    } catch (JSONException e) {
        e.printStackTrace();
    }

Mapping nested JSON to a Java POJO

Users JSON Object is wrapped in JSON Array which is wrapped in root JSON Object. You need to use collections types:

TypeReference<Map<String, List<Users>>> usersType = new TypeReference<Map<String, List<Users>>>() {};
Map<String, List<Users>> wrappedUsers = mapper.readValue(body, usersType);
List<Users> users = wrappedUsers.values().stream().flatMap(Collection::stream).collect(Collectors.toList());

Or create wrapper class:

class UsersHolder {
    public List<Users> users;

    //getters, setters
}

which you can use as:

UsersHolder wrappedUsers = mapper.readValue(body, UsersHolder.class);
System.out.println(wrappedUsers.users);

Format of POJO for nested JSON?

You can try below code to convert your json string to Pojo object with required fields using Gson library.

Gson gson = new Gson();

JsonArray jsonArray = gson.fromJson (jsonString, JsonElement.class).getAsJsonArray(); // Convert the Json string to JsonArray

JsonObject jsonObj = jsonArray.get(0).getAsJsonObject(); //Get the first element of array and convert it to Json object

Pojo pojo = gson.fromJson(jsonObj.get("data").toString(), Pojo.class); //Get the data property from json object and convert it to Pojo object

or you can define your nested Pojo class to parse it.

class Pojo
{
    private String item1;
    private String item2;

    //Setters and Getters
}

class Data
{
    private Pojo data;

    //Setters and Getters
}

ArrayList<Data> yourArray = new Gson().fromJson(jsonString, new TypeToken<List<Data>>(){}.getType());

EDIT : Try below code to get value1 and value2 using Retrofit.

class Pojo
{
    private String item1;
    private String item2;

    //Setters and Getters
}

class Data
{
    private Pojo data;

    //Setters and Getters
}

class MyData
{
    private ArrayList<Data> dataList;

    //Setters and Getters
}

IService service = restAdapter.create(IService.class);
MyData data = service.getData(); 

ArrayList<Data> list = data.getDataList(); // Retrive arraylist from MyData

Data obj = list.get(0); // Get first element from arraylist

Pojo pojo = obj.getData(); // Get pojo from Data 

Log.e("pojo", pojo.item1 + ", " + pojo.item2);

Nested map of a pojo with Jackson

First, in order to deserialize the nested Error objects containing final fields, it is needed to mark the all-args constructor with @JCreator annotation and use @JsonProperty to set the values properly:

public class Error {
    private final String errcode;
    private final String error;

    @JsonCreator
    public Error(@JsonProperty("errcode") String errcode, @JsonProperty("error") String error) {
        this.errcode = errcode;
        this.error = error;
    }
    // ... getters/toString, etc.
}

Then ObjectMapper::convertValue should be used to read the contents of the map from the JsonNode:

String json = ...; // input JSON string

ObjectMapper om = new ObjectMapper();

JsonNode node = om.readTree(json); // throws JsonProcessingException 

Map<String, Error> errors = om.convertValue(
    node.get("errors"), new TypeReference<Map<String, Error>>(){}
);

errors.forEach((k, v) -> System.out.println(k + " = " + v));
// -> firstError = {errcode='1234', error='The 1. message'}
// -> secondError = {errcode='5678', error='The 2. message'}

Mapping nested JSON values in a Java class

You can club all the supporting classes in one class like below :

@Data
public class Start {
    @JsonProperty("dateTime")
    public Date dateTime;

    public static class Venue {
        @JsonProperty("name")
        public String name;
    }

    @Data
    public static class Classification {
        @JsonProperty("name")
        public String name;
    }

    @Data
    public static class Embedded2 {
        @JsonProperty("venues")
        public List<Venue> venues;
    }

    @Data
    public static class Dates {
        @JsonProperty("start")
        public Start start;
        @JsonProperty("classifications")
        public List<Classification> classifications;
        @JsonProperty("_embedded")
        public Embedded2 _embedded;
    }

    @Data
    public static class Event {
        @JsonProperty("name")
        public String name;
        @JsonProperty("dates")
        public Dates dates;
    }

    @Data
    public static class Embedded {
        @JsonProperty("events")
        public List<Event> events;
    }

    @Data
    public static class Root {
        @JsonProperty("_embedded")
        public Embedded _embedded;
    }
}

You can test (I am using Jackson for deserialization)

create ObjectMapper class and deserialize into a Root class

public class TestJson {
    public static void main(String[] args) {
        ObjectMapper objectMapper = new ObjectMapper();
        try {
            Start.Root root = objectMapper.readValue(new File("C:\\Anurag\\Development\\CodeBase\\demo\\src\\main\\java\\com\\example\\demo\\domain\\testJson\\test.json"), Start.Root.class);
            System.out.println(root);
        } catch (Exception e) {
            e.printStackTrace();
        }


    }
}

-When debugging, you'll notice that our objects have been filled accordingly:
Sample Image

**Changes done as per your requiement **

@Data
public class EventList {

    @Getter
    @JsonProperty("_embedded")
    private Events events;




    @Data
    public static class Venue {
        @JsonProperty("name")
        public String name;
    }

    @Data
    public static class Classification {
        @JsonProperty("name")
        public String name;
    }

    @Data
    public static class Embedded2 {
        @JsonProperty("venues")
        public List<Venue> venues;
    }

    @Data
    public static class Dates {
        @JsonProperty("start")
        public Start start;
        @JsonProperty("classifications")
        public List<Classification> classifications;
        @JsonProperty("_embedded")
        public Embedded2 _embedded;
    }

    @Data
    public static class EventDetails {
        @JsonProperty("name")
        public String name;
        @JsonProperty("dates")
        public Dates dates;
    }

    @Data
    public static class Events {
        @JsonProperty("events")
        public List<EventDetails> eventsList;
    }

    @Data
    public static class Start {
        @JsonProperty("dateTime")
        public Date dateTime;
    }


}

public class TestJson {
    public static void main(String[] args) {
        List<EventList.EventDetails> anyCity = findEventByCity("any city");
        anyCity.stream().forEach(p-> {
            System.out.println(p);
        });

    }

    @SneakyThrows
    static List<EventList.EventDetails> findEventByCity(String city) {
        ObjectMapper objectMapper = new ObjectMapper();
        EventList eventList = objectMapper.readValue(new File("C:\\Anurag\\Development\\CodeBase\\demo\\src\\main\\java\\com\\example\\demo\\domain\\testJson\\test.json"), EventList.class);
        List<EventList.EventDetails> eventsList = eventList.getEvents().getEventsList();
        return eventsList;
    }

    }

ebugging, you'll notice that our objects have been filled accordingly:

Parse JSON nested object to Java POJO with GSON

Not sure how to do it with a List, but this is how to do it with Map:

Map<String, Ping> map = gson.fromJson(json, new TypeToken<Map<String, Ping>>(){}.getType());

Then you can just map.values() if you want all the values.

Json to Pojo With Nested Values