Gson with complicated Json Android Studio

Question

My Json file is

{"code":0,"datas":[{"id":0,"target_id":0},{"id":1,"target_id":0
}................]}

And what I wrote is.. // String data; // data has the Json as String

JsonParser jsonParser = new JsonParser();
JsonObject object = (JsonObject) jsonParser.parse(data);
JsonArray memberArray = (JsonArray) object.get("datas");
JsonObject object1= (JsonObject) memberArray.get(0);
dataParsed = object1.get("id").getAsString(); 

// wanted print 1

And it's not working.. As I guess it's something different with normal Json on Internet. I thought "code" : 0 is the problem I want to know how to seperate this json code / data and get id and target id String

Answer 1

Here you can do the following code for obtaining id and target_id values from your json:

JsonParser jsonParser = new JsonParser();
JsonObject object = (JsonObject) jsonParser.parse(new String(Files.readAllBytes(Paths.get("test.json"))));
JsonArray memberArray = (JsonArray) object.get("datas");

for (JsonElement jsonElement : memberArray) {
    System.out.println(
            String.format("Id : %d TId: %d", 
                    jsonElement.getAsJsonObject().get("id").getAsInt(), 
                    jsonElement.getAsJsonObject().get("target_id").getAsInt()));
}

Output is:

Id : 0 TId: 0
Id : 1 TId: 0

Answer 2

Your JSON contains an integer ("code") plus an array. the array itself contains a number of JSON objects. First, extract a JSON object and an array, then extract JSON objects from the array. My solution for storing these data is based on object-oriented programming. Create a Java object with two variables called DataObject . An integer for "code" and a list of another Java object called IdPair for storing "id" and "target_id" . First, define the classes. IdPair object class:

public class IdPair {
    int id;
    int target_id;

    public int getId() {
        return id;
    }

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

    public int getTarget_id() {
        return target_id;
    }

    public void setTarget_id(int target_id) {
        this.target_id = target_id;
    }
}

DataObject class:

public class DataObject {

    private int code;
    private List<IdPair> idPairs;

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public List<IdPair> getIdPairs() {
        return idPairs;
    }

    public void setIdPairs(List<IdPair> idPairs) {
        this.idPairs = idPairs;
    }
}

then start extracting data from your json:

DataObject dataObject = new dataObject(); // init object

JSONObject jsonObject = new JSONObject(data); // whole json is an object! (data is your json)

int code = jsonObject.optInt("code"); // get code from main json

dataObject.setCode(code); // set code to our object

List<IdPair> pairs = new ArrayList<>(); // init list of id pairs

JSONArray datas = jsonObject.optJSONArray("datas"); // get json array from main json

IdPair pair = null; // define idPairs object 

for (int i=0; i<datas.length() ; i++){ // jasonArray loop

    JSONObject object = new JSONObject(datas(i)); // each jsonObject in the jsonArray

    pair = new IdPair();// init idPair

    int id = object.optInt("id"); // get the object id 
    int targetId = object.optInt("target_id"); // get the object target_id 

    // set values to our object
    pair.setId(id); 
    pair.setTarget_id(targetId);
    //add object to list
    pairs.add(pair);
}
// your dataObject is now filled with JSON data

Note: this is a general solution. For example, you could use a HashMap instead of IdPair object.