How to access nested elements of a JSON array using only GSON with Java

No idea why you thought you'd need a new JsonParser when the JSON has already been parsed.

Just so we can all see what you're parsing, here is a part of it:

{  "page": 1,  "per_page": 10,  "total": 99,  "total_pages": 10,  "data": [    {      "id": 1,      "timestamp": 1565637002408,      "diagnosis": {        "id": 3,        "name": "Pulmonary embolism",        "severity": 4      },      "vitals": {        "bloodPressureDiastole": 154,        "bloodPressureSystole": 91,        "pulse": 125,        "breathingRate": 32,        "bodyTemperature": 100      },      "doctor": {        "id": 2,        "name": "Dr Arnold Bullock"      },      "userId": 2,      "userName": "Bob Martin",      "userDob": "14-09-1989",      "meta": {        "height": 174,        "weight": 172      }    },    ...  ]}

Java is an Object-Oriented language. Use it! Create a class for store the data values, then have a single List<Data>.

List<Data> dataList = new ArrayList<>();

You already got to iterate the data, so let's start there.

Don't lookup the object in the array multiple times. Bad for performance, and bad for the readability of the code.

JsonArray dataArray = convertedObject.getAsJsonArray("data");for (JsonElement dataElem : dataArray) {    System.out.println(dataElem);    JsonObject dataObj = dataElem.getAsJsonObject();    int id = dataObj.get("id").getAsInt();    long timestamp = dataObj.get("timestamp").getAsLong();    String userDob = dataObj.get("userDob").getAsString();    // Now for the good stuff    JsonObject vitals = dataObj.getAsJsonObject("vitals");    int bpDiastole = vitals.get("bloodPressureDiastole").getAsInt();    int bpSystole = vitals.get("bloodPressureSystole").getAsInt();    Data data = new Data();    data.setId(id);    data.setTimestamp(timestamp);    data.setBirthDate(userDob);    data.setBpd(bpDiastole);    data.setBps(bpSystole);    dataList.add(data);}

where the Data class is:

public class Data {    private int id;    private long timestamp;    private String birthDate;    private int bpDiastole;    private int bpSystole;    // Getters and setter here}

    JsonObject jsonObject = gson.fromJson(answer, JsonObject.class);    jsonObject.getAsJsonArray("data").get(0).getAsJsonObject().getAsJsonObject("vitals");

Will return you JsonObject you need. All you need is to go through the array by for loop (.get(i)).