You did not specify which library you intend to use to represent the JSON object. Usually there are methods to enumerate the properties of the object. For example:

org.json.JSONObject.keys()

returns an iterator of the String names in the object.

public class JsonParsing {

public static Properties properties = null;

public static JSONObject jsonObject = null;

static {
    properties = new Properties();
}

public static void main(String[] args) {

    try {

        JSONParser jsonParser = new JSONParser();

        File file = new File("src/main/java/read.json");

        Object object = jsonParser.parse(new FileReader(file));

        jsonObject = (JSONObject) object;

        parseJson(jsonObject);

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

public static void getArray(Object object2) throws ParseException {

    JSONArray jsonArr = (JSONArray) object2;

    for (int k = 0; k < jsonArr.size(); k++) {

        if (jsonArr.get(k) instanceof JSONObject) {
            parseJson((JSONObject) jsonArr.get(k));
        } else {
            System.out.println(jsonArr.get(k));
        }

    }
}

public static void parseJson(JSONObject jsonObject) throws ParseException {

    Set<Object> set = jsonObject.keySet();
    Iterator<Object> iterator = set.iterator();
    while (iterator.hasNext()) {
        Object obj = iterator.next();
        if (jsonObject.get(obj) instanceof JSONArray) {
            System.out.println(obj.toString());
            getArray(jsonObject.get(obj));
        } else {
            if (jsonObject.get(obj) instanceof JSONObject) {
                parseJson((JSONObject) jsonObject.get(obj));
            } else {
                System.out.println(obj.toString() + "\t"
                        + jsonObject.get(obj));
            }
        }
    }
}}

In contrast to what the accepted answer proposes, the documentation says that for JSONArray() you must use put(value) no add(value).

https://developer.android.com/reference/org/json/JSONArray.html#put(java.lang.Object)

(Android API 19-27. Kotlin 1.2.50)