Nested JSON objects within JSON array

Question

I'm trying to parse the nested JSON object within the JSON array. I'm not sure how to go about accessing all the objects and the Keys and Values within the nested JSON objects in a generic way.

 {
 "flights": [
 {
 "ident": "AWI4207",
 "faFlightID": "AWI4207-1505297520-schedule-0000",
 "origin": {
 "code": "KORF",
 "city": "Norfolk, VA",
 "alternate_ident": "",
 "airport_name": "Norfolk Intl"
 },
 "destination": {
 "code": "KPHL",
 "city": "Philadelphia, PA",
 "alternate_ident": "",
 "airport_name": "Philadelphia Intl"
 },
 "filed_ete": 2400,
 "filed_departure_time": {
 "epoch": 1505470320,
 "tz": "EDT",
 "dow": "Friday",
 "time": "06:12AM",
 "date": "15/09/2017",
 "localtime": 1505455920
 },
 }
 ]
 }

Here's what i've done so far.

JSONParser parser = new JSONParser();
JSONObject object = (JSONObject) parser.parse(new FileReader("PathToFile.json"));
JSONArray jsonArray = (JSONArray) object.get("flights");
Iterator<Object> eventJSONIterator = jsonArray.iterator();
while (eventJSONIterator.hasNext()) {
 JSONObject jsonEvent = (JSONObject) eventJSONIterator.next();
 System.out.println(jsonEvent.toString());
}

I'm able to access the objects but not the sub-objects separately. Is there a way to iterate through the object in the "flights" array and know somehow if i've encountered a JSON Object (e.g. "origin") again and loop inside it? Rather than doing the following

JSONObject mainObject = (JSONObject) jsonArray.get(0);
JSONObject origin = (JSONObject) mainObject.get("origin");
JSONObject destination = (JSONObject) mainObject.get("destination");
JSONObject filed_departure_time = (JSONObject) mainObject.get("filed_departure_time");

Also, i want to access the keys as origin_code, origin_city and destination_code, destination_city etc. so as to know which object it belonged to.

• trincot: I suppose this is Java. Please tag your question as such.

Answer 1

You can do this

JSONParser parser = new JSONParser();
 JSONObject object = (JSONObject) parser.parse(new FileReader("PathToFile.json"));
 JSONArray jsonArray = (JSONArray) object.get("flights");
 for(int i=0;i<jsonArray.size();i++){
 JSONObject flightJSON = jsonArray.getJSONObject(i);
 JSONObject origin = flightJSON.getJSONObject("origin");
 String code = origin.get("code");
 String city = origin.get("city");
 String alternate_ident = origin.get("alternate_ident");
 String airport_name = origin.get("airport_name");
 //Similaryly for these
 JSONObject destination = flightJSON.getJSONObject("destination");
 JSONObject filed_departure_time = flightJSON.getJSONObject("filed_departure_time");
 }

You need to know the structure to parse it but if you don't know whether it is array,object or other entities, you can try

 Object object = json.get("key");
 if (object instanceof JSONArray) {
 // JSONObject
 jsonArray = (JSONArray)object;
 }else if (object instanceof JSONObject) {
 // JSONArray
 jsonObject = (JSONObject)object;
 }else {
 // String or Integer etc.
 }

• Alohamora153: jsonArray.length() inside the for loop shows me error for some reason. "The method length() is undefined for the type JSONArray"
• Shriyansh Gautam: have you imported org.json.JSONArray for JSONArray?
• Shriyansh Gautam: see the updated answer jsonArray.size() for your case
• Alohamora153: Yes. I was using org.json.simple.JSONArray. It worked after making a few adjustments. But i still want to know if there's any way of identifying a JSON object within JSON object without having to look at the JSON array.
• Shriyansh Gautam: if you don't know the structure then there is no what for rest you can see the updated answer