How to parse nested JSON from Map<String, Object>

Question

I am using the below to map a json response to a Map

 Map<String, Object> apiResponse = restTemplate.postForObject("https://maps.googleapis.com/maps/api/geocode/json?address="+defaultLocation+"&key="+API_KEY, httpEntity, Map.class, Collections.EMPTY_MAP);

I can use the below to output the entire JSON to a string

 String jsonResponse = apiResponse.get("results").toString();

However, what I want to get is a nested value which is results->geometry->location

I have tried a number of solution with JSONArrays, JSONObjects, Substring but can't get them to work.

Response JSON:

{
 "results" : [
 {
 "address_components" : [
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "locality", "political" ]
 },
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "administrative_area_level_2", "political" ]
 },
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "administrative_area_level_1", "political" ]
 },
 {
 "long_name" : "New Zealand",
 "short_name" : "NZ",
 "types" : [ "country", "political" ]
 }
 ],
 "formatted_address" : "Auckland, New Zealand",
 "geometry" : {
 "bounds" : {
 "northeast" : {
 "lat" : -36.660571,
 "lng" : 175.287137
 },
 "southwest" : {
 "lat" : -37.065475,
 "lng" : 174.4438016
 }
 },
 "location" : {
 "lat" : -36.8484597,
 "lng" : 174.7633315
 },
 "location_type" : "APPROXIMATE",
 "viewport" : {
 "northeast" : {
 "lat" : -36.660571,
 "lng" : 175.287137
 },
 "southwest" : {
 "lat" : -37.065475,
 "lng" : 174.4438016
 }
 }
 },
 "place_id" : "ChIJ--acWvtHDW0RF5miQ2HvAAU",
 "types" : [ "locality", "political" ]
 },
 {
 "address_components" : [
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "political", "sublocality", "sublocality_level_1" ]
 },
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "locality", "political" ]
 },
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "administrative_area_level_2", "political" ]
 },
 {
 "long_name" : "Auckland",
 "short_name" : "Auckland",
 "types" : [ "administrative_area_level_1", "political" ]
 },
 {
 "long_name" : "New Zealand",
 "short_name" : "NZ",
 "types" : [ "country", "political" ]
 },
 {
 "long_name" : "1010",
 "short_name" : "1010",
 "types" : [ "postal_code" ]
 }
 ],
 "formatted_address" : "Auckland, 1010, New Zealand",
 "geometry" : {
 "bounds" : {
 "northeast" : {
 "lat" : -36.8364659,
 "lng" : 174.7838398
 },
 "southwest" : {
 "lat" : -36.8621041,
 "lng" : 174.7503805
 }
 },
 "location" : {
 "lat" : -36.8484597,
 "lng" : 174.7633315
 },
 "location_type" : "APPROXIMATE",
 "viewport" : {
 "northeast" : {
 "lat" : -36.8364659,
 "lng" : 174.7838398
 },
 "southwest" : {
 "lat" : -36.8621041,
 "lng" : 174.7503805
 }
 }
 },
 "place_id" : "ChIJuZqpSPtHDW0R4LOiQ2HvAAU",
 "types" : [ "political", "sublocality", "sublocality_level_1" ]
 }
 ],
 "status" : "OK"
}

Any help would be greatly appreciated.

• Pavneet_Singh: please share your json output and the code what u have tried
• Yonkee: @PavneetSingh I have added the response JSON. The code has come and gone, so I can add what I have tried. Im really interested in the best approach if you have one?
• Yoram: check this answer. It is what you are looking for. stackoverflow.com/questions/40407198/…
• v1shnu: You should convert the object which you get from apiResponse.get(results) to an JSONObject. In that way , you will access to all the elements inside it..
• Yonkee: @ViChU How do I get nested values from a JSONObject? I tried but no luck?

Answer 1

JSONObject obj=new JSONObject(jsonresult);
// get result array
JSONArray resultsarray= obj.getJSONArray("results"); 
for (int i=0;i<resultsarray.length(),i++){
 // get Objects using index
 JSONObject jsonobject= results.getJSONObject(i);
 // get geometry object
 JSONObject geometry= jsonobject.getJSONObject("geometry");
 // get location object from geometry
 JSONObject location= geometry.getJSONObject("location");
 // get location values from location object
 double lat = location.optDouble("lat",0.0);
 double long = location.optDouble("lng",0.0);
 }

About optDouble

public double optDouble(String key, double defaultValue) {

Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

• Yonkee: Which JSONObject are you using? Mine doesn't support getJSONArray
• Pavneet_Singh: @Yonkee i am using org.json.JSONObject
• Yonkee: Boom, its working. I think I was using the wrong JSON library during my investigation. Thanks for your help.
• Pavneet_Singh: @Yonkee i am glad that it worked for you :) happy coding

Answer 2

Ideally, you would like to access the properties with the same native notation like you would do in JS. Something like this:

String url = "https://maps.googleapis.com/maps/api/geocode/json?address=" + address;
String responseStr = fetch(url);
JsonHelper response = JsonHelper.forString(responseStr);
String status = (String) response.getValue("status");
if(status != null && status.equals("OK")) {
 lat = (Double) response.getValue("results[0].geometry.location.lat"); 
 lng = (Double) response.getValue("results[0].geometry.location.lng");
}

The following JsonHelper class code (taken from jello-framework) lets you do exactly that.

package jello.common;
import java.util.List;
import com.google.gson.Gson;
import java.util.AbstractMap;
public class JsonHelper {
 private Object json;
 public JsonHelper(String jsonString) {
 Gson g = new Gson();
 json = g.fromJson(jsonString, Object.class);
 }
 public static JsonHelper forString(String jsonString) {
 return new JsonHelper(jsonString);
 }
 @SuppressWarnings("unchecked")
 public Object getValue(String path) {
 Object value = json;
 String [] elements = path.split("\\.");
 for(String element : elements) {
 String ename = element.split("\\[")[0];
 if(AbstractMap.class.isAssignableFrom(value.getClass())) {
 value = ( (AbstractMap<String, Object>) value).get(ename);
 if(element.contains("[")) {
 if(List.class.isAssignableFrom(value.getClass())) {
 Integer index = Integer.valueOf(element.substring(element.indexOf("[")+1, element.indexOf("]")) );
 value = ((List<Object>) value).get(index);
 }
 else {
 return null;
 }
 }
 }
 else {
 return null;
 }
 }
 return value;
 }
}

• Yonkee: I have implemented this, but still unsure how to get nested values? JSONHelper jsonHelper = new JSONHelper(apiResponse.toString())

Answer 3

Use jackson api for parsing,it will be easy

 ObjectMapper mapper = new ObjectMapper();
 JsonNode node = mapper.readTree(json);
 if(node.get("results").isArray()){
 for(int i=0; i <= node.get("results").size()-1; i++){
 System.out.println(node.get("results").get(i));
 }

Answer 4

I used Gson api and was able to get the location. Try this :

Code::

 Gson gson = new Gson();
 String json = "your json";
 JsonObject map = gson.fromJson(json, JsonObject.class); // to be replaced with your restTemplate call
 JsonArray arr = map.getAsJsonArray("results");
 for (Object j : arr) {
 System.out.println(((JsonObject) j).get("geometry").getAsJsonObject().get("location"));
 }

Console Output::

{"lat":-36.8484597,"lng":174.7633315}
{"lat":-36.8484597,"lng":174.7633315}

So ideally just get the response as a JsonObject instead of a Map and you will be able to read the location.