Google Maps coordinations JSON to object

Question

I am trying to write a parser from JSON data which I get from Google requesting coordinates of a city, which will create my specified object structure. For parsing, I've written a custom TypeAdapter.

It is my first time working with Gson, so probably my parsing method can be improved. Any suggestions?

JSON I receive:

 {
 "results" : [
 {
 "address_components" : [
 {
 "long_name" : "Los Angeles",
 "short_name" : "Los Angeles",
 "types" : [ "locality", "political" ]
 },
 {
 "long_name" : "Los Angeles County",
 "short_name" : "Los Angeles County",
 "types" : [ "administrative_area_level_2", "political" ]
 },
 {
 "long_name" : "California",
 "short_name" : "CA",
 "types" : [ "administrative_area_level_1", "political" ]
 },
 {
 "long_name" : "United States",
 "short_name" : "US",
 "types" : [ "country", "political" ]
 }
 ],
 "formatted_address" : "Los Angeles, CA, USA",
 "geometry" : {
 "bounds" : {
 "northeast" : {
 "lat" : 34.3373061,
 "lng" : -118.1552891
 },
 "southwest" : {
 "lat" : 33.7036917,
 "lng" : -118.6681759
 }
 },
 "location" : {
 "lat" : 34.0522342,
 "lng" : -118.2436849
 },
 "location_type" : "APPROXIMATE",
 "viewport" : {
 "northeast" : {
 "lat" : 34.3373061,
 "lng" : -118.1552891
 },
 "southwest" : {
 "lat" : 33.7036917,
 "lng" : -118.6681759
 }
 }
 },
 "partial_match" : true,
 "place_id" : "ChIJE9on3F3HwoAR9AhGJW_fL-I",
 "types" : [ "locality", "political" ]
 }
 ],
 "status" : "OK"
}

My POJO: only fields, without setters and getters to save space.

 public class GeoLocation {
 private String location_longName;
 private String location_shortName;
 private String country_longName;
 private String country_shortName;
 private String forrmatedAddress;
 private GeoCoordinates locationCordinates;
}
 public class GeoCoordinates {
 private Point northeastBounds;
 private Point southwestBounds;
 private Point northeastViewport;
 private Point southwestViewport;
 private Point location;
}

Custom TypeAdapter:

public class GeoLocationAdapter extends TypeAdapter<GeoLocation> {
 @Override
 public void write(JsonWriter jsonWriter, GeoLocation location) throws IOException {
 }
 @Override
 public GeoLocation read(JsonReader jsonReader) throws IOException {
 GeoLocation location = parsing(jsonReader);
 return location;
 }
 private GeoLocation parsing(JsonReader reader) throws IOException {
 GeoLocation location = new GeoLocation();
 GeoCoordinates coordinates = new GeoCoordinates();
 location.setLocationCordinates(coordinates);
 while (reader.peek() != JsonToken.END_DOCUMENT) {
 if (reader.peek() == JsonToken.NAME) {
 switch (reader.nextName()) {
 case "results":
 case "geometry":
 break;
 case "address_components":
 reader.beginArray();
 int i = 0;
 String longName = null;
 String shortName = null;
 for (; ; ) {
 if (reader.peek() == JsonToken.BEGIN_OBJECT) {
 reader.beginObject();
 }
 if (reader.peek() == JsonToken.NAME) {
 switch (reader.nextName()) {
 case "long_name":
 longName = reader.nextString();
 break;
 case "short_name":
 shortName = reader.nextString();
 break;
 case "types":
 while (reader.peek() != JsonToken.END_OBJECT) {
 reader.skipValue();
 }
 break;
 }
 }
 if (reader.peek() == JsonToken.END_OBJECT) {
 if (0 == i++) {
 location.setLocation_longName(longName);
 location.setLocation_shortName(shortName);
 }
 reader.endObject();
 }
 if (reader.peek() == JsonToken.END_ARRAY) {
 location.setCountry_longName(longName);
 location.setCountry_shortName(shortName);
 reader.endArray();
 break;
 }
 }
 break;
 case "formatted_address":
 location.setForrmatedAddress(reader.nextString());
 break;
 case "bounds":
 reader.beginObject();
 for (; ; ) {
 if (reader.peek() == JsonToken.NAME) {
 switch (reader.nextName()) {
 case "northeast":
 reader.beginObject();
 location.getLocationCordinates().setNortheastBounds(parseCoordinates(reader));
 reader.endObject();
 break;
 case "southwest":
 reader.beginObject();
 location.getLocationCordinates().setSouthwestBounds(parseCoordinates(reader));
 reader.endObject();
 break;
 }
 if (reader.peek() == JsonToken.END_OBJECT) {
 reader.endObject();
 break;
 }
 }
 }
 break;
 case "location":
 reader.beginObject();
 location.getLocationCordinates().setLocation(parseCoordinates(reader));
 reader.endObject();
 break;
 case "viewport":
 reader.beginObject();
 for (; ; ) {
 if (reader.peek() == JsonToken.NAME) {
 switch (reader.nextName()) {
 case "northeast":
 reader.beginObject();
 location.getLocationCordinates().setNortheastViewport(parseCoordinates(reader));
 reader.endObject();
 break;
 case "southwest":
 reader.beginObject();
 location.getLocationCordinates().setSouthwestViewport(parseCoordinates(reader));
 reader.endObject();
 break;
 }
 if (reader.peek() == JsonToken.END_OBJECT) {
 reader.endObject();
 break;
 }
 }
 }
 break;
 default:
 reader.skipValue();
 break;
 }
 }
 if (reader.peek() == JsonToken.BEGIN_OBJECT) {
 reader.beginObject();
 }
 if (reader.peek() == JsonToken.BEGIN_ARRAY) {
 reader.beginArray();
 }
 if (reader.peek() == JsonToken.END_OBJECT) {
 reader.endObject();
 }
 if (reader.peek() == JsonToken.END_ARRAY) {
 reader.endArray();
 }
 }
 return location;
 }
 private Point parseCoordinates(JsonReader reader) throws IOException {
 Double lat = null;
 Double lng = null;
 while (reader.peek() != JsonToken.END_OBJECT) {
 switch (reader.nextName()) {
 case "lat":
 lat = reader.nextDouble();
 break;
 case "lng":
 lng = reader.nextDouble();
 break;
 }
 }
 return new Point(lat, lng);
 }
}

Calling:

 GsonBuilder builder = new GsonBuilder();
 builder.registerTypeAdapter(GeoLocation.class, new GeoLocationAdapter());
 Gson gson = builder.create();
 GeoLocation locationObj = gson.fromJson(full, GeoLocation.class);

Please provide any improvements that can be made to code for ac-heaving better readability and performance. Also, can I leave the write method empty if I'm not planning to convert the result object back to JSON?

• Tunaki: Any reason not to use a JsonParser? The code would be much shorter.
• Edgar: was not aware of it, should try probably. Maybe you can explain a little how to implement it in my case?

Answer 1

You can parse the complete response easily using Google's Gson library:

class GeoResponse {
 List<Result> results;
 String status;
 static class Result {
 List<AddressComponent> address_components;
 String formatted_address;
 Geometry geometry;
 boolean partial_match;
 String place_id;
 List<String> types;
 static class AddressComponent {
 String long_name, short_name;
 List<String> types;
 }
 static class Geometry {
 Rect bounds;
 LatLng location;
 String location_type;
 Rect viewport;
 static class Rect {
 LatLng northeast, southwest;
 }
 static class LatLng {
 double lat, lng;
 }
 }
 }
}
...
import com.google.gson.Gson;
class GeoResponseParser {
 Gson gson = new Gson();
 GeoResponse parse(String responseStr) {
 return gson.fromJson(responseStr, GeoResponse.class);
 }
}

• Edgar: yea it works, but I wanted to make different structure of object.
• Reinstate Monica: @Edgar Then I would recommend letting Gson do the conversion to a Java object and then convert that object to one of the structure you want.