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Answer for this question about Gson: http://stackoverflow.com/questions/20442265/how-to-decode-json-with-unknown-field-using-gson. This demonstrates how to use custom deserialiser to parse a big list of properties of the same type but unknown/random/varying names. Besides JDK, depends on Guava library.
import com.google.common.base.Charsets;
import com.google.common.io.Files;
import com.google.gson.*;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
/**
* http://stackoverflow.com/questions/20442265/how-to-decode-json-with-unknown-field-using-gson
*
* @author: jonik, http://stackoverflow.com/users/56285/jonik
* Date: 7.12.2013
*/
public class Question20442265 {
public static void main(String[] args) throws IOException {
// using this test JSON: https://www.dropbox.com/s/a89s0ysv2cr8w44/question20442264.json?dl=0
File jsonFile = new File("src/gson/", "question20442264.json");
String json = Files.toString(jsonFile, Charsets.UTF_8);
GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(CityList.class, new CityListDeserializer());
Gson gson = builder.setFieldNamingPolicy(LOWER_CASE_WITH_UNDERSCORES).create();
CityList list = gson.fromJson(json, CityList.class);
System.out.println(list.cities);
}
private static class CityList {
List<City> cities;
private CityList(List<City> cities) {
this.cities = cities;
}
}
private static class City {
String citiesId;
String city;
String regionName;
// and so on
@Override
public String toString() {
return "City{" +
"citiesId='" + citiesId + '\'' +
", city='" + city + '\'' +
", regionName='" + regionName + '\'' +
'}';
}
}
private static class CityListDeserializer implements JsonDeserializer<CityList> {
@Override
public CityList deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext context) throws JsonParseException {
JsonObject object = jsonElement.getAsJsonObject();
List<City> cities = new ArrayList<City>();
for (Map.Entry<String, JsonElement> entry : object.entrySet()) {
// System.out.println(entry.getKey() + " " + entry.getValue());
// Use default deserialisation for City objects:
City city = context.deserialize(entry.getValue(), City.class);
cities.add(city);
}
return new CityList(cities);
}
}
}
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