Java tutorial
package com.patloew.countries.util; import com.google.gson.TypeAdapter; import com.google.gson.stream.JsonReader; import com.google.gson.stream.JsonToken; import com.google.gson.stream.JsonWriter; import com.patloew.countries.data.model.Country; import java.io.IOException; /* Copyright 2016 Patrick Lwenstein * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ public class CountryTypeAdapter extends TypeAdapter<Country> { public static final TypeAdapter<Country> INSTANCE = new CountryTypeAdapter().nullSafe(); private CountryTypeAdapter() { } @Override public void write(JsonWriter out, Country value) throws IOException { throw new UnsupportedOperationException(); } @Override public Country read(JsonReader in) throws IOException { try { Country country = new Country(); in.beginObject(); while (in.hasNext()) { String name = in.nextName(); switch (name) { case "alpha2Code": { // cannot be null, because it is the primary key country.alpha2Code = in.nextString(); break; } case "alpha3Code": { country.alpha3Code = JsonUtils.readNullSafeString(in); break; } case "name": { country.name = JsonUtils.readNullSafeString(in); break; } case "nativeName": { country.nativeName = JsonUtils.readNullSafeString(in); break; } case "region": { country.region = JsonUtils.readNullSafeString(in); break; } case "capital": { country.capital = JsonUtils.readNullSafeString(in); break; } case "population": { country.population = JsonUtils.readNullSafeInteger(in); break; } case "latlng": { if (in.peek() == JsonToken.NULL) { in.nextNull(); } else { in.beginArray(); if (in.hasNext()) { country.lat = JsonUtils.readNullSafeFloat(in); } if (in.hasNext()) { country.lng = JsonUtils.readNullSafeFloat(in); } in.endArray(); } break; } case "currencies": { country.currencies = RealmStringListTypeAdapter.INSTANCE.read(in); break; } case "borders": { country.borders = RealmStringListTypeAdapter.INSTANCE.read(in); break; } case "languages": { country.languages = RealmStringListTypeAdapter.INSTANCE.read(in); break; } case "translations": { country.translations = RealmStringMapEntryListTypeAdapter.INSTANCE.read(in); break; } default: in.skipValue(); break; } } in.endObject(); return country; } catch (Exception e) { throw new IOException(e); } } }