Parse dates on Api response level

DateDeserializer.java

public class DateDeserializer implements JsonDeserializer<MyDate> {
    //if not epoch time from server response
    public static SimpleDateFormat serverFormatter = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss.SSS'Z'");
    public static SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");

    @Override
    public MyDate deserialize(JsonElement element, Type arg1, JsonDeserializationContext arg2) throws JsonParseException {
        String date = element.getAsString();
        //if epoch sent then create date object directly new Date(time*1000)
        formatter.setTimeZone(TimeZone.getTimeZone("UTC"));//the timezones you want
        serverFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
        try {
            //skip this step if you get epochtime from server
            Date serverDate = serverFormatter.parse(date);
            return new MyDate(formatter.format(serverDate), serverDate);
        } catch (ParseException e) {
            System.err.println("Failed to parse Date due to:" + e);
            return null;
        }
    }
}

Gson.java

 private static GsonConverterFactory getGsonFactory() {
        //Here you can create your own deserializers 
        //so what it will do is when it finds the dob from json response which is ideally string or long and calls this serializer to provide mydate instance
        //and then deserialize method called with the json response value which can be 140005666... something like that epoch or date 
        // and deserializer will response the object from which you can get date formatted value
        Gson gson = new GsonBuilder().setLenient().registerTypeAdapter(MyDate.class, new DateDeserializer()).create();
        return GsonConverterFactory.create(gson);
 }

MyDate.java

public class MyDate implements Serializable {
    private int mId;
    private String formattedDate;
    //still if you do want original date
    private Date date;
    ....
    public MyDate(String value, Date date) {
        this.val = value;
        this.date = date;
    }
}

ReponseModel.java

public class ReponseModel implements Serializable {
    @SerializedName("dob")
    private MyDate dob;
    ....
}

RetrofitLevel.java

 Retrofit retrofit = new Retrofit.Builder().baseUrl(apiUrlProvider())//LOCAL_BASE_URL
                    .addConverterFactory(getGsonFactory()).addCallAdapterFactory(RxJavaCallAdapterFactory.create()).client(client).build();