Serializing custom object that contains JodaTime objects into JSON

Question

After running a second activity that creates an object and stores it into an ArrayList inside of a Singleton I get this error when returning to the

Answer 1

Converters from https://github.com/gkopff/gson-javatime-serialisers are for java.time classes from Java8, e.g. java.time.LocalDate.

But you need converters for org.joda.time classes from 3rd part library. You can create custom converters for it, like:

Converter for org.joda.time.LocalDate

public class LocalDateSerializer implements JsonDeserializer<LocalDate>, JsonSerializer<LocalDate>
{
   private static final DateTimeFormatter DATE_FORMAT = ISODateTimeFormat.date();

   @Override
   public LocalDate deserialize(final JsonElement je, final Type type,
                           final JsonDeserializationContext jdc) throws JsonParseException
   {
      final String dateAsString = je.getAsString();
      if (dateAsString.length() == 0)
      {
         return null;
      }
      else
      {
         return DATE_FORMAT.parseLocalDate(dateAsString);         
      }
   }

   @Override
   public JsonElement serialize(final LocalDate src, final Type typeOfSrc,
                                final JsonSerializationContext context)
   {
      String retVal;
      if (src == null)
      {
         retVal = "";
      }
      else
      {
         retVal = DATE_FORMAT.print(src);
      }
      return new JsonPrimitive(retVal);
   }
}   

Converter for org.joda.time.LocalTime

public class LocalTimeSerializer implements JsonDeserializer<LocalTime>, JsonSerializer<LocalTime>
{

   private static final DateTimeFormatter TIME_FORMAT = ISODateTimeFormat.timeNoMillis();

   @Override
   public LocalTime deserialize(final JsonElement je, final Type type,
                           final JsonDeserializationContext jdc) throws JsonParseException
   {
      final String dateAsString = je.getAsString();
      if (dateAsString.length() == 0)
      {
         return null;
      }
      else
      {
         return TIME_FORMAT.parseLocalTime(dateAsString);         
      }
   }

   @Override
   public JsonElement serialize(final LocalTime src, final Type typeOfSrc,
                                final JsonSerializationContext context)
   {
      String retVal;
      if (src == null)
      {
         retVal = "";
      }
      else
      {
         retVal = TIME_FORMAT.print(src);
      }
      return new JsonPrimitive(retVal);
   }

}  

Usage

public void retrieveGlobalDataFromStorage(Context context)
{  
// ...  

    final GsonBuilder builder = new GsonBuilder()
       .registerTypeAdapter(LocalDate.class, new LocalDateSerializer())
       .registerTypeAdapter(LocalTime.class, new LocalTimeSerializer());
    final Gson gson = builder.create();  
// ...