How to serialize Date to long using gson?

Question

I recently switched some of our serialization from Jackson to Gson. Found out that Jackson serializes dates to longs.

But, Gson serializes Date

Answer 1

You can do both direction with one type adapter:

public class DateLongFormatTypeAdapter extends TypeAdapter {

    @Override
    public void write(JsonWriter out, Date value) throws IOException {
        if(value != null) out.value(value.getTime());
        else out.nullValue();
    }

    @Override
    public Date read(JsonReader in) throws IOException {
        return new Date(in.nextLong());
    }

}

Gson builder:

Gson gson = new GsonBuilder()
        .registerTypeAdapter(Date.class, new DateLongFormatTypeAdapter())
        .create();