Gson deserialization of List into realmList

It is better to use JsonSerializer and JsonDeserializer rather than TypeAdapter for your RealmObject, because of 2 reasons:

1. They allow you to delegate (de)serialization for your RealmObject to the default Gson (de)serializer, which means you don’t need to write the boilerplate yourself.

2. There’s a weird bug in Gson 2.3.1 that might cause a StackOverflowError during deserialization (I tried the TypeAdapter approach myself and encountered this bug).

Here’s how (replace Tag with your RealmObject class):

(NOTE that context.serialize and context.deserialize below are equivalent to gson.toJson and gson.fromJson, which means we don’t need to parse the Tag class ourselves.)

Parser + serializer for RealmList<Tag>:

public class TagRealmListConverter implements JsonSerializer<RealmList<Tag>>,
        JsonDeserializer<RealmList<Tag>> {

    @Override
    public JsonElement serialize(RealmList<Tag> src, Type typeOfSrc,
                                 JsonSerializationContext context) {
        JsonArray ja = new JsonArray();
        for (Tag tag : src) {
            ja.add(context.serialize(tag));
        }
        return ja;
    }

    @Override
    public RealmList<Tag> deserialize(JsonElement json, Type typeOfT,
                                      JsonDeserializationContext context)
            throws JsonParseException {
        RealmList<Tag> tags = new RealmList<>();
        JsonArray ja = json.getAsJsonArray();
        for (JsonElement je : ja) {
            tags.add((Tag) context.deserialize(je, Tag.class));
        }
        return tags;
    }

}

Tag class:

@RealmClass
public class Tag extends RealmObject {
    private String value;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }
}

Then register your converter class with Gson:

Gson gson = new GsonBuilder()
        .registerTypeAdapter(new TypeToken<RealmList<Tag>>() {}.getType(),
                new TagRealmListConverter())
        .create();