Deserializing into class extending LinkedHashMap with Gson

Question

I'm trying to deserialize from JSON into a class that extends LinkedHashMap with Gson. I'm able to do this trivially directly into a LinkedHashMap, but when I try to use the sub-class of LinkedHashMap, I get the error

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 3 path $.

The type I need to use (I don't own this, so there's no option to use anything else):

public class ValueMap extends LinkedHashMap<CharSequence, Object> {}

I've had to define an InstanceCreator to work around issues with CharSequence. The JSON I'm trying to deserialize as a basic example is:

{"people":[{"name":"name1","surname":"name2","age":12,"dogs":["spot","fluffy","batman"],"cars":[{"name":"name1","model":1933},{"name":"name2","model":343}]},{"name":"name2","surname":"name2","age":44,"dogs":["spot","test","jack"]}]}

Updated to include serialization/deserialization code:

GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(CharSequence.class, new CharSequenceInstanceCreator());

Gson gson = gsonBuilder.create();

String serialized = gson.toJson(value);

LinkedHashMap<CharSequence, Object> deserialized = gson.fromJson(serialized, ValueMap.class);

Where CharSequenceInstanceCreator looks like:

public static class CharSequenceInstanceCreator implements InstanceCreator<CharSequence> {

    @Override
    public CharSequence createInstance(Type arg0) {
        return new String();
    }

}

Answer 1

Define JsonDeserializer instead of InstanceCreator.

public static class CharSequenceDeserializer implements JsonDeserializer<CharSequence> {

    @Override
    public CharSequence deserialize(JsonElement element, Type type,
            JsonDeserializationContext context) throws JsonParseException {
        return element.getAsString();
    }

}

and register it.

//  gsonBuilder.registerTypeAdapter(CharSequence.class, new CharSequenceInstanceCreator());
gsonBuilder.registerTypeAdapter(CharSequence.class, new CharSequenceDeserializer());