java - Gson TypeToken with dynamic ArrayList item type

Question

I have this code:

Type typeOfObjectsList = new TypeToken<ArrayList<myClass>>() {}.getType();
List<myClass> objectsList = new Gson().fromJson(json, typeOfObjectsList);

It converts a JSON string to a List of objects. But now I want to have this ArrayList with a dynamic type (not just myClass), defined at runtime.

The ArrayList's item type will be defined with reflection.

I tried this:

    private <T> Type setModelAndGetCorrespondingList2(Class<T> type) {
        Type typeOfObjectsListNew = new TypeToken<ArrayList<T>>() {}.getType();
        return typeOfObjectsListNew;
    }

But it doesn't work. This is the exception:

java.sql.SQLException: Fail to convert to internal representation: {....my json....}

Answer 1

Since Gson 2.8.0, you can use TypeToken#getParameterized(Type rawType, Type... typeArguments) to create the TypeToken, then getType() should do the trick.

For example:

TypeToken.getParameterized(ArrayList.class, myClass).getType()