how to get Class<X<T>> by guava TypeToken

Question

There're two class, one named Service, the other named Domain.

class Domain<T> {
    String id;
    // some other common fields and methods
    T data;
    T getData() {
        return data;
    }

class Service<T> {
    T get(String id) {
        // here's we need a Class<Domain<T>> to do some work
        TypeToken<Domain<T>> typeToken = new TypeToken<Domain<T>>(getClass()){};
        // how to get `Class<Domain<T>>` from `typeToken` 
        Class<Domain<T>> = ...
    }
}

So, how to get Class<Domain<T>> from TypeToken<Domain<T>> ?

Answer 1

For the record, asking "How do I retrieve a generic type from MongoTemplate.findOne() ?" would likely get you a much better answer .

The MongoTemplate API doesn't accept TypeToken or any other generic-capturing mechanism. That means it doesn't safely support returning generic types. Assuming you know at compile-time what the type should be you can do an unsafe cast, however:

Domain<T> domain = (Domain<T>) template.findOne(query, Domain.class);

Notice that this passes in Domain.class , so findOne() will return a raw Domain instance, which then needs to be cast to Domain<T> to avoid working with a raw type.