Question

I have a class

public abstract class FakeClass<T extends MyClass> {
    protected HashMap<Character, T> myMap;

    private void myMethod(){
        myMap.put('c', /*???? I need to instatiate something of type T here.*/)
    }
}

As you can see, I can’t figure out how to instantiate something of type T. Is this possible? If so can someone point me in the right direction to do it?

Thanks!

Answer 1

This can only be done by passing some information about T to myMethod(). One approach, described in this thread, is to pass a factory object for T. A special case of this, described in this thread, is to pass a Class<T> type argument to myMethod(), which can then use type.newInstance() to create a new T object using the default constructor. (This will fail if T does not have a default constructor.) The Class object serves as the factory object for T.

The reason we need all this is due to type erasure in Java.