Java generics - ensure static method is implemented

Question

I'm using generics like this: public class MyList<T> . Is there any way to ensure that the class represented by T implements a certain static method?

Answer 1

No, even without generics there is never a way to ensure a class implements a static method.

You can, however, create a generic static method.

public static <T> List<T> makeSingletonList(T item) {
      ArrayList<T> result = new ArrayList<T>();
      result.add(item);
      return result;
}

Answer 2

Unfortunately not.

As an alternative, consider whether the static methods of your class belongs in some sort of associated class like a builder:

class Person {
    public static Person createFromDatastore(Datastore datastore) { ... }
}

It may be better to move the static to a separate class as a non-static method:

class PersonBuilder implements Builder<Person> {
     public Person createFromDatastore(Datastore datastore) { ... }
}

This means that you can dictate clients of your generic class can now be required to provide it:

public class MyList<B extends Builder<T>, T> ...