Why is List not a sub-type of List<Object>?

Answer 1

They aren't subtypes of each other due how generics work. What you want is to declare your function like this:

public void wahey(List list) {}

Then it will accept a List of anything that extends Object. You can also do:

public void wahey(List list) {}

This will let you take in Lists of something that's a subclass of Number.

I'd recommend you pick up a copy of "Java Generics and Collections" by Maurice Naftalin & Philip Wadler.