CODEWITHSUNDEEP
javagenericsoverloading
alam-hasabie
alam-hasabie

Reputation: 11

How to overload generic function with more specific type parameter?

Suppose I have a generic class

public class A<T> {}

Then , A is instantiated with B and C, with C extends from another class D :

public class B {}
public class C extends D {}

A<B> b = new A<>();
A<C> c = new A<>();

What I'm trying to do is creating a method which accepts A<T> a as a parameter. However, I plan to overload the function, so that the instance whose type parameter extends from D can be handled differently.

public class X {
    public static void fun(A<?> a) {}
    public static void fun(A<? extends D> a) {}
}

However, the code above cannot be compiled, since it seems that the second func also bounds to Object. My question would be how to handle such case ? Should I just use instanceof , or is there any neater way to accomplish this ?

Edit : I'm trying to create a function which can handle specific classes with overloading, but there's a catch-all function that will handle other non-specified classes, since I cannot know in advance what classes are going to be used for the type parameter

Upvotes: 1

Views: 303

Answers (1)

Andreas
Andreas

Reputation: 159086

it seems that the second func also bounds to Object

That is incorrect.

Because of type erasure, the generics are removed, so they both become:

public static void fun(A a) {}
public static void fun(A a) {}

Solution: Don't use overloading, use different method names.

Upvotes: 2

Related Questions