Methods with two Generics in Java

Question

I have a problem and want to ask you guys why this code doesn't work and how can I make it work without deleting generics or Methods. I think it's because the method cannot be overloaded since S and T can be the same type, is it correct? But I still have no idea know how to make it work. Thank you!

public class GenericFail<S,T> {
    public void doAnything(S sValue){
        System.out.println("Doing anything with S");
    }

    public void doAnything(T sValue){
        System.out.println("Doing anything with T");
    }
}

Answer 1

The generic type is erased after compilation. So the two doAnything() method have the same signature :

doAnything(Object object)

since S and T don't explicitly derive from a more specific type.

To solve the problem : either change the method name to have two distinct names or make S and T derive from a specific type such as :

public class GenericFail<S extends CharSequence, T extends Number> {

Answer 2

Because of type erasure the two methods have the same signature, thats not allowed in java. You need to use a workaround.

Your options:

• Change the erasure of the generic types by adding type bounds

  class GenericFail<S extends Number, T extends Collection<?>>

• Change the names of the methods, eg have doSAnything and doTAnything