How can I get the values of an "enum" in a generic?

Class::getEnumConstants

You cannot directly get it from T because generics are erased by the Java compiler so at runtime it is no longer known what T is.

What you can do is require a Class<T> object as constructor parameter. From there you can get an array of the enum objects by calling Class::getEnumConstants.

public class Sorter<T extends Enum<T>> {
    public Sorter(Class<T> clazz) {
        final T[] enumConstants = clazz.getEnumConstants();
    }
}