Generic static method constrains types too much

Question

In this answer I attempted to create a static utility method to make a List into a Map:

public static  Map toMa         


        

Answer 1

You could add a type parameter for the values of the map so they can be different from T:

public static  Map toMapBy(List list,
        Function mapper) {
    return list.stream().collect(Collectors.toMap(mapper, Function.identity()));
}