Java generics warnings on java.util.Collections

Question

I have a method:

public List sortStuff(List toSort) {
    java.util.Collections.sort(toSort);

    return toSort;
}

T

Answer 1

Sorting Generic Collections

There are two sorting functions defined in this class, shown below:

public static > void sort(List list);

public static  void sort(List list, Comparator c);

Neither one of these is exactly easy on the eyes and both include the wildcard (?) operator in their definitions. The first version accepts a List only if T extends Comparable directly or a generic instantiation of Comparable which takes T or a superclass as a generic parameter. The second version takes a List and a Comparator instantiated with T or a supertype.