Java generics warnings on java.util.Collections

Question

I have a method:

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

    return toSort;
}

This produces a warning:

Type safety: Unchecked invocation sort(List<Stuff>) of the generic method sort(List<T>) of type Collections.

Eclipse says the only way to fix the warning is to add @SuppressWarnings("unchecked") to my sortStuff method. That seems like a crummy way to do with something that is built into Java itself.

Is this really my only option here? Why or why not? Thanks in advance!

Answer 1

Collections.sort(List<T>) expects that T must implement Comparable<? super T>. It seems like Stuff does implement Comparable but doesn't provide the generic type argument.

Make sure to declare this:

public class Stuff implements Comparable<Stuff>

Instead of this:

public class Stuff implements Comparable