Hey Henri,
On Fri, Aug 26, 2011 at 11:50 PM, Henri Yandell <[email protected]> wrote:
> Thanks James.
>
> I wanted to pull the comparator classes over from Collections as I
> wanted to still be able to support them (and use internally as I
> already had ComparableComparator hidden away) without having to deal
> with all of Collections.
>
> Maybe the answer though is to ignore them in favour of Ordering, much
> the way we've long ignored the Date API in favour of Joda Time.
>
> It looks like:
>
> ComparableComparator = Ordering.natural
> ReverseComparator = Ordering.reverse
> NullComparator = Ordering.nullsFirst/nullsLast
> ComparatorChain = Ordering.from + Ordering.compound
> FixedOrderComparator = Ordering.explicit
I think one of the most useful methods is onResultOf, e.g.
class Person {
public static final Function<Person, String> lastNameFunction = new
Function<Person, String>() {
@Override public String apply(Person input) {
return person.getLastName();
}
}
...
}
List<Person> people = ...;
Ordering<Person> lastNameOrdering =
Ordering.natural().reverse().onResultOf(lastNameFunction);
List<Person> sortedPeople = lastNameOrdering.immutableSortedCopy(people);
> Hen
Regards,
James
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