Does a natural comparator exist in the standard api?

java comparator comparable
Yishai picture Yishai · Jul 13, 2010 · Viewed 31.9k times · Source

I need a comparator as part of a strategy pattern that can either use the natural ordering of the objects or some custom ordering. For the natural ordering case, I wrote a simple comparator:

private static class NaturalComparator<T extends Comparable<? super T>> implements Comparator<T> {
    @Override
    public int compare(T o1, T o2) {
        return o1.compareTo(o2);
    }
}

Seems simple enough, but I was wondering if anyone knew of one in the standard API. I looked at TreeMap, and it does it without such a class, so when that code was written, the apparent answer would be no, but perhaps it was added later.

Answer

Julien picture Julien · Nov 4, 2013

Added to Comparator in Java 8:

static <T extends Comparable<? super T>> Comparator<T> naturalOrder()

Use it like this, for example:

Comparator<Double> natural = Comparator.<Double>naturalOrder();
return natural.compare(1.0, 1.1));

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