Nice general way to sort nulls to the bottom, regardless?

Question

I\'m writing some custom Comparators, and I\'d like them to push null items to the bottom of the list, regardless of whether I\'m sorting ascending or descending. What\'s a

Answer 1

In Java 8, you can use the Comparator.nullsLast and Comparator.nullsFirst static methods to have more null-friendly comparators. Suppose you have a Fruit class like the following:

public class Fruit {
    private final String name;
    private final Integer size;

    // Constructor and Getters
}

If you want to sort a bunch of fruits by their size and put the nulls at the end:

List fruits = asList(null, new Fruit("Orange", 25), new Fruit("Kiwi", 5));

You can simply write:

Collections.sort(fruits, Comparator.nullsLast(Comparator.comparingInt(Fruit::getSize)));

And the result would be:

[Fruit{name='Kiwi', size=5}, Fruit{name='Orange', size=25}, null]