java 8, Sort list of objects by attribute without custom comparator
Assuming you actually have a List<AnObject>
, all you need is
list.sort(Comparator.comparing(a -> a.attr));
If you make you code clean by not using public fields, but accessor methods, it becomes even cleaner:
list.sort(Comparator.comparing(AnObject::getAttr));
As a complement to @JB Nizet's answer, if your attr is nullable,
list.sort(Comparator.comparing(AnObject::getAttr));
may throw a NPE.
If you also want to sort null values, you can consider
list.sort(Comparator.comparing(a -> a.attr, Comparator.nullsFirst(Comparator.naturalOrder())));
or
list.sort(Comparator.comparing(a -> a.attr, Comparator.nullsLast(Comparator.naturalOrder())));
which will put nulls first or last.