Reverse a comparator in Java 8

You can use Comparator.reverseOrder() to have a comparator giving the reverse of the natural ordering.

If you want to reverse the ordering of an existing comparator, you can use Comparator.reversed().

Sample code:

Stream.of(1, 4, 2, 5)
    .sorted(Comparator.reverseOrder()); 
    // stream is now [5, 4, 2, 1]

Stream.of("foo", "test", "a")
    .sorted(Comparator.comparingInt(String::length).reversed()); 
    // stream is now [test, foo, a], sorted by descending length

You can also use Comparator.comparing(Function, Comparator)
It is convenient to chain comparators when necessary, e.g.:

Comparator<SomeEntity> ENTITY_COMPARATOR = 
        Comparator.comparing(SomeEntity::getProperty1, Comparator.reverseOrder())
        .thenComparingInt(SomeEntity::getProperty2)
        .thenComparing(SomeEntity::getProperty3, Comparator.reverseOrder());

Java 8 Comparator interface has a reversed method : https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html#reversed--