Multi criteria sorting of a list of objects with Guava Ordering

Question

I have a class WHICH CANNOT implement comparable, but needs to be sorted based on 2 fields. How can I achieve this with Guava?

Let\'s say the class is:

c         


        

Answer 1

Java 8 provides methods on Comparator to concisely specify chained comparators. Together with the newly-introduced List.sort, you can do:

lotsOfX.sort(
    Comparator.comparingInt(x -> stringValueSortFunction.apply(x.stringValue))
        .thenComparing(x -> x.dateValue, Comparator.reverseOrder()));

This mutates the list, of course -- make a copy first if you want to leave the original list unchanged, or wrap the comparator in an Ordering and use immutableSortedCopy if you want an immutable copy.