comparators.clj

user> (import '(java.util ArrayList Collections Comparator))
java.util.Comparator
user> (def array-list (doto (ArrayList.)
                        (.add 1)
                        (.add 5)
                        (.add 2)))
#'user/array-list
user> array-list
[1 5 2]
user> (Collections/sort array-list
                        (reify Comparator
                          (compare [_ x y] (- y x))))
nil
user> array-list
[5 2 1]
user> (def array-list (doto (ArrayList.)
                        (.add 1)
                        (.add 5)
                        (.add 2)))
#'user/array-list
user> (Collections/sort array-list
                        #(compare %2 %1))
nil
user> array-list
[5 2 1]
user> (def array-list (doto (ArrayList.)
                        (.add 1)
                        (.add 5)
                        (.add 2)))
#'user/array-list
user> (Collections/sort array-list
                        #(- %2 %1))
nil
user> array-list
[5 2 1]