Do you believe that Set.equals() should behave this way on SortedSets?
> On May 20, 2020, at 11:23 AM, Jason Mehrens <jason_mehr...@hotmail.com> wrote:
>
> public class SetEquals {
>
> public static void main(String[] args) {
> Comparator<String> cc = String.CASE_INSENSITIVE_ORDER;
> Set<String> s1 = new TreeSet<>(cc);
> Set<String> s2 = new TreeSet<>(cc);
> s1.add("hello");
> s2.add("Hello");
> System.out.println(equals(s1, s2));
> System.out.println(equals(s2, s1));
> System.out.println(s1.hashCode() == s2.hashCode());
> }
>
> private static boolean equals(Set<?> s1, Set<?> s2) {
> if (s2 == null) {
> return false;
> }
>
> if (s1 == s2) {
> return true;
> }
>
> int s1h = 0;
> int s2h = 0;
> Iterator<?> e1 = s1.iterator();
> Iterator<?> e2 = s2.iterator();
>
> if (s1 instanceof SortedSet && s2 instanceof SortedSet
> && isSameOrder((SortedSet) s1, (SortedSet) s2)) {
> //TODO: raw type warnings.
> Comparator cmp = ((SortedSet<?>) s1).comparator();
> if (cmp == null) {
> cmp = Comparator.naturalOrder();
> }
> while (e1.hasNext() && e2.hasNext()) {
> Object o1 = e1.next();
> Object o2 = e2.next();
>
> try {
> if (cmp.compare(o1, o2) != 0
> && (!s1.contains(o2) || !s2.contains(o1))) {
> return false;
> }
> } catch (ClassCastException cce) {
> return false;
> }
>
> s1h += Objects.hashCode(o1);
> s2h += Objects.hashCode(o2);
>
> //Iteration order should be the same.
> if (s1h != s2h) {
> return false;
> }
> }
> } else {
> while (e1.hasNext() && e2.hasNext()) {
> Object o1 = e1.next();
> Object o2 = e2.next();
>
> try {
> if (!Objects.equals(o1, o2)
> && (!s1.contains(o2) || !s2.contains(o1))) {
> return false;
> }
> } catch (ClassCastException cce) {
> return false;
> }
>
> s1h += Objects.hashCode(o1);
> s2h += Objects.hashCode(o2);
> }
> }
> return s1h == s2h && !e1.hasNext() && !e2.hasNext();
> }
>
> private static boolean isSameOrder(SortedSet<?> s1, SortedSet<?> s2) {
> //null matches natural ordering or unwrap to find a singleton.
> //Avoid calling equals on comparator.
> return Collections.reverseOrder(s1.comparator())
> == Collections.reverseOrder(s2.comparator());
> }
> }
