Java : SequencedSet with Examples

SequencedSet (Java SE 21 & JDK 21) with Examples.
You will find code examples on most SequencedSet methods.

Summary

A collection that is both a SequencedCollection and a Set. As such, it can be thought of either as a Set that also has a well-defined encounter order, or as a SequencedCollection that also has unique elements.

Class diagram

final SequencedSet<String> set = new LinkedHashSet<>();

set.addLast("a");
set.addLast("b");
set.addLast("c");

System.out.println(set); // [a, b, c]
System.out.println(set.reversed()); // [c, b, a]

set.addFirst("X");
set.addFirst("Y");
set.addFirst("Z");

System.out.println(set); // [Z, Y, X, a, b, c]
System.out.println(set.reversed()); // [c, b, a, X, Y, Z]

Methods

SequencedSet<E> reversed ()

Returns a reverse-ordered view of this collection.

final SequencedSet<String> set = new LinkedHashSet<>();

set.addLast("aaa");
set.addLast("bbb");
set.addLast("ccc");

System.out.println(set); // [aaa, bbb, ccc]

final var reversedSet = set.reversed();
System.out.println(reversedSet); // [ccc, bbb, aaa]

System.out.println(reversedSet.reversed()); // [aaa, bbb, ccc]