JEP 431: Sequenced Collections

Author: ibrahimatay

README.md

@@ -7,6 +7,7 @@ This repository contains Java examples that are designed to track and document t
 
 * [Java 21](java-21) (September, 2023)
   * [JEP 430](https://openjdk.org/jeps/430): String Templates
+  * [JEP 431](https://openjdk.org/jeps/431): Sequenced Collections
 
 * [Java 16](java-16/) (March, 2021)
   * [JEP 395](https://openjdk.java.net/jeps/395): Records

java-21/src/main/java/com/ibrahimatay/JEP431SequencedCollections.java

@@ -0,0 +1,96 @@
+package com.ibrahimatay;
+
+import java.util.*;
+
+/*
+* JEP 431: Sequenced Collections
+* https://openjdk.org/jeps/431
+* */
+public class JEP431SequencedCollections {
+    public static void main(String[] args) {
+        /*
+        interface SequencedSet<E> extends SequencedCollection<E>, Set<E> {
+            SequencedSet<E> reversed();
+        }
+        * */
+
+        LinkedHashSet<Integer> linkedHashSet = new LinkedHashSet<>(List.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9));
+
+        System.out.println(STR."Fist item: \{linkedHashSet.getFirst()} in LinkedHashSet"); // Fist item: 1=One
+        System.out.println(STR."Last item: \{linkedHashSet.getLast()}  in LinkedHashSet"); // Last item: 3=Three
+
+        linkedHashSet.addFirst(0);
+        linkedHashSet.addLast(4);
+
+        System.out.println(linkedHashSet.reversed());
+
+        /*
+         interface SequencedMap<K,V> extends Map<K,V> {
+          // New Methods
+          SequencedMap<K,V> reversed();
+
+          SequencedSet<K> sequencedKeySet();
+          SequencedCollection<V> sequencedValues();
+          SequencedSet<Entry<K,V>> sequencedEntrySet();
+
+          V putFirst(K, V);
+          V putLast(K, V);
+
+
+          // Promoted Methods from NavigableMap<K, V>
+
+          Entry<K, V> firstEntry();
+          Entry<K, V> lastEntry();
+
+          Entry<K, V> pollFirstEntry();
+          Entry<K, V> pollLastEntry();
+        }
+        * */
+
+        LinkedHashMap<Integer, String> map = new LinkedHashMap<>();
+
+        map.put(1, "One");
+        map.put(2, "Two");
+        map.put(3, "Three");
+
+        System.out.println(STR."Fist item: \{map.firstEntry()}"); // Fist item: 1=One
+        System.out.println(STR."Last item: \{map.lastEntry()}"); // Last item: 3=Three
+
+        System.out.println(map); // {1=One, 2=Two, 3=Three}
+
+        Map.Entry<Integer, String> firstMap = map.pollFirstEntry();
+        System.out.println(firstMap); // 1=One
+        Map.Entry<Integer, String> lastMap = map.pollLastEntry();
+        System.out.println(lastMap); // 3=Three
+
+        System.out.println(map.reversed());
+
+        /*
+        interface SequencedCollection<E> extends Collection<E> {
+          // New Method
+
+          SequencedCollection<E> reversed();
+
+          // Promoted methods from Deque<E>
+
+          void addFirst(E);
+          void addLast(E);
+
+          E getFirst();
+          E getLast();
+
+          E removeFirst();
+          E removeLast();
+        }
+        * */
+
+        ArrayList<Integer> arrayList = new ArrayList<>();
+
+        arrayList.add(1);
+        arrayList.addFirst(0);
+        arrayList.addLast(2);
+
+        System.out.println(STR."Fist item: \{arrayList.getFirst()} in ArrayList"); // Fist item: 0 in ArrayList
+        System.out.println(STR."Last item: \{arrayList.getLast()} in ArrayList"); // Last item: 2 in ArrayList
+    }
+}