fin arbre

DEV3.2/Files/chaine/LinkedQueue.java

@@ -0,0 +1,79 @@
+import java.util.AbstractQueue;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+public class LinkedQueue<E> extends AbstractQueue<E> {
+
+    private Node<E> head; // Tête de la file
+    private Node<E> tail; // Fin de la file
+    private int size;     // Taille de la file
+
+    public LinkedQueue() {
+        head = null;
+        tail = null;
+        size = 0;
+    }
+
+    @Override
+    public boolean offer(E e) {
+        if (e == null) {
+            throw new NullPointerException("Les éléments null ne sont pas autorisés.");
+        }
+        Node<E> newNode = new Node<>(e);
+        if (tail == null) { // File vide
+            head = newNode;
+            tail = newNode;
+        } else {
+            tail.next = newNode;
+            tail = newNode;
+        }
+        size++;
+        return true;
+    }
+
+    @Override
+    public E poll() {
+        if (head == null) { // File vide
+            return null;
+        }
+        E element = head.element;
+        head = head.next;
+        if (head == null) { // La file est maintenant vide
+            tail = null;
+        }
+        size--;
+        return element;
+    }
+
+    @Override
+    public E peek() {
+        return (head == null) ? null : head.element;
+    }
+
+    @Override
+    public Iterator<E> iterator() {
+        return new Iterator<E>() {
+            private Node<E> current = head;
+
+            @Override
+            public boolean hasNext() {
+                return current != null;
+            }
+
+            @Override
+            public E next() {
+                if (current == null) {
+                    throw new NoSuchElementException();
+                }
+                E element = current.element;
+                current = current.next;
+                return element;
+            }
+        };
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+}