feat: add QueueInterfaceDemo illustrating Java Queue operations and behavior

Implemented QueueInterfaceDemo.java demonstrating FIFO operations using
LinkedList and ArrayBlockingQueue. Covers key Queue methods (add, offer,
remove, poll, peek) and contrasts bounded vs unbounded queue behavior.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section 25 Collections Frameworks/Queue Interface/src/QueueInterfaceDemo.java

@@ -2,25 +2,16 @@
 import java.util.Queue;
 import java.util.concurrent.ArrayBlockingQueue;
 
-/* QueueInterface
- * This class demonstrates how the Queue interface works in Java
- * using two implementations:
- *   1. LinkedList (unbounded queue).
- *   2. ArrayBlockingQueue (bounded queue with fixed capacity).
-
- * Queue follows FIFO (First In, First Out).
- * Key methods: add(), offer(), remove(), poll(), element(), peek().
- */
-
 public class QueueInterfaceDemo {
     public static void main(String[] args) {
-        // ---------------- Queue with LinkedList ----------------
+        // Queue with LinkedList
         Queue<Integer> queue1 = new LinkedList<>();
 
         // Add elements (FIFO order).
         queue1.add(1);
         queue1.add(3);
         queue1.add(2);
+        queue1.add(4);
 
         System.out.println("Queue1 (LinkedList) contents: " + queue1);
         System.out.println("Queue1 size: " + queue1.size());
@@ -38,7 +29,7 @@ public static void main(String[] args) {
         System.out.println("Peeking head element: " + queue1.peek());
 
 
-        // ---------------- Queue with ArrayBlockingQueue ----------------
+        // Queue with ArrayBlockingQueue
         // ArrayBlockingQueue is a bounded blocking queue with fixed capacity.
         Queue<Integer> queue2 = new ArrayBlockingQueue<>(2);
 
@@ -56,6 +47,16 @@ public static void main(String[] args) {
 }
 
 /*
+QueueInterface
+This class demonstrates how the Queue interface works in Java
+
+using two implementations:
+1. LinkedList (unbounded queue).
+2. ArrayBlockingQueue (bounded queue with fixed capacity).
+
+Queue follows FIFO (First In, First Out).
+Key methods: add(), offer(), remove(), poll(), element(), peek().
+
 1. Queue Interface:
    - Part of java.util package.
    - Represents a collection designed for holding elements prior to processing (FIFO).
@@ -111,5 +112,4 @@ ASCII Example (FIFO):
 Enqueue 1: [1]
 Enqueue 2: [1,2]
 Offer 3: fails (capacity full) → [1,2]
-
 */