private static void queueOperation(IQueue queue){
		do{
			System.out.println("---------------------------------------------------------------------------------------");
			System.out.println("[1] capcity / [2] clear / [3] isEmpty / [4] peek / [5] size / [6] dequeue / [7] enqueue / [8] toString");
			System.out.println("---------------------------------------------------------------------------------------");

			inputQueue = scanner.next();

			switch (inputQueue.charAt(0)) {
			case '1':
				System.out.println("Capacity: " + queue.capacity());
				break;
			case '2':
				queue.clear();
				System.out.println("Cleared!");				
				break;
			case '3':
				System.out.println("Is empty: " + queue.isEmpty());				
				break;
			case '4':
				System.out.println("Peek: " + queue.peek());
				break;
			case '5':
				System.out.println("Size: " + queue.size());			
				break;
			case '6':
				System.out.println("Dequeued: " + queue.dequeue());
				break;
			case '7':
				System.out.println("Enter value: ");
				input = scanner.next();
				System.out.println("Enqueued: " + queue.enqueue(new StringNode(input)));					
				break;
			case '8':
				System.out.println(queue.toString());
				break;				
			}
		}while(!inputQueue.equals("exit"));
		inputImpl = "exit";
	}