Implementing Queue using linked list in Java

Queue is a first in first out, last in last out data structure. It’s like people queuing up for getting in to a restaurant. In the following queue implementation, it uses linked list. There is the method add for adding an object, and there is the method remove for removing an object off the queue, as well as some other utility methods such as peek, size, isEmpty.

public class MyQueue<V> {
	private class Node<V> {
		V v;
		Node next;
		public Node(V v) {
			this.v  = v;
		}
	}
	
	private int size;
	private Node<V> head;
	private Node<V> tail;
	
	public MyQueue() {
		size = 0;
		head = null;
		tail = null;
	}
	
	public int size() {
		return size;
	}
	
	public boolean isEmpty() {
		return size == 0;
	}
	
	
	public void add(V v) {
		if (head == null) {
			head = new Node(v);
			tail = head;
		} else {
			tail.next = new Node(v);
			tail = tail.next;
		}
		
		size++;
	}
	
	public V remove() {
		if (size == 0) return null;
		
		V v = head.v;
		head = head.next;
		size--;
		
		return v;
	}
	
	
	public V peek() {
		if (size == 0) return null;
		
		V v = head.v;
		
		return v;
	}
	
	
	
	
	public static void main(String args[]) {
		MyQueue myQueue = new MyQueue();
		myQueue.add(1);
		myQueue.add(2);
		myQueue.add(3);
		System.out.println("Expected size 3, Actual size: " + myQueue.size());
		
		Integer i = (Integer) myQueue.remove();
		System.out.println("Expected size 2, Actual size: " + myQueue.size());
		System.out.println("Expected removed value 1, Actual removed value: " + i);
		
		i = (Integer) myQueue.remove();
		System.out.println("Expected removed value 2, Actual removed value: " + i);
		
		i = (Integer) myQueue.remove();
		System.out.println("Expected removed value 3, Actual removed value: " + i);
		
		System.out.println("Expected size 0, Actual size: " + myQueue.size());
		
		
		myQueue.add(1);
		myQueue.add(2);
		myQueue.add(3);
		i = (Integer) myQueue.peek();
		System.out.println("Expected size 3, Actual size: " + myQueue.size());
		System.out.println("Expected peeked value 1, Actual peeked value: " + i);
		
	}
	
	
}

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