public class SingleList {

	SNode head = null;
	SNode tail = null;
	
	//Below is the Node class to be used for packets in
	//a singly linked list
	private class SNode {
		Packet p;  // packet reference
		SNode next;  //next pointer
		
		//Constructor for a Node, default
		private SNode (Packet p) {
			setPacket(p); this.next = null;
		}
		private void setNext(SNode s){ 
			this.next = s; 
		}
		private void setPacket (Packet p) {
			this.p = p;
		}
	}
	
	//pre - p is a valid packet
	//post - a new node containing p has been added to the
	//			end of the linked list
	public void addNode(Packet p){
		SNode s = new SNode(p);
		if (head ==null) {
			head = s;
			tail = s;
		} else {
			tail.setNext(s);
			tail = s;
		}	
	}	
	
	//post - if the list is empty, it returns "List empty\n"
	//			if the list is not empty, it adds each packet to string along with
	//			a \n after the packet
	public String  toString() {
		if (head == null)
			return "List empty\n";
		String sr = "";
		SNode s = head;
		while (s != null) {
			sr = sr + s.p + "\n";
			s = s.next;
		}
		return sr;
	}
	
	// Use this main to test your list
	public static void main (String[] args) {
		SingleList s1 = new SingleList();
		System.out.println (s1);
		Packet p1 = new Packet();
		p1.setPkPacketID(1);
		p1.setPkDestPort(0);
		p1.setPkServiceLevel(Packet.ServiceLevel.HIGH);
		p1.setPkPayload("asfasdf");
		s1.addNode(p1);
		System.out.println (s1);
		Packet p2 = new Packet();
		p2.setPkPacketID(2);
		p2.setPkDestPort(1);
		p2.setPkServiceLevel(Packet.ServiceLevel.NORMAL);
		p2.setPkPayload("asfasdf");
		s1.addNode(p2);
		System.out.println (s1);
	}
}