public class DoubleList {
	
	private DNode head;

	private class DNode {
		private Packet p;
		private DNode prev;
		private DNode next;
		
		//This constructor is called to create a node to add to the list
		private DNode (Packet p, DNode prev, DNode next) {
			setPacket(p);
			setPrev(prev);
			setNext(next);
		}
		
		//This constructor is called to set up the head node
		private DNode() { 
			this.p = null; this.prev = this; this.next = this;
		}
		
		//setters
		private void setNext(DNode n){ 
			next = n; 
		}
		private DNode getNext () {
			return next;
		}
		private void setPrev(DNode p){ 
			prev = p; 
		}
		private DNode getPrev() {
			return prev;
		}
		private void setPacket (Packet p) {
			this.p = p;
		}
		private Packet getPacket() {
			return p;
		}
	}
	//Constructor called to initialize the doubly linked list
	public DoubleList() {
		System.out.println ("Default constructor not implemented yet");
	}

	//pre - doubly linked list has been created
	//post - boolean value returned whether there are nodes
	//			on the list other than head.
	public boolean isEmpty () {
		System.out.println ("isEmpty not implemented yet");
		return false;
	}
	
	//pre - doubly linked list has been created
	//post - returns null if the list is empty
	//			returns the packet in the first position of the list
	public Packet removeNode() {
		System.out.println ("removeNode not implemented yet");
		return null;
	}
	
	//pre - doubly linked list has been created
	//post - finds and removes a node from the list
	//			if a node containing the packetID is found,
	//			returns the pointer to the packet id
	//			If a node containing the packet id is not found, 
	//			Returns null.
	public Packet removeNode(int packetID){
		System.out.println ("removeNode(int) not implemented yet");	
		return null;
    }
	
	//pre - p is a valid packet
	//post - a node containing p has been added to the list.
	public void addNode (Packet p) {
		System.out.println ("addNode not implemented yet");	
	}
	
	//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() {
		System.out.println ("Default constructor not implemented yet");
    	return "";
	}
	//Use this space for test cases
	public static void main (String[] args) {
	}
}