//
//	P.127
//	A string linked list class, based on the string list node class
//

class LinkedList
{
	private ListNode head;
	public LinkedList() { head = null;  }
	public void insert(String addData)
	{ head = new ListNode(addData, head); }
	public void print()	// p.127 showList
	{
		ListNode position = head;
		while(position!= null)
		{
			System.out.print(position.getData() + " ");
			position = position.getLink();
		}
		System.out.println();
	}
	public void delete()	// p.128 deleteHeadNode
	{
		if(head!=null)
			head = head.getLink();
	}
	public int length()
	{
		int count = 0;
		ListNode position = head;
		while(position!=null)
		{
			count ++;
			position = position.getLink();
		}
		return count;
	}
	public boolean onList(String target)
	{	return find(target)!=null;  }
	private ListNode find(String target)
	{
		boolean found=false;
		ListNode position=head;
		while(position!=null && !found)
		{
			String dataAtPosition = position.getData();
			if(dataAtPosition.equals(target))
				found = true;
			else
				position=position.getLink();
		}
		return position;
	}
	public static void main(String[] args)
	{
		LinkedList me = new LinkedList();
		me.insert("ODU");
		me.insert("VWC");
		me.insert("UVA");
		me.print();
		me.delete();
		me.print();
		System.out.println("length = " + me.length());
		// Q: find "VWC" if it is on the list?
		if(me.onList("VWC")) System.out.println("VWC is on the list.");
		else	System.out.println("VWC is not on the list");
		me.insert("Harvard");
		System.out.println("length = " + me.length());

		System.out.println("\n\nDone.\n\n");
	}
}