// Page 247-248

public class Linkedlist<T>
{
	private ListNode<T> head;
	public Linkedlist()
	{	head = null; 	}
	public void print()
	{
		ListNode<T> position = head;
		while(position != null)
		{
			System.out.print(position.getData() + " ");
			position = position.getLink();
		}
		System.out.println();
	}
	public int length()
	{
		int count = 0;
		ListNode<T> position = head;
		while(position != null)
		{
			count ++;
			position = position.getLink();
		}
		return count;
	}
	public void insertTop(T addData)
	{	head = new ListNode<T>(addData, head);	}
	public void removeTop()
	{
		if(head != null)
			head = head.getLink();
		else
		{
			System.out.println("An empty list.");
			System.exit(0);
		}
	}
}