butts.java

package LinkedList;

public class DoublyLinkedList<AnyType> {

	private class Node {
		public AnyType data;
		Node next;
		Node prev;

		public Node(AnyType data) {
			this.data = data;
		}
	}

	public class Iterator { 

		int current;
		DoublyLinkedList<AnyType> list;

		public Iterator(int current, DoublyLinkedList<AnyType> list) {
			this.current = current;
			this.list = list;
		}

		public boolean valid() {
			if(current < list.size()) {
				return true;
			} else {
				return false;
			}
		}

		public void next() {
			if(current+1 < list.size()) {
				current += 1;
			}
		}

		public void prev() {
			if(current-1 > 0) {
				current -= 1;
			}
		}

		public AnyType getData() {
			if(this.valid()) {
				// iteration = 0;
				// cNode = list.head;
				// while(iteration != current) {
				// 	iteration += 1;
				// 	cNode = cNode.next;
				// }
				Node cNode = index();
				return cNode.data;
			} else {
				return null;
			}
		}

		public void remove() {
			if(this.valid()) {
				// iteration = 0;
				// cNode = list.head;
				// while(iteration != current) {
				// 	iteration += 1;
				// 	cNode = cNode.next;
				// }
				Node cNode = index();
				cNode.prev.next = cNode.next;
			}
		}

		public void insert(AnyType data) {
			Node cNode = index();
			Node newNode = new Node(data);
			newNode.next = cNode.next;
			cNode.next = newNode;
		}

		private Node index() {
			int iteration = 0;
			Node cNode = list.head;
			while(iteration != current) {
				iteration += 1;
				cNode = cNode.next;
			}
			return cNode;
		}

	}

	Node head = new Node(null);

	//CONSTRUCTOR
	public DoublyLinkedList() {

	}

	//Adds a new Node to the front of the list
	void add(AnyType data) {
		Node newnode = new Node(data);
		newnode.next = head;
		head.prev = newnode;
		head = newnode;
	}

	//Removes the first Node with the given data from the list
	void remove(AnyType data) {
		Node cNode = head;
		while(cNode.data != data && cNode.data != null) {
			cNode = cNode.next;
		}
		if(cNode.data == data) {
			cNode.prev.next = cNode.next;
		}

	}

	public int size() {
		int listSize = 0;
		Node cNode = head;
		while(cNode.data != null) {
			listSize += 1;
			cNode = cNode.next;
		}
		return listSize;
	}

	public Iterator first() {
		return new Iterator(0, this);
	}

	public Iterator last() {
		int iteration = 0;
		Node cNode = head;
		while(cNode != null) {
			cNode = cNode.next;
			iteration += 1;
		}
		return new Iterator(iteration, this);
	}

	public Iterator find(AnyType data) {
		int iteration = 0;
		Node cNode = head;
		while(cNode.data != data && cNode.data != null) {
			cNode = cNode.next;
			iteration += 1;
		}
		if(cNode.data == data) {
			return new Iterator(iteration, this);
		} else { 
			return new Iterator(-1, this);
		}
	}

	
}