CircularLinkedList

public class CircularLinkedList {
	private ListNode last;

	public CircularLinkedList() {
		last = null;
	}

	public boolean isEmpty() {
		return last == null;
	}

	public String toString() {
		String val = "";
		if (isEmpty()) {
			return "Error: Empty List";
		}
		ListNode curr = last.getNext();
		while (curr != last) {
			val += curr.getValue();
			curr = curr.getNext();
		}
		val += last.getValue();
		return val;
	}

	public int size() {
		int val = 0;
		if (isEmpty()) {
			return 0;
		}
		ListNode curr = last.getNext();
		while (curr != last) {
			val++;
			curr = curr.getNext();
		}
		return val+1;
	}

	public void addFirst(Object arg) {
		if (isEmpty()) {
			ListNode test = new ListNode(arg, last);
			test.setNext(test);
		}
		ListNode next = last.getNext();
		last.setNext(new ListNode(arg, next));
	}
	public Object removeFirst(Object arg) {
		if (isEmpty()) {
			return null;
		}
		ListNode first = last.getNext();
		if (last == first) {
			return first.getValue();
		}
		last.setNext(first.getNext());
		return first.getValue();
	}
	public void addLast(Object arg) {
		if (isEmpty()) {
			ListNode test = new ListNode(arg, last);
			test.setNext(test);
		}
		ListNode first = last.getNext();
		ListNode curr = first;
		while (curr != last) {
			curr = curr.getNext();
		}
		curr.setNext(new ListNode(arg, first));
	}
	public Object removeLast(Object arg) {
		if (isEmpty()) {
			return null;
		}
		ListNode first = last.getNext();
		if (last == first) {
			return first.getValue();
		}
		ListNode curr = first;
		while (curr.getNext() != last) {
			curr = curr.getNext();
		}
		curr.setNext(new ListNode(arg, first));
		return last;
	}

}