public class ChainePile<E> implements Pile<E> {

    private Chaine<E> lastChain;

    public ChainePile() {}

    @Override
    public E getFirst() {
        if (lastChain != null) {
            return lastChain.getValue();
        } else {
            return null;
        }
    }

    @Override
    public E pollFirst() {
        if (lastChain != null) {
            E value = lastChain.getValue();
            lastChain = lastChain.getNext();
            return value;
        } else {
            return null;
        }
    }

    @Override
    public void addFirst(E e) {
        Chaine<E> link = new Chaine<E>();
        link.setValue(e);
        link.setNext(lastChain);
        lastChain = link;
    }

    @Override
    public int size() {
        int count = 0;
        Chaine<E> curr = lastChain;
        while (curr != null) {
            curr = curr.getNext();
            count++;
        }

        return count;
    }
    
}