LinkedStack

/**
 * A linked implementation of the Stack interface.
 */
public class LinkedStack<T> implements Stack<T> {

    private static class Node<T> {
        private T data;
        private Node<T> next;

        public Node(T data) {
            this.data = data;
            this.next = null;
        }
    }

    private Node<T> top;
    private int size;

    /**
     * Constructs an empty LinkedStack.
     */
    public LinkedStack() {
        top = null;
        size = 0;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void push(T element) {
        Node<T> newNode = new Node<>(element);
        newNode.next = top;
        top = newNode;
        size++;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public T pop() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        T element = top.data;
        top = top.next;
        size--;
        return element;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public T peek() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        return top.data;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int size() {
        return size;
    }

}