package myUtil;

public class LStack<T> extends java.lang.Object implements Stack<T>
{
    private Node<T> top = null;

    public LStack(){

    }

    public T push(T item){
        top = new Node(item, top);
        return item;
    }
    public T pop(){
        T removed = top.getData();
        top.setNext(top.getNext());
        return removed;
    }
    public T peek(){
        return this.top.getData();
    }
    public boolean empty(){
        if (this.size() == 0){
            return true;
        }else{
            return false;
        }
    }
    public int size(){
        if (top == null){
            return 0;
        }
          int count = 1;
          Node<T> next = top;
          while (next.hasNext()){
            count++;
            next = next.getNext();
          }
          return count;
        }
    }
    class Node<T> {
        private T data;
        private Node<T> next;

        public Node(T data, Node<T> next) {
            this.data = data;
            this.next = next;
        }

        public boolean hasNext() {
            return this.next != null;
        }

        public Node<T> getNext() {
            return this.next;
        }

        public void setNext(Node<T> next) {
            this.next = next;
        }

        public T getData() {
            return this.data;
        }

        public void setData(T data) {
            this.data = data;
        }
}