TP4ej2_List

public class List<E> {
    private Node head;
    private int count;
    private Node tail;


    public boolean isEmpty() {
        return count <= 0;
    }

    public int getCount() {
        return this.count;
    }

    //Metodos
    public List() {
        this.head = null;
        this.count = 0;
        this.tail = null;
    }


    public void AddToHead(E item) {
        Node temp = new Node(item, this.head);
        if(this.count == 0) {
            this.tail = temp;
        }
        this.head = temp;
        ++this.count;
    }

    public void AddToTail(E item) {
        Node temp = new Node(item, null);
        if(this.count == 0) {
            this.head = temp;
        }
        else {
            this.tail.next = temp;
        }
        this.tail = temp;
        ++this.count;
    }



    public E RemoveFromHead() {
        if(this.count == 0) {
            throw new RuntimeException("La lista está vacia...");
        }
        E item = this.head.item;
        this.head = this.head.next;
        if(this.head == null) {
            this.tail = null;
        }
        --this.count;
        return item;
    }

    public E RemoveFromTail() {
        if(this.count == 0) {
            throw new RuntimeException("La lista está vacia...");
        }
        E item = this.tail.item;
        if(this.head.next == null) {
            this.head = this.tail = null;
        }
        else {
            Node skip = this.head;
            for( ; skip.next.next != null; skip = skip.next) { }
            this.tail = skip;
            this.tail.next = null;
        }
        --this.count;
        return item;
    }

    public void Mostrar() {
        for(Node skip = this.head; skip != null; skip = skip.next) {
            System.out.println(skip);
        }
    }


    private class Node {
        public E item;
        public Node next;

        //Getters & Setters
        public E getItem() {
            return item;
        }

        public void setItem(E item) {
            this.item = item;
        }

        public Node getNext() {
            return next;
        }

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

        //Metodos
        public Node() {
            this(null, null);
        }

        public Node(E item) {
            this(item, null);
        }

        public Node(E item, Node next) {
            this.item = item;
            this.next = next;
        }

        public Node(Node next) {
            this(null,next);
        }


        public String toString() {
            return this.item.toString();
        }

    }

}