edt04-ej4

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

            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 String toString() {
                return this.item.toString();
            }
        }
        @Override
        public Iterator<E> iterator() {
            return new MyIterator(this.head);
        }
        private class MyIterator implements Iterator<E> {
            private Node actual;

            public MyIterator(Node inicio) {
                this.actual = inicio;
            }

            @Override
            public boolean hasNext() {
                return this.actual != null;
            }

            @Override
            public E next() {
                if (!this.hasNext()) {
                    throw new RuntimeException("La lista está vacía...");
                }
                E item = this.actual.item;
                this.actual = this.actual.next;
                return item;
            }
        }
}
}
public class List<E> {
private Node<E> head;
private Node<E> tail;
int count;
public Node<E> getHead(){
return this.head;
}
public Node<E> getTail(){
return this.tail;
}
public boolean isEmpty() {
if (this.count == 0) {
return true;
}
return false;
}

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

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

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

public boolean Contains(E item) {
if (this.count==0) {
return false;
}
Node<E> nodo;
for (nodo = this.head; nodo.getNext() != null; nodo = nodo.getNext()) {
if (nodo.getItem().equals(item)) {
return true;
}
}
if (nodo.getItem().equals(item)) {
return true;
}
return false;
}

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

public E RemoveFromHead() {
if (this.count==0) {
throw new RuntimeException("Está vacío");
}else {
E aux = this.head.getItem();
this.head = this.head.getNext();
if(this.head==null) {
this.tail=null;
}
--this.count;
return aux;
}
}

public E RemoveFromTail() {

if (this.count==0) {
throw new RuntimeException("Está vacío");
}
E aux = this.tail.getItem();
if(this.head.next==null) {
this.head=this.tail=null;
}else {
Node<E> nodo = this.head;
for (; nodo.getNext() != null; nodo = nodo.getNext()) {}
this.tail=nodo;
this.tail.next=null;
}
--this.count;
return aux;
}

public String toString() {
if (this.count==0) {
throw new RuntimeException("Está vacío");
}else {
Node<E> nodo = this.head;
String str = "";
for (nodo=this.head; nodo.getNext() != null; nodo = nodo.getNext()) {
str += nodo.getItem().toString();
}
str += nodo.getItem().toString();
return str;
}
}
}

// Clase generica Cola con una Lista
public class Queue<E> {
List<E> lista;

public boolean isEmpty() {
return lista.isEmpty();
}

public E DeQueue() {
if(lista.isEmpty()) {
return null;
}else {
E obj = lista.RemoveFromHead();
return obj;
}
}

public void EnQueue(E elem) {
if(lista.isEmpty()) {
lista.AddToHead(elem);
}else {
lista.AddToTail(elem);
}
}

public E Peek() {
if(lista.isEmpty()) {
System.out.println("Esta vacia");
return null;
}else {
return lista.getHead().getItem();
}
}

public Queue() {
this.lista= new List<E>();
}
}