public class Queue<T> implements Iterable<T>{

private java.util.LinkedList<T> list = new java.util.LinkedList<T>();

public Queue(){}

public Queue(T data){

enqueue(data);

}

public int size(){

return list.size();

}

public boolean isEmpty(){

return size() == 0;

}

public T peek(){

if(isEmpty()) throw new RuntimeException('The queue is empty');

return list.peekFirst();

}

public T dequeue(){

if(isEmpty()) throw new RuntimeException('The queue is empty');

return list.removeFirst();

}

public void enqueue(T data){

list.addLast(data);

}

@Override public java.util.Iterator <T> iterator(){

return list.iterator();

}

}