import java.util.Iterator;
import java.util.NoSuchElementException;

public class FIFOListe<T> implements Iterable<T> {
    private Node hode;
    private Node hale;

    private class Node {
        private Node neste;
        private T verdi;

        Node(T v) {
            verdi = v;
        }
    }
    
    public int storrelse () {
        Node tmp = hode;
        int stoerrelse = 0;
        while (tmp != null) {
            stoerrelse++;
            tmp = tmp.neste;
        }
        return stoerrelse;
    }

    public boolean erTom () {
        return hode == null;
    }

    public void leggTil(T t) {
        Node ny = new Node(t);
        if (erTom())
            hode = ny;
        else
            hale.neste = ny;
        hale = ny;
    }

    public void fjernAlt() {
        hode = hale = null;
    }

    public T pop() {
        if (erTom()) 
            return null;
        Node ut = hode;
        if (hode == hale)
            fjernAlt();
        else
            hode = hode.neste;
        return ut.verdi;
    }

    public void skrivUtListe () {
        String string = "[ ";
        for (T t : this) {
            string += t.toString() + " ";
        }
        System.out.println(string + "]");
    }

    @Override
    public Iterator<T> iterator() {
        return new FIFOIterator();
    }

    private class FIFOIterator implements Iterator<T> {
        Node denne = hode;

        @Override
        public boolean hasNext() {
            return denne != null;
        }

        @Override
        public T next() {
            if (!hasNext()) throw new NoSuchElementException("next");
            Node tmp = denne;
            denne = denne.neste;
            return tmp.verdi;
        }
    }

    public static void main(String[] args) {
        FIFOListe<Integer> liste = new FIFOListe<>();
        liste.leggTil(1);
        liste.leggTil(2);
        liste.leggTil(3);
        liste.leggTil(4);
        liste.leggTil(5);
        liste.pop();
        liste.pop();
        liste.skrivUtListe();
    }
}