SP - Iterator Pattern

package ZITR1;
// Задатак RZITR1: Додати програм на месту три тачке како би се добила порука:
// Items:
// 4
// 2
// 1
// 5
// 3

class Client {
    Aggregate ag;
    Iterator it;

    Client(){
        ag=new ConcreteAggregate();
         it = new ConcreteIterator((ConcreteAggregate) ag);
     }

    public static void main(String args[]) {
        Client cl = new Client();
        cl.printItems();
    }
    void printItems() {
        System.out.println("Items:");
        it.First();
        while (it.IsEnd()) {
            System.out.println(it.currentItem());
            it.Next();
        }
  }}

abstract class  Aggregate{
    int n[];

    abstract Iterator createIterator();
    int getItem(int indeks) {return n[indeks];}
    int getItemsNumber(){return n.length;}
}

class ConcreteAggregate extends Aggregate   {
    ConcreteAggregate() { n = new int[5]; n[0]=4; n[1]=2; n[2]=1; n[3]=5; n[4]=3;}

    Iterator createIterator() { return new ConcreteIterator(this);}
}

abstract class Iterator{
    abstract void First();
    abstract void Next();
    abstract boolean IsEnd();
    abstract int currentItem();
}

class ConcreteIterator extends Iterator  {
  ConcreteAggregate ag;
  int indeks;

  ConcreteIterator(ConcreteAggregate ag1) {ag = ag1;}

  void First() {indeks = 0;}
  void Next() {indeks++;}
  boolean IsEnd () {return indeks < ag.getItemsNumber();}
  int currentItem() {return ag.getItem(indeks);}
}