public class Auto {

    private int id;
    //private static int idC;

    public Auto(){
        id=Eventmanager.addAID();
        //idC++;
        //id=idC;
    }

    public void output(){
        System.out.println(id);
    }
}

public class Eventmanager {
    public static int autoid=0;
    public static int nutzerid=0;

    public static int addAID(){
        autoid++;
        return autoid;
    }

    public static int addNID(){
        nutzerid++;
        return nutzerid;
    }
}

public class Nutzer {

    private int id;
    //private static int idC;

    public Nutzer(){
        id=Eventmanager.addNID();
        //idC++;
        //id=idC;
    }

    public void output(){
        System.out.println(id);
    }
}

import java.util.ArrayList;

public class mainClass {
    public static void main(String[] ARGS){
        int d=10;

        ArrayList<Auto> aList = new ArrayList<>();
        ArrayList<Nutzer> nList = new ArrayList<>();

        for(int i=0;i<d;i++){
            aList.add(new Auto());
        }

        for(int i=0;i<d;i++){
            nList.add(new Nutzer());
        }

        iterate(aList);
        System.out.println();
        iterate(nList);

    }

    public static void iterate(ArrayList<?> list){
        for(Object obj:list){
            if(obj instanceof Auto){
                ((Auto) obj).output();
            }
            else{
                ((Nutzer) obj).output();
            }

        }
    }
}