public class Revolver {

    private static Revolver[] instance = new Revolver[6];
    private static int nextInstanceNumber = 0;

    private Revolver() {
    }

    public static Revolver nextInstance() {
        if (nextInstanceNumber == 6) {
            nextInstanceNumber = 0;
        }
        if (instance[nextInstanceNumber] == null){
            System.out.println("Creating new instance");
            instance[nextInstanceNumber] = new Revolver();
        }
        return instance[nextInstanceNumber++];
    }

    public static int getNextInstanceNumber(){
        return nextInstanceNumber;
    }
}

public class Main {

    public static void main(String[] args){
        Revolver revolver = Revolver.nextInstance();
        System.out.println(revolver.getNextInstanceNumber() - 1);
        for (int i=0; i<15; i++){
            revolver = Revolver.nextInstance();
            System.out.println(revolver.getNextInstanceNumber() - 1);
        }
    }

}