public class ClockDisplay
{
    private NumberDisplay hour;
    private NumberDisplay minute;

    public ClockDisplay()
    {
        hour = new NumberDisplay(23,23);
        minute = new NumberDisplay(59,56);
    }

    public void printTime()
    {
        System.out.println(hour.getValue() + ":" + minute.getValue());
    }

    public void nextMinute()
    {
        if(minute.getValue() == minute.getMax())
        {
            if(hour.getValue() == hour.getValue())
            {
                minute.forward();
                hour.forward();
            }
            else
            {
                minute.forward();
            }
        }
        else
        {
            minute.forward();
        }
    }
}