public class NumberDisplay
{
    private int limit;
    private int value;

    public NumberDisplay(int rollOverLimit)
    {
        limit = rollOverLimit;
        value = 0;
    }

    public int getValue()
    {
        return value;
    }

    public void setValue(int replacementValue)
    {
        if((replacementValue >= 0) &&
                (replacementValue < limit)) {
                    value = replacementValue;
                }
    }

    public String getDisplayValue()
    {
        if(value < 10) {
            return "0" +value ;
        }
        else {
            return "" +value ;
        }
    }

    public void increment()
    {
        value = (value + 1) % limit;
    }
}