public class DataSetTester
{
    public static void main(String[] args)
    {
        DataSet ds1 = new DataSet();
        ds1.addValue(10);
        ds1.addValue(1);
        System.out.println(ds1.getSum());     // 11
        System.out.println(ds1.getAverage()); // 5.5

        DataSet ds2 = new DataSet(5);
        ds2.addValue(9);
        ds2.addValue(3);
        System.out.println(ds2.getSum());     // 17
        System.out.println(ds2.getAverage()); // 5.666...
    }
}