public class BubbleSort : SortBase    {        public BubbleSort(int num, int[] arr):            base(num,arr)        {         }        public override int[] Sort()        {            int tmp;            for (int i = _arr.Length-1; i >= 0; i--)            {                for (int j = 0; j < i; j++)                {                    if (_arr[j + 1] < _arr[j])                    {                        tmp = _arr[j];                        _arr[j] = _arr[j + 1];                        _arr[j + 1] = tmp;                    }                }            }            return _arr;        }    }    public abstract class SortBase    {        protected int _num;        protected int[] _arr;        public abstract int[] Sort();        public SortBase(int num, int[] arr)        {            _num = num;            _arr = arr;        }        public virtual string GetResult()        {            int[] _result=Sort();            string ss = "结果为：";            for (int i = 0; i < _result.Length; i++)            {                ss += _result[i].ToString() + " ";            }            return ss;        }    }