用于进行测试的类ContactInfo：

public class ContactInfo {
    public ContactInfo() {
    }
    public ContactInfo(int id, string name,
        DateTime date, string subject, double con) {
        this.id = id;
        this.name = name;
        this.date = date;
        this.subject = subject;
        this.concentration = con;
    }

    private int id;

    public int Id {
        get { return id; }
        set { id = value; }
    }
    private string name;

    public string Name {
        get { return name; }
        set { name = value; }
    }
    private DateTime date;

    public DateTime Date {
        get { return date; }
        set { date = value; }
    }
    private string subject;

    public string Subject {
        get { return subject; }
        set { subject = value; }
    }
    private double concentration;

    public double Concentration {
        get { return concentration; }
        set { concentration = value; }
    }

}

此类描述了通信录中的记录，只包含比较简单的方法，在此不详细讨论，然后介绍两个用于排序比较的类：

/// <summary>
    /// reusable custom DataRow comparer implementation, can be used to sort DataTables
    /// </summary>
    public class DataRowComparer : IComparer {
        ListSortDirection direction;
        int columnIndex;

        public DataRowComparer(int columnIndex, ListSortDirection direction) {
            this.columnIndex = columnIndex;
            this.direction = direction;
        }

        #region IComparer Members

        public int Compare(object x, object y) {

            DataRow obj1 = (DataRow)x;
            DataRow obj2 = (DataRow)y;
            return string.Compare(obj1[columnIndex].ToString(), 
                obj2[columnIndex].ToString()) * (direction == ListSortDirection.Ascending ? 1 : -1);
        }
        #endregion
    }

    // custom object comparer implementation
    public class ContactInfoComparer : IComparer {
        private int propertyIndex;
        ListSortDirection direction;

        public ContactInfoComparer(int propertyIndex, ListSortDirection direction) {
            this.propertyIndex = propertyIndex;
            this.direction = direction;
        }

        #region IComparer Members

        public int Compare(object x, object y) {
            ContactInfo obj1 = (ContactInfo)x;
            ContactInfo obj2 = (ContactInfo)y;

            switch (propertyIndex) {
                case 1:
                    return CompareStrings(obj1.Name, obj2.Name);
                case 2:
                    return CompareDates(obj1.Date, obj2.Date);
                case 3:
                    return CompareStrings(obj1.Subject, obj2.Subject);
                case 4:
                    return CompareNumbers(obj1.Concentration, obj2.Concentration);
                default:
                    return CompareNumbers((double)obj1.Id, (double)obj2.Id);
            }
        }
        #endregion

        private int CompareStrings(string val1, string val2) {
            return string.Compare(val1, val2) * 
                (direction == ListSortDirection.Ascending ? 1 : -1);
        }

        private int CompareDates(DateTime val1, DateTime val2) {
            if (val1 > val2) return (direction == ListSortDirection.Ascending ? 1 : -1);
            if (val1 < val2) return (direction == ListSortDirection.Ascending ? -1 : 1);
            return 0;
        }

        private int CompareNumbers(double val1, double val2) {
            if (val1 > val2) return (direction == ListSortDirection.Ascending ? 1 : -1);
            if (val1 < val2) return (direction == ListSortDirection.Ascending ? -1 : 1);
            return 0;
        }
    }