'宣言 Protected Overrides Sub InsertItem( _ ByVal index As Integer, _ ByVal item As IHoliday _ )
'宣言
Protected Overrides Sub InsertItem( _ ByVal index As Integer, _ ByVal item As IHoliday _ )
protected override void InsertItem( int index, IHoliday item )
HolidayCollection クラス HolidayCollection メンバ