var keyA = UniqueKey(); var keyB = UniqueKey(); var keyC = UniqueKey(); var keyD = UniqueKey(); List widgetList = List(); widgetList.add(WidgetA(key: keyA)); widgetList.add(WidgetB(key: keyB)); widgetList.add(WidgetC(key: keyC)); widgetList.add(WidgetD(key: keyD)); Widget activeWidget = widgetList.firstWhere((x) => x.key == keyB);