how to use expended widget flutter code example

Example 1: conditionalstatement in widget flutter

Container(
  color: Colors.white,
  child: ('condition')
  ? Widget1(...)
  : Widget2(...)
)

Example 2: how to make reusable widget in flutter

Widget buildListContainer(BuildContext context,Widget list) {
    return Container(
      height: 300,
      child: ,
    );
  }