how to make round circular button in flutter code example

Example 1: A circuler border button in flutter

Padding(  padding: EdgeInsets.only(left: 150.0, right: 0.0),  child: RaisedButton(    textColor: Colors.white,    color: Colors.black,    child: Text("Search"),    onPressed: () {},    shape: new RoundedRectangleBorder(      borderRadius: new BorderRadius.circular(30.0),    ),  ),)

Example 2: how to change the shape of a buton in flutter to cicular

RawMaterialButton(
  ...,
  shape: CircleBorder(),
)