textfield underline border Color In flutter code example
Example: change border color of TextField in flutter
TextFormField(
decoration: InputDecoration(
labelText: "Resevior Name",
fillColor: Colors.white,
focusedBorder:OutlineInputBorder(
borderSide: const BorderSide(color: Colors.white, width: 2.0),
borderRadius: BorderRadius.circular(25.0),
),
),
)