Flutter - TextField border color

 

Change by:

focusedBorder:
            UnderlineInputBorder(borderSide: BorderSide(color: keyColor)),
      ),

    return TextField(
      autofocus: true,
      controller: control,
      decoration: InputDecoration(
        hintText: txt,
        hintStyle: TextStyle(color: keyColor.withOpacity(0.5)),
        focusedBorder:
            UnderlineInputBorder(borderSide: BorderSide(color: keyColor)),
      ),
      onChanged: func,
    );
  }
}

//you can alse change the focusColor: