5.AlerDialog

 void bookFlight(BuildContext context)
  {
    var alertDialog=AlertDialog(
      title: Text("Flight Booked successfully"),
      content: Text("have a pleasant Flight"),

    );
    showDialog(context: context,
    builder: (BuildContext context)=>alertDialog
    );
  }

class FlightBookButton extends StatelessWidget
{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      margin: EdgeInsets.only(top: 30.0),
      width: 250.0,
      height: 60.0,
      child: RaisedButton(
          child: Text("Book Your Ticket",
          style: TextStyle(
            fontSize: 16.0
          ),),
          color: Colors.deepOrange,
          elevation: 6.0,
          onPressed:() => bookFlight(context)
      ),
    );
  }