constructor for stateful widget flutter code example

Example 1: send params to stateful widget

class Screen1 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Screen2(userId: "89d6db7e-7469-4888-9fac-38c300628ff1") // sends the value
    );
  }
}

class Screen2 extends StatefulWidget {
  final String userId; // receives the value

  Screen2({ Key key, this.userId }): super(key: key);

  @override
  _Screen2State createState() => _Screen2State();
}

class _Screen2State extends State {
  @override
  Widget build(BuildContext context) {
    return Text(widget.userId); // uses the value
  }
}

Example 2: flutter stateful widget

class YellowBird extends StatefulWidget {
  const YellowBird({ Key key }) : super(key: key);

  @override
  _YellowBirdState createState() => _YellowBirdState();
}

class _YellowBirdState extends State {
  @override
  Widget build(BuildContext context) {
    return Container(color: const Color(0xFFFFE306));
  }
}

Example 3: make stateful widget flutter

class MyClass extends StatefulWidget {
	@override
    MyClassState createState() => new MyClassState();
}

class MyClassState extends State {
	//Widgets and other code here
}

Example 4: flutter constructor in statefull widget

STATEFUL WIDGET CONSTRUCTOR

class ServerIpText extends StatefulWidget {
  final String serverIP;

  const ServerIpText ({ Key key, this.serverIP }): super(key: key);

  @override
  _ServerIpTextState createState() => _ServerIpTextState();
}

class _ServerIpTextState extends State {
  @override
  Widget build(BuildContext context) {
    return Text(widget.serverIP);
  }
}

class AnotherClass extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: ServerIpText(serverIP: "127.0.0.1")
    );
  }
}