Answers for "onpressed flutter"

flutter navigate to new screen

// Within the `FirstRoute` widget
onPressed: () {
  Navigator.push(
    context,
    MaterialPageRoute(builder: (context) => SecondRoute()),
  );
}

onpressed pass context flutter

FloatingActionButton(
      onPressed: () => _showAddingDialog(context),
  ),
  
  Future _showAddingDialog(BuildContext context) {
  // ...
  }