class constructor after inheritance - flutter

Question

i'm new to flutter i can't get the constructor to work which is in comment,
but the other constructor works, why? thank you
import 'package:flutter/material.dart';
import 'package:photo_view/photo_view.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: ImageEditor()
// child: PhotoView(imageProvider: AssetImage("Assets/img/carte.png"),)
);
}
}
class ImageEditor extends PhotoView {
// ignore: missing_required_param
ImageEditor():super(imageProvider: AssetImage("Assets/img/carte.png"),){
init();
}
//ImageEditor(){
// super(imageProvider: AssetImage("Assets/img/carte.png"),);
// init()
// }
void init(){
if(imageProvider!=null) {
print("il y a peut etre moyen de dessiner sur l'image");}
}
}

Answer 1

This is what you call a super constructor.
ImageEditor():super(imageProvider: AssetImage("Assets/img/carte.png")){
init();
}
Normally, a subclass can inherit all the variables and function from the parent class(using the extends) keyword, but you cannot access its constructor.
Using the : super() argument, you can however call the constructor from the parent class. You can only do it that way, that is simply the syntax.
Example:
class Class1 {
Class1(String name) {
print("Hello $name");
}
}
class Class2 extends Class1 {
Class2() : super("Tom") { //the name from above
print("Hello World");
}
}
void main() {
Class2 test = new Class2();
}
The output would be(in that order):
Hello Tom
Hello World