How To Detect When An Animation Has Ended In Flutter App

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() {
    return new MyHomePageState();
  }
}

class MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
  AnimationController animationController;
  Animation<double> animation;
  GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  void initState() {
    super.initState();
    animationController = AnimationController(
      vsync: this,
      duration: Duration(seconds: 5),
    )
      ..addListener(() => setState(() {}));

    animation = Tween<double>(
      begin: 50.0,
      end: 120.0,
    ).animate(animationController);

    animationController.forward();

    animation.addStatusListener((status) {
      if (status == AnimationStatus.completed) {
        scaffoldKey.currentState.showSnackBar(SnackBar(
          content: Text("Animation has ended"),
        ));
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: scaffoldKey,
      appBar: AppBar(
        backgroundColor: Colors.cyan,
          title: Text("Detect End Of An Animation"
          )),
      body: Center(
        child: Container(
          color: Colors.cyan,
          height: animation.value,
          width: animation.value,
        ),
      ),
    );
  }
}