Fade In Fade Out Animation

import "package:flutter/material.dart";

void main()
{
  runApp(const MyApp());
}
class MyApp extends StatelessWidget
{
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Fade in Fade out",
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        // primarySwatch: Colors.grey,
      ),
      home: const FadePractice(),
    );
  }
}
class FadePractice extends StatefulWidget
{
  const FadePractice({super.key});
  @override
  State<FadePractice> createState()
  {
    return FadePracticeState();
  }
}
class FadePracticeState extends State<FadePractice>
{
  bool visible = true;
  bool visible2 = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Fade in Fade out"),
        centerTitle: true,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            AnimatedOpacity(
              opacity: visible ? 1.0 : 0.0,
              duration: const Duration(seconds: 1),
              child: Container(
                width: 200.0,
                height: 200.0,
                color: Colors.green,
              ),
            ),
            AnimatedOpacity(
              opacity: visible2 ? 1.0 : 0.0,
              duration: const Duration(seconds: 1),
              child: Container(
                width: 200.0,
                height: 200.0,
                child: Image.asset("assets/images/Lord-Hanuman.jpg"),
              ),
            ),
          ],
        ),
      ),
      floatingActionButton: Row(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          FloatingActionButton(
            onPressed: () {
              setState(() {
                visible = !visible;
              },);
            },
            shape: OutlineInputBorder(
              borderRadius: BorderRadius.circular(30.0),
            ),
            backgroundColor: Colors.blue,
            child: const Icon(Icons.add, color: Colors.white, size: 30.0),
          ),
          const SizedBox(width: 20.0),
          FloatingActionButton(
            onPressed: () {
              setState(() {
                visible2 = !visible2;
              },);
            },
            shape: OutlineInputBorder(
              borderSide: BorderSide(color: Colors.yellow),
            ),
            backgroundColor: Colors.brown,
            child: const Icon(Icons.remove, color: Colors.white, size: 30.0),
          ),
        ],
      ),
    );
  }
}