my english is poor
forgive me
import 'package:flutter/material.dart';
class TestBox extends StatefulWidget {
final Color color;
final Duration delay;
const TestBox({
Key? key,
this.color = Colors.red,
this.delay = const Duration(seconds: 5),
}) : super(key: key);
@override
_TestBoxState createState() => _TestBoxState();
}
class _TestBoxState extends State<TestBox> {
String? label;
@override
void initState() {
initialMembers();
super.initState();
}
void initialMembers() async {
label = await fetchLabel();
if (mounted) setState(() {});
/// don't worry
/// if `(!mounted)`, means wen `build` calld
/// the label already has the newest value
}
Future<String> fetchLabel() async {
await Future.delayed(widget.delay);
print('fetchLabel call');
return 'from fetchLabel()';
}
@override
Widget build(BuildContext context) {
return AnimatedContainer(
margin: EdgeInsets.symmetric(vertical: 12),
duration: Duration(milliseconds: 500),
width: 220,
height: 120,
color: label == null ? Colors.white : widget.color,
child: Center(
child: Text(label ?? 'fetching...'),
),
);
}
}
Column(
children: [
TestBox(
delay: Duration(seconds: 1),
color: Colors.green,
),
TestBox(
delay: Duration(seconds: 3),
color: Colors.yellow,
),
TestBox(
delay: Duration(seconds: 5),
color: Colors.red,
),
],
),