I am new to flutter and decided to build a simple timer app, that counts the number of seconds that have gone by since it's start and it ends up showing the wrong time. The timer starts off with 0, then increments to 1 and, from there on out it seems as if it is increasing exponentially.
main.dart
import 'package:flutter/material.dart';
import 'app.dart';
void main() => runApp(App());
app.dart
import 'package:flutter/material.dart';
import 'package:async/async.dart';
import 'clock_widget.dart';
class App extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Timer",
home: Scaffold(
appBar: AppBar(
title: Text("Timer"),
centerTitle: true,
),
body: Row(
mainAxisSize: MainAxisSize.max,
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
ClockWidget(),
Text("seconds", style: TextStyle(fontWeight: FontWeight.bold, fontSize: 35),)
],
)
],
)
),
);
}
clock_widget.dart
import 'dart:async';
import 'package:flutter/material.dart';
class ClockWidget extends StatefulWidget {
@override
ClockWidgetState createState() => ClockWidgetState();
}
class ClockWidgetState extends State<ClockWidget> {
@override
int _secondCount = 0;
Widget build(BuildContext context) {
Timer.periodic(Duration(seconds: 1), (Timer t) => (setState(() {_secondCount+=1;})));
print("${_secondCount}");
return Text("${_secondCount}", style: TextStyle(fontSize: 75, color: Color.fromRGBO(30, 144, 255, 1)),);
}
}
I have tried numberous methods but to me this seemed like the simplest one and logically it seems correct. After every second setState is called which increments _secondsCount.
You are currently defining new
Timer
s every second. Each of these timers is incrementing the number of seconds.You want to define your
Timer
only once and outside of thebuild
method.initState
build
methodTimer
indispose
Here's an example: