Why hot reload in flutter is influencing static variable incremented inside build method?

Question

I am trying the following code and while hot reloading it is incrementing static variable checkIfIncremented variable. Please someone explain me why is it so ??

import 'package:flutter/material.dart';
void main()=>runApp(MaterialApp(
  home: TrialApp(),
));
class TrialApp extends StatefulWidget {

  @override
  _TrialAppState createState() => _TrialAppState();
}

class _TrialAppState extends State<TrialApp> {
  static int checkIfIncremented = 0;
  @override
  Widget build(BuildContext context) {
    checkIfIncremented++;
    return Scaffold(
      body: Center(
        child: Text("This variable is getting incremented after each hot reload : $checkIfIncremented"),
      ),
    );
  }
}

Solution

This problem is due to the fact that each time you hot reload your program, the build method runs automatically. so you should avoid using checkIfIncremented++; inside this function. I am not sure why you use this code and what is your purpose, but you can use this code if you want to incrementcheckIfIncremented only at the first load:

bool firstLoad = true;

 @override
void didChangeDependencies() {
  super.didChangeDependencies();
  if(firstLoad){
     checkIfIncremented++;
     firstLoad = false;
     setState((){});
  }
}

Comments

[pskink]

beacuse if you hot reload the build method has to be called - otherwise you would not see any changes made by you

[pskink]

read api.flutter.dev/flutter/widgets/State/build.html for more info on how build method should be implemented

[pskink]

sure, your welcome

[Rontu Barhoi]

Thanks a lot for the explanation. I was learning how hot reload influences different states so tried this code to check if we can update the screen every time by hot reloading and look at the effect. Thanks.