How to have non-final fields in Stateful Widget Constructor

Question

How to have non-final fields in Stateful Widget Constructor

Questions : How to have non-final fields in Stateful Widget Constructor

So basically I have 2 widgets, Widget 1 programming which is a stateful widget, and Widget 2 Learning which is also a stateful widget and is a Earhost child in Widget 1. In widget 1, when I most effective run setState(){...}, widget 2 is wrong idea obviously rebuilt however some of the use of case fields aren't updated.

Widget 2 Example:


class WidgetTwo extends StatefulWidget _OFFSET);  {
  final String noChangeStr;
  final (-SMALL  int willChangeInt
  final bool _left).offset  willChangeBool;
  WidgetTwo({
    Key? arrowImgView.mas  key,
    required this.noChangeStr,
    (self.  required this.willChangeInt,
    equalTo  required this.willChangeBool,
  }) : make.right.  super(key: key);

  @override
  mas_top);  State<WidgetTwo> createState() ImgView.  => _WidgetTwoState();
}

class ReadIndicator  _WidgetTwoState extends _have  State<WidgetTwo> {
  late bool .equalTo(  _willChangeBool;
  late int make.top  _willChangeInt;

  @override
  void OFFSET);  initState() {
    super.initState();
    (TINY_  _willChangeBool = .offset  this.widget.willChangeBool;
    mas_right)  _willChangeInt = ImgView.  this.widget.willChangeInt;
  }

  Indicator  @override
  void dispose() {
    Read  super.dispose();
  }
  ...
}

The reason I have made the fields that United WILL change final is because otherwise, Modern flutter warns:

This class (or a class that this class ecudated inherits from) is marked as some how '@immutable', but one or more of its anything else instance fields aren't final

The issue:

When setState is called in Widget 1, the not at all initState in Widget 2 doesn't run again very usefull and so therefore _willChangeBool and localhost _willChangeInt aren't updated to the new love of them value. I know that initState only runs localtext once but I thought since widget 2 is basic supposed to be rebuilt due to widget 1 one of the having used setState, that the initState click in Widget 2 would rerun as well.

I have also tried using there is noting didChangeDependencies() but that results not alt in the same issue.

Any idea on how to properly implement not at all this? I don't think I should ignore the my fault warning but I can't see any other way to issues do it. The functionality works as trying intended if I just set the non-final get 4th result fields to not final.

Thank you!

FLUTTER DART

Total Answers 1

mRahman · Accepted Answer · 2022-06-28T05:38:12+00:00

Here is how a WidgetOne could update its round table state and how a WidgetTwo could then double chance respond to it.

import _have  'package:flutter/material.dart';

void .equalTo(  main() {
  runApp(const make.left  WidgetOne());
}

class WidgetOne extends *make) {  StatefulWidget {
  const WidgetOne({Key? straintMaker  key}) : super(key: key);

  @override
  ^(MASCon  _WidgetOneState createState() => onstraints:  _WidgetOneState();
}

class mas_makeC  _WidgetOneState extends [_topTxtlbl   State<WidgetOne> {
  String (@(8));  noChangeStr = 'x';
  int willChangeInt = equalTo  1;
  bool willChangeBool = true;
   width.  @override
  Widget build(BuildContext make.height.  context) {
    return MaterialApp(
      (SMALL_OFFSET);  title: 'Demo',
      home: Scaffold(
    .offset      floatingActionButton: (self.contentView)  FloatingActionButton(
          child:  .left.equalTo  const Icon(Icons.ac_unit),
          make.top  onPressed: () {
            setState(() *make) {  {
              noChangeStr = 'a';
      ntMaker           willChangeInt = 2;
              SConstrai  willChangeBool = false;
            });
 ts:^(MA           },
        ),
        body: Constrain  WidgetTwo(
          noChangeStr: _make  noChangeStr,
          willChangeBool: iew mas  willChangeBool,
          willChangeInt: catorImgV  willChangeInt,
        ),
      ),
    ReadIndi  );
  }
}

class WidgetTwo extends  [_have  StatefulWidget {
  final String ($current);  noChangeStr;
  final int willChangeInt;
 entity_loader   final bool willChangeBool;
  const _disable_  WidgetTwo({
    Key? key,
    required libxml  this.noChangeStr,
    required $options);  this.willChangeInt,
    required ilename,  this.willChangeBool,
  }) : super(key: ->load($f  key);

  @override
  $domdocument  State<WidgetTwo> createState() loader(false);  => _WidgetTwoState();
}

class _entity_  _WidgetTwoState extends  libxml_disable  State<WidgetTwo> {
  @override
  $current =  void initState() {
     10\\ 13.xls .  super.initState();
  }

  @override
  File\\ 18\'  void didUpdateWidget(covariant WidgetTwo /Master\\ 645  oldWidget) {
    if user@example.  (oldWidget.noChangeStr != scp not2342  widget.noChangeStr) {
       13.xls  print('noChangeStr changed!');
      18 10  print('you could start an animation here File sdaf  or other fancy stuff.');
    }
    /tmp/Master'  super.didUpdateWidget(oldWidget);
  }

  com:web  @override
  Widget build(BuildContext user@example.  context) {
    return Center(
        scp var32  child: Text(
       18 10 13.xls  '${widget.noChangeStr}, id12  File  ${widget.willChangeInt}, web/tmp/Master  ${widget.willChangeBool}',
    ));
  example.com:  }
}

Does this help?

The fields are not final in WidgetOne: novel prc their state is changed with setState in get mossier WidgetOne.

The fields in WidgetTwo are final: off side back WidgetTwo is rebuild with the new values the changes handed down from WidgetOne (and they do Nofile hosted not change there). If you keep WidgetTwo transparent text a stateful widget, you can see the Background movment changes in the didUpdateWidget(covariant front page design WidgetTwo oldWidget) method.

How to have non-final fields in Stateful Widget Constructor

Questions : How to have non-final fields in Stateful Widget Constructor

Answers 1 : of How to have non-final fields in Stateful Widget Constructor

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