flutter checkbox doesn't work

Question

I want to build a checkbox with CheckboxListTile inside this widget dialog but when I tap the checkbox the checked on the checkbox doesn't change.

This is my code:

Future<Null> _showGroupDialog(BuildContext context) async {
    await showDialog(
        context: context,
        builder: (BuildContext dialogContext) =>
            Dialog(child: _buildCheckboxGroups(context)));
}

Widget _buildCheckboxGroups(BuildContext context) {
    List<Widget> childrens = List.generate(_groups.length, (index) {
      return CheckboxListTile(
        title: Text(_groups[index].name),
        value: _groups[index].checked,
        onChanged: (bool val) {
          setState(() {
            _groups[index].checked = val;
          });
        },
      );
    });

    return Container(
        child: Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: childrens,
    ));
}

Btw, the onChange method is invoked when I tap the checkbox. Can anyone solve this?

See github.com/flutter/flutter/issues/15194 - you are calling setState to update the widget that built the dialog, but not the dialog itself. — Jonah Williams
– Jonah Williams, Commented Jul 29, 2018 at 17:34

lavish · Accepted Answer · 2018-11-20 20:06:03Z

3

class _MyHomePageState extends State<MyHomePage>{

 //<Here you have to set default value for _groups[index].checked to false/true>
 @override
 Widget _buildCheckboxGroups(BuildContext context) {
  List<Widget> childrens = List.generate(_groups.length, (index) {
    return CheckboxListTile(
    title: Text(_groups[index].name),
    value: _groups[index].checked,
    onChanged: (bool val) {
      setState(() {
        _groups[index].checked = val;
      });
    },
  );
});}

Working Example is given below

class _MyHomePageState extends State<MyHomePage> {
 bool flagWarranty=false;
 @override
 Widget build(BuildContext context) {
  return Scaffold(
  appBar: AppBar(title: Text(widget.title)),
  body: new Container(
      padding: new EdgeInsets.all(20.0),
      child: new Form(
        key: this._formKey,
        child: new ListView(
          children: <Widget>[
              new Checkbox(
              value: flagWarranty,
              onChanged: (bool value) {
                setState((
                    ) {
                  flagWarranty=value;
                });
              },
            )
       ],),)));
 }}

answered Nov 20, 2018 at 20:06

lavish

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2 Comments

Abed Putra Over a year ago

Please always add descriptions about your code. Thank you.

Stefan Brinkmann Over a year ago

since onChecked requires a nullable bool? this example doesn`t even pass the syntax check.

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