ListView don't appear in the first time Flutter - android-studio

Question

My problem is that : The listview does not appear at the first launch of app but after a hot reload it appears.
It's the first time I meet this bug.
That's my code :
#override
Widget build(BuildContext context) {
return new Scaffold(
backgroundColor: Colors.black,
body: new ListView.builder(
itemCount: toutesLesCartes.length,
itemBuilder: (context, count) {
Carte carte = toutesLesCartes[count];
String nom = carte.nomCarte;
String image = carte.imageCarte;
return new Dismissible(
key: new Key(nom),
direction: DismissDirection.endToStart,
child: new Container(
margin: EdgeInsets.all(5.0),
child: new Card(
color: Colors.transparent,
elevation: 10.0,
child: new Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Image.network(image, width: 150.0, height: 150.0,),
new CustomText(nom, factor: 2.0,),
],
),
),
),
background: new Container(
padding: EdgeInsets.only(right: 20.0),
color: Colors.red,
child: new Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
new CustomText("Supprimer"),
new Icon(Icons.delete, color: Colors.white,)
],
),
),
onDismissed: (direction) {
setState(() {
toutesLesCartes.removeAt(count);
nombreCarteChoisiValeur--;
});
},
);
}
),
);
}
I have an idea but it's strange : before, I using the Visibility widget so it is possible that it comes from a possible "cache" of the application?
All that will look at this post and help me, thank you very much!
Have a nice day !

Answer 1

Likely because toutesLesCartes.length is 0.
you can check this using the debugger or display something when the length is 0 eg
#override
Widget build(BuildContext context) {
return new Scaffold(
backgroundColor: Colors.black,
body: new ListView.builder(
itemCount: toutesLesCartes.length, //* place breakpoint here
itemBuilder: (context, count) {
Carte carte = toutesLesCartes[count];
String nom = carte.nomCarte;
String image = carte.imageCarte;
if(toutesLesCartes == null || toutesLesCartes.length == 0){
return CircularProgressIndicator(); //you should see loading animation if list is empty
}
return new Dismissible(
key: new Key(nom),
direction: DismissDirection.endToStart,
child: new Container(
margin: EdgeInsets.all(5.0),
child: new Card(
color: Colors.transparent,
elevation: 10.0,
child: new Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Image.network(image, width: 150.0, height: 150.0,),
new CustomText(nom, factor: 2.0,),
],
),
),
),
background: new Container(
padding: EdgeInsets.only(right: 20.0),
color: Colors.red,
child: new Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
new CustomText("Supprimer"),
new Icon(Icons.delete, color: Colors.white,)
],
),
),
onDismissed: (direction) {
setState(() {
toutesLesCartes.removeAt(count);
nombreCarteChoisiValeur--;
});
},
);
}
),
);
}
The solution would be to use a FutureBuilder
Word of warning: The application will run the build method multiple times, it's good practice to place anything you don't want to be repeatedly called (like database calls) outside of the method.