Flutter List View error in building list view - dart

Question

I get an error while I'm building the ListView, At first I thought the API wasn't returning anything but I printed the movies variable in flutter and it consoled log the values.
Btw I'm trying to recreate this project:
https://github.com/mlabouardy/flutter-watchnow
The error I get is:
RangeError (index): Invalid value: Valid value range is empty: 0
This is the list view builder:
class TopMoviesState extends State<TopMovies> {
List<Movie> _movies = new List();
final _apiGatewayURL = "https://gfioehu47k.execute-api.us-west-1.amazonaws.com/staging/main";
Widget _fetchMovies() {
return new ListView.builder(
padding: const EdgeInsets.all(16.0),
itemBuilder: (context, i){
return new Card(
child: new Container(
height: 250.0,
child: new Padding(
padding: new EdgeInsets.all(2.0),
child: new Row(
children: <Widget>[
new Align(
child: new Hero(
child: new Image.network("https://image.tmdb.org/t/p/w500"+this._movies[i].getPoster()),
tag: this._movies[i].getTitle()
),
alignment: Alignment.center,
),
new Expanded(
child: new Stack(
children: <Widget>[
new Align(
child: new Text(
this._movies[i].getTitle(),
style: new TextStyle(fontSize: 11.0, fontWeight: FontWeight.bold),
),
alignment: Alignment.topCenter,
),
new Align(
child: new Padding(
padding: new EdgeInsets.all(4.0),
child: new Text(
this._movies[i].getOverview(),
maxLines: 8,
overflow: TextOverflow.ellipsis,
style: new TextStyle(fontSize: 12.0, fontStyle: FontStyle.italic)
)
),
alignment: Alignment.centerRight,
),
new Align(
child: new Text(
this._movies[i].getReleaseDate(),
style: new TextStyle(fontSize: 11.0, fontWeight: FontWeight.bold),
),
alignment: Alignment.bottomRight,
),
]
)
)
]
)
)
)
);
}
);
}
This is how I'm running through each value I'm getting from the API:
void _addMovie(dynamic movie){
this._movies.add(new Movie(
title: movie["title"],
overview: movie["overview"],
poster: movie["poster_path"],
releaseDate: movie["release_date"]
));
}
#override
void initState() {
super.initState();
http.get(this._apiGatewayURL)
.then((response) => response.body)
.then(json.decode)
.then((movies) {
movies.forEach(_addMovie);
});
}

Answer 1

You are not specifying an itemCount to ListView. So if you ever have enough space to display more then the number of items available, you'll try to access _movies at an invalid index. Resulting in this error.
Try to add
new ListView(
...
itemCount: _movie.length

Answer 2

you need to add item count
new ListView(
...
itemCount: _movie.length
without it ListView.Builder not know the position of list and and we are not showing the list according to position

Answer 3

Try to add the index of listview.builder,
Listview.builder is used for a very long or unknown set of lists, which you are doing correct.
Just count the number of values you are getting from the API response and add the index as a parameter.
For more reference, check this URL:
https://docs.flutter.io/flutter/widgets/ListView/ListView.builder.html