Flutter: auto complete widget from reading items from text file - flutter

Question

I am trying to implement Autocomplete Widget and the items are present in a text file. While reading the file facing "A value of type 'Future<List?>' can't be assigned to a variable of type 'List?'." What am i missing?
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class ContractControl extends StatefulWidget {
const ContractControl({super.key});
#override
State<ContractControl> createState() => _ContractControlState();
}
class _ContractControlState extends State<ContractControl> {
//static const List<String> listItems = <String>['Apple', 'Banana'];
Future<List<String>?> getData() async {
try {
String fileData = await rootBundle.loadString('assets/instruments.txt');
List<String> lines = fileData.split('\n');
return lines;
} catch (e) {
throw (e.toString());
}
}
#override
Widget build(BuildContext context) {
List<String>? listItems = getData(); **--> here**
return Scaffold(
appBar: AppBar(title: const Text('Contract Control')),
body: Autocomplete<String>(
optionsBuilder: (TextEditingValue textEditingValue) {
Future<List<String>?> listItems = getData();
if (textEditingValue.text == '') {
return const Iterable<String>.empty();
}
return listItems.where((String item) {
return item.contains(textEditingValue.text.toUpperCase());
});
},
onSelected: (String item) {
print('Item selected');
},
),
);
}
}

Answer 1

getData() is async method. It is Future method, meaning it takes some time to execute. It should be like that: List<String>? listItems = await getData(); But it shows error because you are in build method which is not async. The best solution here is FutureBuilder widget!