Waiting async/await function totally - flutter

Question

In the beginning of system ,I need to load the xml file.
I use async/await to wait for rootBundle.loadString finish.
However in this case, print ("I can wait rootBundle here"); is executed after rootBundle.loadString finish, runApp(MyApp()) starts before finished.
Is there a way to execute runApp() after rootBundle.loadString finish
Because my whole setting is written in one xml files. so I want to make sure to load before first building.
void main(){
inter = new Internationalize();
inter.init();
runApp(MyApp());
}
class Internationalize{
var intls = {};
var xmlBody;
void init(){
print("internationalize class start");
rootBundle.loadString('assets/i18n/en/strings.xml').then(
(String contents) {
var document = xml.parse(contents);
xmlBody = document.findAllElements('string');
print("load finish");
});
print ("I can wait rootBundle here");
}
}

Answer 1

void main() async { // mark it async
WidgetsFlutterBinding.ensureInitialized(); // mandatory since Flutter 1.9 if you're making this method async
inter = new Internationalize();
await inter.init(); // await here
runApp(MyApp());
}
class Internationalize {
var intls = {};
var xmlBody;
Future<void> init() async { // make it Future<void>
print("internationalize class start");
String contents = await rootBundle.loadString('assets/i18n/en/strings.xml'); // await on loadString
var document = xml.parse(contents);
xmlBody = document.findAllElements('string');
print("load finish");
print("I can wait rootBundle here");
}
}

Answer 2

This is the same answer as given by #CopsOnRoad with some explanation.
You should separate the use of future response rootBundle.loadString().
try following:
String contents = await rootBundle.loadString('assets/i18n/en/strings.xml');
var document = xml.parse(contents);
xmlBody = document.findAllElements('string');
print("load finish");
Note: you'll need to add async modifier in all methods, even in the main method as well and add await before every method call.
i.e.:
void main(){
...
await inter.init();
...
}
...
Future<void> init async {
String contents = await rootBundle.loadString('assets/i18n/en/strings.xml');
var document = xml.parse(contents);
xmlBody = document.findAllElements('string');
print("load finish");
}