How to write async getter with Flutter/Dart?

Question

I am creating an application in Flutter. In this application, I need to call a library written in Java. Now, the library, written in Java, has a getter and a setter for a property. I want to call these getters and setters from Flutter/Dart, and we want to use it.

static const MethodChannel _channel = const MethodChannel('com.example.java-library');

static Future<String> get versionCode async {
  final String versionCode = await _channel.invokeMethod('getVersionCode');
  return versionCode;
}

static set versionCode(final String code) {
  _channel.invokeMethod('setVersionCode', code);
}

However, if I write code like the above, I will get a warning at runtime.

The return type of getter 'versionCode' is 'Future<String>' which isn't assignable to the type 'String' of its setter 'versionCode'.
Try changing the types so that they are compatible.

How can I avoid the problem so that the warning does not appear?

I faced the same issue, do you have a solution?, this happens when im update dart sdk — Alejandro Viquez
– Alejandro Viquez, Commented May 1, 2021 at 21:31

Ahmed Erabti · Accepted Answer · 2020-07-01 06:17:34Z

1

Would be better to use methods like so:

static Future<String> getVersionCode() async {
  final String versionCode = await _channel.invokeMethod('getVersionCode');
  return versionCode;
}

static void setVersionCode(String code){
  _channel.invokeMethod('setVersionCode', code);
}

When you want to retrieve(use) the value:

Future<void> anyOtherPlace()async{
   final String value = await getVersionCode();
}

edited Jul 1, 2020 at 6:17

answered Jul 1, 2020 at 6:14

Ahmed Erabti

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1 Comment

Ahmed Erabti Over a year ago

You have to await for it, invokeMethod is async so you must await it.

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