Flutter multiple async methods for parrallel execution

Waiting on multiple Futures to complete using Future.wait()
If the order of execution of the functions is not important, you can use Future.wait().

The functions get triggered in quick succession; when all of them complete with a value, Future.wait() returns a new Future. This Future completes with a list containing the values produced by each function.

Future
    .wait([firstAsync(), secondAsync(), thirdAsyncC()])
    .then((List responses) => chooseBestResponse(responses))
    .catchError((e) => handleError(e));

or with async/await

try {
    List responses = await Future.wait([firstAsync(), secondAsync(), thirdAsyncC()]);
} catch (e) {
    handleError(e)
}

If any of the invoked functions completes with an error, the Future returned by Future.wait() also completes with an error. Use catchError() to handle the error.

Resource:https://v1-dartlang-org.firebaseapp.com/tutorials/language/futures#waiting-on-multiple-futures-to-complete-using-futurewait