Tutorial by Examples

Future<Results> costlyQuery() { var completer = new Completer(); database.query("SELECT * FROM giant_table", (results) { // when complete completer.complete(results); }, (error) { completer.completeException(error); }); // this returns essentially im...

import 'dart:async'; Future main() async { var value = await _waitForValue(); print("Here is the value: $value"); //since _waitForValue() returns immediately if you un it without await you won't get the result var errorValue = "not finished yet"; _waitForValue()...

Dart has a robust async library, with Future, Stream, and more. However, sometimes you might run into an asynchronous API that uses callbacks instead of Futures. To bridge the gap between callbacks and Futures, Dart offers the Completer class. You can use a Completer to convert a callback into a Fut...