[dart:async] Future Chain

main.dart

import 'dart:core';
import 'dart:async';

Future<bool> exception = Future<bool>.delayed(Duration(seconds: 1), () {
  print('Somehow, a exception happend...');
  
  throw 'Just a Exception, freeze!';
});

Future procedure = Future(() {
  return exception
    .then((val) {
      print('Nonsense');
    })
    .catchError((err) {
      print('Exception happend, rethrow it');
      throw err;
    });
});

main() {
  procedure
    .then((val) {
      print('Succeed, $val');
    })
    .catchError((err) {
      print('A Exception captured, try to recovering...');

      return Future.value(1024);
    })
    .then((val) {
      print('Recovered from exception, val is $val');
    });
}