Cookbooks
Dart
Chapter 3. Numbers
Generating random numbers

Dart:
Generating random numbers

How to:

Dart’s core library includes support for generating random numbers with the Random class found in dart:math. Here’s a basic example:

import 'dart:math';

void main() {
  var rand = Random();
  int randomNumber = rand.nextInt(100); // Generates a random integer between 0 and 99
  double randomDouble = rand.nextDouble(); // Generates a random double between 0.0 and 1.0
  print(randomNumber);
  print(randomDouble);
}

Sample output: (This will vary each time it is run)

23
0.6722390975465775

For use cases requiring cryptographic randomness, Dart offers the Random.secure constructor:

import 'dart:math';

void main() {
  var secureRand = Random.secure();
  int secureRandomNumber = secureRand.nextInt(100);
  print(secureRandomNumber);
}

Sample output: (This will vary each time it is run)

45

If you’re working on Flutter projects or need more complex randomness, you might find the faker package useful for generating a wide range of random data, such as names, addresses, and dates.

To use faker, first, add it to your pubspec.yaml file:

dependencies:
  faker: ^2.0.0

Then, import and use it as shown:

import 'package:faker/faker.dart';

void main() {
  final faker = Faker();
  print(faker.person.name()); // Generates a random name
  print(faker.address.city()); // Generates a random city name
}

Sample output:

Josie Runolfsdottir
East Lysanne
Rounding numbers