Dart Future.value()
Syntax & Examples

Future.value constructor

The `Future.value` constructor in Dart creates a future that is completed with a specified value.

Syntax of Future.value

The syntax of Future.Future.value constructor is:

Future.value([FutureOr<T> value ])

This Future.value constructor of Future creates a future completed with value.

Parameters

ParameterOptional/RequiredDescription
valueoptionalThe value with which the future should be completed. Defaults to null if not provided.

✐ Examples

1 Completion of a future with an integer value

In this example,

  1. We create a future using `Future.value` with an integer value of 42.
  2. We use `then` to handle the completion of the future and print the completed value.

Dart Program

void main() {
  Future<int> future = Future.value(42);
  future.then((value) {
    print('Future completed with value: $value');
  });
}

Output

Future completed with value: 42

2 Completion of a future with a string value

In this example,

  1. We create a string variable `message`.
  2. We create a future using `Future.value` with the string message.
  3. We use `then` to handle the completion of the future and print the completed value.

Dart Program

void main() {
  String message = 'Hello, Dart!';
  Future<String> future = Future.value(message);
  future.then((value) {
    print(value);
  });
}

Output

Hello, Dart!

3 Completion of a future with a list

In this example,

  1. We create a list of integers `numbers`.
  2. We create a future using `Future.value` with the list.
  3. We use `then` to handle the completion of the future and print the completed list.

Dart Program

void main() {
  List<int> numbers = [1, 2, 3, 4, 5];
  Future<List<int>> future = Future.value(numbers);
  future.then((value) {
    print(value);
  });
}

Output

[1, 2, 3, 4, 5]

Summary

In this Dart tutorial, we learned about Future.value constructor of Future: the syntax and few working examples with output and detailed explanation for each example.