Future.value constructor - Future - dart:async library (original) (raw)

Future<T>.value([

1. FutureOr<T>? value ])

Creates a future completed with value.

If value is a future, the created future waits for thevalue future to complete, and then completes with the same result. Since a value future can complete with an error, so can the future created by Future.value, even if the name suggests otherwise.

If value is not a Future, the created future is completed with the value value, equivalently to new Future<T>.sync(() => value).

If value is omitted or null, it is converted to FutureOr<T> byvalue as FutureOr<T>. If T is not nullable, then a non-null valuemust be provided, otherwise the construction throws.

Use Completer to create a future now and complete it later.

Example:

Future<int> getFuture() {
 return Future<int>.value(2021);
}

final result = await getFuture();

Implementation

@pragma("vm:entry-point")
@pragma("vm:prefer-inline")
factory Future.value([FutureOr<T>? value]) {
  return new _Future<T>.immediate(value == null ? value as T : value);
}