ifPresent method
void
ifPresent([
- void action(
- T
If a value is present, performs the given action with the value, otherwise does nothing.
action
the action to be performed, if a value is present
Throws InvalidArgumentException if value is present and the given action is null.
Example
Optional<String> name = Optional.of("Eve");
Optional<String> empty = Optional.empty();
name.ifPresent((value) => print("Hello, $value!")); // Hello, Eve!
empty.ifPresent((value) => print("This won't print"));
// Useful for side effects
Optional<List<String>> items = Optional.of(["a", "b", "c"]);
items.ifPresent((list) => list.add("d"));
Implementation
void ifPresent([void Function(T)? action]) {
if (action == null) {
throw InvalidArgumentException('action cannot be null');
}
if (_value != null) {
action(_value as T);
}
}