singleWhere method Null safety
- bool test(
- E element
- {E orElse(
override
Returns the single element that satisfies test
.
Checks elements to see if test(element)
returns true.
If exactly one element satisfies test
, that element is returned.
If more than one matching element is found, throws StateError.
If no matching element is found, returns the result of orElse
.
If orElse
is omitted, it defaults to throwing a StateError.
Implementation
E singleWhere(bool test(E element), {E Function()? orElse}) {
int length = this.length;
late E match;
bool matchFound = false;
for (int i = 0; i < length; i++) {
E element = this[i];
if (test(element)) {
if (matchFound) {
throw IterableElementError.tooMany();
}
matchFound = true;
match = element;
}
if (length != this.length) {
throw ConcurrentModificationError(this);
}
}
if (matchFound) return match;
if (orElse != null) return orElse();
throw IterableElementError.noElement();
}