lastWhere method

  1. @override
E lastWhere(
  1. bool test(
    1. E element
    ), {
  2. E orElse()?,
})
override

The last element that satisfies the given predicate test.

An iterable that can access its elements directly may check its elements in any order (for example a list starts by checking the last element and then moves towards the start of the list). The default implementation iterates elements in iteration order, checks test(element) for each, and finally returns that last one that matched.

Example:

final numbers = <int>[1, 2, 3, 5, 6, 7];
var result = numbers.lastWhere((element) => element < 5); // 3
result = numbers.lastWhere((element) => element > 5); // 7
result = numbers.lastWhere((element) => element > 10,
    orElse: () => -1); // -1

If no element satisfies test, the result of invoking the orElse function is returned. If orElse is omitted, it defaults to throwing a StateError.

Implementation

@override
E lastWhere(bool Function(E element) test, {E Function()? orElse}) {
  for (var i = length - 1; i >= 0; i--) {
    final element = elementAt(i);
    if (test(element)) {
      return element;
    }
  }
  if (orElse != null) {
    return orElse();
  }
  throw _noElements();
}