lastIndexWhere method

  1. @override
int lastIndexWhere(
  1. bool test(
    1. E element
    ), [
  2. int? start
])
override

The last index in the list that satisfies the provided test.

Searches the list from index start to 0. The first time an object o is encountered so that test(o) is true, the index of o is returned. If start is omitted, it defaults to the length of the list.

final notes = <String>['do', 're', 'mi', 're'];
final first = notes.lastIndexWhere((note) => note.startsWith('r')); // 3
final second = notes.lastIndexWhere((note) => note.startsWith('r'),
    2); // 1

Returns -1 if element is not found.

final notes = <String>['do', 're', 'mi', 're'];
final index = notes.lastIndexWhere((note) => note.startsWith('k'));
print(index); // -1

Implementation

@override
int lastIndexWhere(bool Function(E element) test, [int? start]) {
  if (!test(value)) {
    return -1;
  }
  // test(value) must be true.
  if (start == null) {
    return length - 1;
  }
  if (start < 0 || start > length) {
    return length - 1;
  } else {
    return start;
  }
}