elementAtAsOptional method
Returns the index
th element wrapped by an Optional
if this element
exists, otherwise returns Optional.empty
.
If the index passed is invalid, Optional.empty
is returned as well.
Index zero represents the first element (so elementAt(0)
is equivalent
to first
).
This lookup can not distinguish between handling and invalid index
and
containing the value null
at the requested index.
Methods like contains or length can be used if the distinction is
important.
Implementation
Optional<T> elementAtAsOptional(int index) =>
getValueIf(_isValidIndex(index), () => _list.elementAt(index));