void replaceRange(int start, int end, Iterable<E> replacement)

Removes the objects in the range start inclusive to end exclusive and inserts the contents of replacement in its place.

List<int> list = [1, 2, 3, 4, 5];
list.replaceRange(1, 4, [6, 7]);
list.join(', '); // '1, 6, 7, 5'

An error occurs if start..end is not a valid range for this.

This method does not work on fixed-length lists, even when replacement has the same number of elements as the replaced range. In that case use setRange instead.

Source

void replaceRange(int start, int end, Iterable<E> replacement);