insert method Null safety
- int index,
- E element
element at position
index in this list.
This increases the length of the list by one and shifts all objects at or after the index towards the end of the list.
The list must be growable.
index value must be non-negative and no greater than length.
final numbers = <int>[1, 2, 3, 4]; const index = 2; numbers.insert(index, 10); print(numbers); // [1, 2, 10, 3, 4]
void insert(int index, E element);