length property Null safety
The number of objects in this list.
The valid indices for a list are 0 through length - 1.
Implementation
int get length;Changes the length of this list.
If newLength is greater than
the current length, entries are initialized to null.
Increasing the length fails if the element type does not allow null.
Throws an UnsupportedError if the list is fixed-length or
if attempting to enlarge the list when null is not a valid element.
Implementation
set length(int newLength);