Null class Null safety

The reserved word null denotes an object that is the sole instance of this class.

The Null class is the only class which does not implement Object. It is a compile-time error for a class to attempt to extend or implement Null.

The language contains a number of specialized operators for working with null value. Examples:

e1!       // Throws if e1 is null.
e2 ?? e3  // Same as e2, unless e2 is null, then use value of e3
x ??= e4  // Same as x unless x is null, then same as `x = e4`.
e5?.foo() // call `foo` on e5, unless e5 is null.
[...? e6] // spreads e6 into the list literal, unless e6 is null.