Nullability

NULL (class)

null (singleton object)

int // cannot contain null
int? // includes null

// note nullable types still contain the same methods as their non nullable 
// brothers. But you may need to check to ensure that the variable is not null

dynamic // includes null even without a ?

All ? types are init as null

Null operators

• ??: If-null operator.
  text = message ?? 'Error';
  if left is null use right
  

• ??=: Null-aware assignment operator.
  fontSize ??= 20.0;
if left is null, left = right
  

• ?.: Null-aware access operator. && Null-aware method invocation operator.
  print(age?.isNegative);
  if age is null, return null
  Note: isNeg will not work if null normally
  

• !: Null assertion operator.
  String nonNullableString = myNullableString!;
  Allows you to turn a nullable value into non nullable
  Note: wont work if it is null
  

• ?..: Null-aware cascade operator.

user
  ?..name = 'Ray'
  ..id = 42;

// if user is null then abort

• ?[]: Null-aware index operator.

• ...?: Null-aware spread operator.

Null operators

• ??: If-null operator.

• ??=: Null-aware assignment operator.

• ?.: Null-aware access operator.

• ?.: Null-aware method invocation operator.

• !: Null assertion operator.

• ?..: Null-aware cascade operator.

• ?[]: Null-aware index operator.

• ...?: Null-aware spread operator.