Null Safety Instructions in Dart

null-safety-dart.md

Null Safety Instruction

• In dart unassigned variables are by default assigned null at initialization.
• In Null safety a variable with a static type should be assigned some value at initialization or if that variable is to be assigned a value later then should be declare with late or made null aware by using ? operator after its type.
• Statically typed variables declared without null aware (?) operator can never be null in Null safety
• @required is changed to required in Null Safety
• We have various operators and annotations in Null Safety such as ?. ?? ??= !. late required

?? this is Null-ish Coalescing operator which assigns a LHS value only if it's not null otherwise it assigns RHS value

• Eg. a = b ?? c

?. this is null aware access operator which basically tells that value being accessed can be null

• Eg. someString?.toLowerCas() // will output null if someString is null otherwise gives the result

! Bang operator is to be used if you are sure that the value being accessed is not null

• Eg. object!["property"]

A good read about null operators in dart

Official guide