Double question mark Python

Null-aware operators are used in almost every programming language to check whether the given variable value is Null . The keyword for Null in the programming language Dart is null. Null means a variable which has no values assign ever and the variable is initialized with nothing like.

Answer (1) A nullable type by adding a question mark (?) after the type name. For example, a variable _contacts? can contain a value, or it can be null. Answer (2) It is called “Null-aware operators”.

This is with null safety, the question mark means that this String? can possibly be null and flutter will allow you to assign null to it . String can never be null and you’ll get an error before compiling.29 Mar 2021