1. ?. operator

null checking

                User user = new User.fromResponse(response);
                // null check
                if (user != null) {
                  this.userAge = user.age;
                }

              

Shorter null checking

              User user = new User.fromResponse(response);

              // delightfully shorter null check
              this.userAge = user?.age; 

              

2. The ?? operator

you can use the double question mark (??) to assign a "fallback" or default value.

              User user = new User.fromResponse(response);
  
              // If user.age is null, defaults to 18
              this.userAge = user.age ?? 18;  <1>
              // etc.

              

3. The ??= operator

              int x = 5
              x ??= 3;
              

In the second line, x will not be assigned 3, because it already has a value.