Safe Calls and the Not-Null Assertion

Safe calls

The simplest way to call a method or a property on a nullable value is with a safe call, which is a question mark and a dot (?.) instead of just a regular dot (.).

Safe calls work as follows:

• If a value is null, it does nothing and returns null.

• If a value is not null, it works like a regular call.

Points to remember:

• The result of a safe call is always a nullable type because a safe call returns null when it is called on a null. This means that nullability propagates.

• If we need to find out the length of a user’s name, calling user?.name.length will not compile. Even though name is not nullable, the result of user?.name is String?, so we need to use a safe call again: user?.name?.length.