What is the purpose of the Maybe operator in the RxJava library and in what cases is it used?

In RxJava, the Maybe operator represents a type of Observable that can complete in one of three ways:

• Emit a single value and complete successfully.
• Complete without a value (empty).
• Complete with an error.

Maybe is used when the result can be either a single element or none at all, for example, when querying a database where a record may be found or not.

Example of usage:

Maybe<String> maybeUser = getUserFromDb(userId);

maybeUser.subscribe(
    user -> System.out.println("User found: " + user),
    throwable -> System.err.println("Error: " + throwable),
    () -> System.out.println("User not found")
);

Here, getUserFromDb returns a Maybe<String>, which either emits a user or completes without a value if the user is not found.