Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

Optional

A box that holds one value or is empty, returned when a result may be missing.

java.util.Optional, a container of zero or one non-null value, returned by findFirst, max, min and one-argument reduce; meant for return types, not fields or parameters.

Examples

findEmail(user).orElse("(none)")