MapgetOrDefaultkey

MapgetOrDefaultkey is a descriptive name sometimes used to refer to the "get-or-default" operation on map-like containers: retrieving the value associated with a given key, or returning a supplied default when the key is not present. The pattern appears across many programming languages and libraries; for example, Java's Map.getOrDefault(key, defaultValue) and Python's dict.get(key, default) implement this behavior.

Typical semantics are non-mutating: the map is not modified when a default is returned. This distinguishes get-or-default from lookup-plus-insert operations such as Java's computeIfAbsent, which may create and store a new value when a key is missing. The operation simplifies code by avoiding explicit presence checks and conditional assignments.

Common use cases include providing fallback values, handling optional configuration entries, and simplifying aggregation logic. Important considerations include thread-safety (maps that are not concurrent can still require external synchronization), the handling of null keys or values in specific implementations, and the risk of returning mutable default objects that are inadvertently shared. Differences between languages and libraries—such as whether the method accepts a supplier for lazily computed defaults—should be consulted in the relevant API documentation.