javautilOptional

java.util.Optional is a container object in the Java standard library that may or may not contain a non-null value. Introduced in Java 8, it is designed to express the presence or absence of a value explicitly, helping to reduce null-related errors and encourage deliberate handling of missing data. Optional is not a collection; it is a wrapper around a value that may be empty.

Key features and API basics include the static factories Optional.empty() and Optional.ofNullable(T value) (and Optional.of(T value) which requires a non-null value). It provides methods such as isPresent() and ifPresent(Consumer) to test or act when a value exists, and get() to retrieve the value (which throws if empty). It also supports defaulting and exception signaling via orElse(T other), orElseGet(Supplier<? extends T>), and orElseThrow(Supplier<? extends Throwable>). Transformation and composition are available through map(Function<? super T, ? extends U>) and flatMap(Function<? super T, Optional<? extends U>>). Optional can be converted to a stream with stream() for use in streams.

Common usage patterns include wrapping potentially null results with Optional.ofNullable, supplying defaults with orElse or orElseGet, throwing exceptions with orElseThrow, and chaining transformations with map/flatMap. Best practices advise against overusing Optional for fields or method parameters and against calling get() without checking presence. Use orElseGet for expensive defaults and prefer map/flatMap to avoid nested Optionals.

Example:

Optional<String> nameOpt = Optional.ofNullable(name);

String display = nameOpt.orElse("Unknown");