compact1, compact2, compact3

java.util

Class Optional<T>

java.lang.Object

java.util.Optional<T>

public final class Optional<T>
extends Object

A container object which may or may not contain a non-null value. If a value is present, isPresent() will return true and get() will return the value.

Additional methods that depend on the presence or absence of a contained value are provided, such as orElse() (return a default value if value not present) and ifPresent() (execute a block of code if the value is present).

This is a value-based class; use of identity-sensitive operations (including reference equality (==), identity hash code, or synchronization) on instances of Optional may have unpredictable results and should be avoided.

Since:

1.8

Method Summary

Modifier and Type	Method	Description
static <T> Optional<T>	empty()	Returns an empty Optional instance.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this Optional.
Optional<T>	filter(Predicate<? super T> predicate)	If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.
<U> Optional<U>	flatMap(Function<? super T,Optional<U>> mapper)	If a value is present, apply the provided Optional-bearing mapping function to it, return that result, otherwise return an empty Optional.
T	get()	If a value is present in this Optional, returns the value, otherwise throws NoSuchElementException.
int	hashCode()	Returns the hash code value of the present value, if any, or 0 (zero) if no value is present.
void	ifPresent(Consumer<? super T> consumer)	If a value is present, invoke the specified consumer with the value, otherwise do nothing.
boolean	isPresent()	Return true if there is a value present, otherwise false.
<U> Optional<U>