Package org.apache.wayang.core.util

Class Optional<T>

java.lang.Object

org.apache.wayang.core.util.Optional<T>

public abstract class Optional<T>
extends Object

Utility similar to Optional. However, it supports null as a valid value.

Constructor Summary

Constructors

Constructor	Description
Optional()

Method Summary

Modifier and Type	Method	Description
abstract T	getValue()
abstract boolean	isAvailable()
static <T> Optional<T>	na()	Create a n/a instance.
static <T> Optional<T>	of(T value)	Create a new instance with the given value.
abstract Stream<T>	stream()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Optional

public Optional()

Method Details

isAvailable

public abstract boolean isAvailable()

Returns:

whether this instance contains a value.

getValue

public abstract T getValue()

Returns:

the value contained by this instance

Throws:

IllegalStateException - if isAvailable() is false

stream

public abstract Stream<T> stream()

Returns:

a Stream containing the optional value

na

public static <T> Optional<T> na()

Create a n/a instance.

Returns:

an Optional without a value

of

public static <T> Optional<T> of(T value)

Create a new instance with the given value.

Parameters:

value - the value of the new Optional

Returns:

the new instance