org.apache.reef.util

Class Optional<T>

java.lang.Object

org.apache.reef.util.Optional<T>

All Implemented Interfaces:

Serializable

@Immutable
 @ThreadSafe
public final class Optional<T>
extends Object
implements Serializable

Represents an optional value. Loosely based on The Java 8 version, but filtered for Java 7 compatibility.

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
static <T> Optional<T>	empty()
boolean	equals(Object obj)
T	get()
int	hashCode()
boolean	isPresent()
static <T> Optional<T>	of(T value)
static <T> Optional<T>	ofNullable(T value)
T	orElse(T other)
String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

of

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

Returns:

An Optional with the given value.

Throws:

IllegalArgumentException - if the value is null

empty

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

Returns:

an Optional with no value.

ofNullable

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

Returns:

An optional representing the given value, or an empty Optional.

get

public T get()

Returns:

the value represented or null, if isPresent() is false.

orElse

public T orElse(T other)

Parameters:

other -

Returns:

the value of this Optional or other, if no value exists.

isPresent

public boolean isPresent()

Returns:

true if there is a value, false otherwise.

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object