io.lettuce.core

Class Value<V>

java.lang.Object

io.lettuce.core.Value<V>

Type Parameters:

V - Value type.

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

GeoValue, KeyValue, ScoredValue

public class Value<V>
extends Object
implements Serializable

A value 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 getValueOrElse() (return a default value if value not present).

Author:

Mark Paluch

See Also:

Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Value() Serializable constructor.
protected	Value(V value)

Method Summary

Modifier and Type	Method and Description
static <V> Value<V>	empty() Returns an empty Value instance.
boolean	equals(Object o)
static <T extends V,V> Value<V>	from(Optional<T> optional) Creates a Value from an Optional.
static <T extends V,V> Value<V>	fromNullable(T value) Creates a Value from a value.
V	getValue() If a value is present in this Value, returns the value, otherwise throws NoSuchElementException.
V	getValueOrElse(V other) Return the value if present, otherwise return other.
V	getValueOrElseGet(Supplier<V> otherSupplier) Return the value if present, otherwise invoke other and return the result of that invocation.
<X extends Throwable> V	getValueOrElseThrow(Supplier<? extends X> exceptionSupplier) Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.
int	hashCode()
boolean	hasValue() Return true if there is a value present, otherwise false.
void	ifEmpty(Runnable runnable) If no value is present, invoke the specified Runnable, otherwise do nothing.
void	ifHasValue(Consumer<? super V> consumer) If a value is present, invoke the specified Consumer with the value, otherwise do nothing.
void	ifHasValueOrElse(Consumer<? super V> consumer, Runnable emptyAction) If a value is present, invoke the specified Consumer with the value, otherwise call emptyAction.
boolean	isEmpty() Return true if there is no value present, otherwise false.
static <T extends V,V> Value<V>	just(T value) Creates a Value from a value.
<R> Value<R>	map(Function<? super V,? extends R> mapper) Returns a Value consisting of the results of applying the given function to the value of this element.
Optional<V>	optional() Returns an Optional wrapper for the value.
Stream<V>	stream() Returns a Stream wrapper for the value.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Value

protected Value()

Serializable constructor.

Value

protected Value(V value)

Parameters:

value - the value, may be null.

Method Detail

from

public static <T extends V,V> Value<V> from(Optional<T> optional)

Creates a Value from an Optional. The resulting value contains the value from the Optional if a value is present. Value is empty if the Optional is empty.

Parameters:

optional - the optional. May be empty but never null.

Returns:

the Value.

fromNullable

public static <T extends V,V> Value<V> fromNullable(T value)

Creates a Value from a value. The resulting value contains the value if the value is not null.

Parameters:

value - the value. May be null.

Returns:

the Value.

empty

public static <V> Value<V> empty()

Returns an empty Value instance. No value is present for this instance.

Returns:

the Value.

just

public static <T extends V,V> Value<V> just(T value)

Creates a Value from a value. The resulting value contains the value.

Parameters:

value - the value. Must not be null.

Returns:

the Value.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

getValue

public V getValue()

If a value is present in this Value, returns the value, otherwise throws NoSuchElementException.

Returns:

the non-null value held by this Optional.

Throws:

NoSuchElementException - if there is no value present.

See Also:

hasValue()

hasValue

public boolean hasValue()

Return true if there is a value present, otherwise false.

Returns:

true if there is a value present, otherwise false.

isEmpty

public boolean isEmpty()

Return true if there is no value present, otherwise false.

Returns:

true if there is no value present, otherwise false.

Since:

6.1

getValueOrElseGet

public V getValueOrElseGet(Supplier<V> otherSupplier)

Return the value if present, otherwise invoke other and return the result of that invocation.

Parameters:

otherSupplier - a Supplier whose result is returned if no value is present. Must not be null.

Returns:

the value if present otherwise the result of other.get().

Throws:

NullPointerException - if value is not present and other is null.

getValueOrElse

public V getValueOrElse(V other)

Return the value if present, otherwise return other.

Parameters:

other - the value to be returned if there is no value present, may be null.

Returns:

the value, if present, otherwise other.

getValueOrElseThrow

public <X extends Throwable> V getValueOrElseThrow(Supplier<? extends X> exceptionSupplier)
                                            throws X extends Throwable

Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.

Type Parameters:

X - Type of the exception to be thrown

Parameters:

exceptionSupplier - The supplier which will return the exception to be thrown, must not be null.

Returns:

the present value

Throws:

X - if there is no value present

X extends Throwable

map

public <R> Value<R> map(Function<? super V,? extends R> mapper)

Returns a Value consisting of the results of applying the given function to the value of this element. Mapping is performed only if a value is present.

Type Parameters:

R - The element type of the new value.

Parameters:

mapper - a stateless function to apply to each element.

Returns:

the new Value.

ifHasValue

public void ifHasValue(Consumer<? super V> consumer)

If a value is present, invoke the specified Consumer with the value, otherwise do nothing.

Parameters:

consumer - block to be executed if a value is present, must not be null.

ifHasValueOrElse

public void ifHasValueOrElse(Consumer<? super V> consumer,
                             Runnable emptyAction)

If a value is present, invoke the specified Consumer with the value, otherwise call emptyAction.

Parameters:

consumer - block to be executed if a value is present, must not be null.

emptyAction - block to be executed if a value is absent, must not be null.

Since:

6.1

ifEmpty

public void ifEmpty(Runnable runnable)

If no value is present, invoke the specified Runnable, otherwise do nothing.

Parameters:

runnable - block to be executed if no value value is present, must not be null.

optional

public Optional<V> optional()

Returns an Optional wrapper for the value.

Returns:

Optional wrapper for the value.

stream

public Stream<V> stream()

Returns a Stream wrapper for the value. The resulting stream contains either the value if a this value has a value or it is empty if the value is empty.

Returns:

Stream wrapper for the value.