org.springframework.data.util

Class Lazy<T>

java.lang.Object

org.springframework.data.util.Lazy<T>

All Implemented Interfaces:

Supplier<T>

public class Lazy<T>
extends Object
implements Supplier<T>

Simple value type to delay the creation of an object using a Supplier returning the produced object for subsequent lookups. Note, that no concurrency control is applied during the lookup of get(), which means in concurrent access scenarios, the provided Supplier can be called multiple times.

Since:

2.0

Author:

Oliver Gierke, Mark Paluch, Henning Rohlfs

Constructor Summary

Constructors

Constructor and Description
Lazy(Supplier<? extends T> supplier) Deprecated. prefer of(Supplier), to be turned private in 2.5.

Method Summary

Modifier and Type	Method and Description
static <T> Lazy<T>	empty() Creates a pre-resolved empty Lazy.
boolean	equals(Object o)
<S> Lazy<S>	flatMap(Function<? super T,Lazy<? extends S>> function) Creates a new Lazy with the given Function lazily applied to the current one.
T	get() Returns the value created by the configured Supplier.
T	getNullable() Returns the value of the lazy evaluation.
Optional<T>	getOptional() Returns the Optional value created by the configured Supplier, allowing the absence of values in contrast to get().
int	hashCode()
<S> Lazy<S>	map(Function<? super T,? extends S> function) Creates a new Lazy with the given Function lazily applied to the current one.
static <T> Lazy<T>	of(Supplier<? extends T> supplier) Creates a new Lazy to produce an object lazily.
static <T> Lazy<T>	of(T value) Creates a new Lazy to return the given value.
Lazy<T>	or(Supplier<? extends T> supplier) Returns a new Lazy that will consume the given supplier in case the current one does not yield in a result.
Lazy<T>	or(T value) Returns a new Lazy that will return the given value in case the current one does not yield in a result.
T	orElse(T value) Returns the value of the lazy computation or the given default value in case the computation yields null.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lazy

@Deprecated
public Lazy(Supplier<? extends T> supplier)

Deprecated. prefer of(Supplier), to be turned private in 2.5.

Creates a new Lazy instance for the given supplier.

Parameters:

supplier -

Method Detail

of

public static <T> Lazy<T> of(Supplier<? extends T> supplier)

Creates a new Lazy to produce an object lazily.

Type Parameters:

T - the type of which to produce an object of eventually.

Parameters:

supplier - the Supplier to create the object lazily.

Returns:

of

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

Creates a new Lazy to return the given value.

Type Parameters:

T - the type of the value to return eventually.

Parameters:

value - the value to return.

Returns:

empty

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

Creates a pre-resolved empty Lazy.

Returns:

Since:

2.1

get

public T get()

Returns the value created by the configured Supplier. Will return the calculated instance for subsequent lookups.

Specified by:

get in interface Supplier<T>

Returns:

getOptional

public Optional<T> getOptional()

Returns the Optional value created by the configured Supplier, allowing the absence of values in contrast to get(). Will return the calculated instance for subsequent lookups.

Returns:

or

public Lazy<T> or(Supplier<? extends T> supplier)

Returns a new Lazy that will consume the given supplier in case the current one does not yield in a result.

Parameters:

supplier - must not be null.

Returns:

or

public Lazy<T> or(T value)

Returns a new Lazy that will return the given value in case the current one does not yield in a result.

Parameters:

supplier - must not be null.

Returns:

orElse

@Nullable
public T orElse(@Nullable
                          T value)

Returns the value of the lazy computation or the given default value in case the computation yields null.

Parameters:

value -

Returns:

map

public <S> Lazy<S> map(Function<? super T,? extends S> function)

Creates a new Lazy with the given Function lazily applied to the current one.

Parameters:

function - must not be null.

Returns:

flatMap

public <S> Lazy<S> flatMap(Function<? super T,Lazy<? extends S>> function)

Creates a new Lazy with the given Function lazily applied to the current one.

Parameters:

function - must not be null.

Returns:

getNullable

@Nullable
public T getNullable()

Returns the value of the lazy evaluation.

Returns:

Since:

2.2

equals

public boolean equals(@Nullable
                      Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object