com.google.common.base

Class Suppliers

java.lang.Object

com.google.common.base.Suppliers

@GwtCompatible
public final class Suppliers
extends Object

Useful suppliers.

All methods return serializable suppliers as long as they're given serializable parameters.

Since:

2.0 (imported from Google Collections Library)

Author:

Laurence Gonsalves, Harry Heymann

Method Summary

Methods

Modifier and Type	Method and Description
static Supplier	compose(Function function, Supplier supplier) Returns a new supplier which is the composition of the provided function and supplier.
static Supplier	memoize(Supplier delegate) Returns a supplier which caches the instance retrieved during the first call to get() and returns that value on subsequent calls to get().
static Supplier	memoizeWithExpiration(Supplier delegate, long duration, TimeUnit unit) Returns a supplier that caches the instance supplied by the delegate and removes the cached value after the specified time has passed.
static Supplier	ofInstance(T instance) Returns a supplier that always supplies instance.
static Function<Supplier,T>	supplierFunction() Returns a function that accepts a supplier and returns the result of invoking Supplier.get() on that supplier.
static Supplier	synchronizedSupplier(Supplier delegate) Returns a supplier whose get() method synchronizes on delegate before calling it, making it thread-safe.

Methods inherited from class java.lang.Object

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

Method Detail

compose

public static  Supplier compose(Function function,
                        Supplier supplier)

Returns a new supplier which is the composition of the provided function and supplier. In other words, the new supplier's value will be computed by retrieving the value from supplier, and then applying function to that value. Note that the resulting supplier will not call supplier or invoke function until it is called.

memoize

public static  Supplier memoize(Supplier delegate)

Returns a supplier which caches the instance retrieved during the first call to get() and returns that value on subsequent calls to get(). See: memoization

The returned supplier is thread-safe. The supplier's serialized form does not contain the cached value, which will be recalculated when get() is called on the reserialized instance.

If delegate is an instance created by an earlier call to memoize, it is returned directly.

memoizeWithExpiration

public static  Supplier memoizeWithExpiration(Supplier delegate,
                                    long duration,
                                    TimeUnit unit)

Returns a supplier that caches the instance supplied by the delegate and removes the cached value after the specified time has passed. Subsequent calls to get() return the cached value if the expiration time has not passed. After the expiration time, a new value is retrieved, cached, and returned. See: memoization

The returned supplier is thread-safe. The supplier's serialized form does not contain the cached value, which will be recalculated when get() is called on the reserialized instance.

Parameters:

duration - the length of time after a value is created that it should stop being returned by subsequent get() calls

unit - the unit that duration is expressed in

Throws:

IllegalArgumentException - if duration is not positive

Since:

2.0

ofInstance

public static  Supplier ofInstance(@Nullable
                         T instance)

Returns a supplier that always supplies instance.

synchronizedSupplier

public static  Supplier synchronizedSupplier(Supplier delegate)

Returns a supplier whose get() method synchronizes on delegate before calling it, making it thread-safe.

supplierFunction

@Beta
public static  Function<Supplier,T> supplierFunction()

Returns a function that accepts a supplier and returns the result of invoking Supplier.get() on that supplier.

Since:

8.0