com.google.common.base
Class Suppliers

java.lang.Object
  com.google.common.base.Suppliers

public final class Suppliers
extends java.lang.Object

Useful suppliers.

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

Author:

Laurence Gonsalves, Harry Heymann

Nested Class Summary

static class

Suppliers.CyclicDependencyException Exception thrown when a memoizing supplier tries to get its own value.

Method Summary

static <F,T> Supplier<T>	compose(Function<? super F,T> function, Supplier<F> first) Returns a new supplier which is the composition of the provided function and supplier.
static <T> Supplier<T>	memoize(Supplier<T> 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 <T> Supplier<T>	ofInstance(T instance) Returns a supplier that always supplies instance.
static <T> Supplier<T>	synchronizedSupplier(Supplier<T> 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 <F,T> Supplier<T> compose(Function<? super F,T> function,
                                        Supplier<F> first)

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 first, and then applying function to that value. Note that the resulting supplier will not call first or invoke function until it is called.

memoize

public static <T> Supplier<T> memoize(Supplier<T> 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 will throw CyclicDependencyException if the call to Supplier.get() tries to get its own value. The returned supplier is not thread-safe.

ofInstance

public static <T> Supplier<T> ofInstance(@Nullable
                                         T instance)

Returns a supplier that always supplies instance.

synchronizedSupplier

public static <T> Supplier<T> synchronizedSupplier(Supplier<T> delegate)

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