com.google.common.cache
Interface Cache<K,V>

All Superinterfaces:

Function<K,V>

All Known Subinterfaces:

LoadingCache<K,V>

All Known Implementing Classes:

AbstractCache, AbstractLoadingCache, ForwardingCache, ForwardingCache.SimpleForwardingCache, ForwardingLoadingCache, ForwardingLoadingCache.SimpleForwardingLoadingCache

@Beta
@GwtCompatible
public interface Cache<K,V>
extends Function<K,V>

A semi-persistent mapping from keys to values. Cache entries are manually added using #get(K, Callable) or #put(K, V), and are stored in the cache until either evicted or manually invalidated.

Note: in release 12.0, all methods moved from Cache to LoadingCache will be deleted from Cache. As part of this transition Cache will no longer extend Function.

Implementations of this interface are expected to be thread-safe, and can be safely accessed by multiple concurrent threads.

All methods other than getIfPresent(K) are optional.

Since:

10.0

Author:

Charles Fry

Method Summary

V	apply(K key) Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).
ConcurrentMap<K,V>	asMap() Returns a view of the entries stored in this cache as a thread-safe map.
void	cleanUp() Performs any pending maintenance operations needed by the cache.
V	get(K key) Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).
V	get(K key, Callable<? extends V> valueLoader) Returns the value associated with key in this cache, obtaining that value from valueLoader if necessary.
ImmutableMap<K,V>	getAllPresent(Iterable<? extends K> keys) Returns a map of the values associated with keys in this cache.
V	getIfPresent(K key) Returns the value associated with key in this cache, or null if there is no cached value for key.
V	getUnchecked(K key) Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).
void	invalidate(Object key) Discards any cached value for key key.
void	invalidateAll() Discards all entries in the cache.
void	invalidateAll(Iterable<?> keys) Discards any cached values for keys keys.
void	put(K key, V value) Associates value with key in this cache.
long	size() Returns the approximate number of entries in this cache.
CacheStats	stats() Returns a current snapshot of this cache's cumulative statistics.

Methods inherited from interface com.google.common.base.Function

equals

Method Detail

getIfPresent

@Nullable
V getIfPresent(K key)

Returns the value associated with key in this cache, or null if there is no cached value for key.

Since:

11.0

get

V get(K key,
      Callable<? extends V> valueLoader)
      throws ExecutionException

Returns the value associated with key in this cache, obtaining that value from valueLoader if necessary. No observable state associated with this cache is modified until loading completes. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern.

Warning: as with CacheLoader.load(K), valueLoader must not return null; it may either return a non-null value or throw an exception.

Throws:

ExecutionException - if a checked exception was thrown while loading the value

UncheckedExecutionException - if an unchecked exception was thrown while loading the value

ExecutionError - if an error was thrown while loading the value

Since:

11.0

getAllPresent

ImmutableMap<K,V> getAllPresent(Iterable<? extends K> keys)

Returns a map of the values associated with keys in this cache. The returned map will only contain entries which are already present in the cache.

Since:

11.0

put

void put(K key,
         V value)

Associates value with key in this cache. If the cache previously contained a value associated with key, the old value is replaced by value.

Prefer get(Object, Callable) when using the conventional "if cached, return; otherwise create, cache and return" pattern.

Since:

11.0

invalidate

void invalidate(Object key)

Discards any cached value for key key.

invalidateAll

void invalidateAll(Iterable<?> keys)

Discards any cached values for keys keys.

Since:

11.0

invalidateAll

void invalidateAll()

Discards all entries in the cache.

size

long size()

Returns the approximate number of entries in this cache.

stats

CacheStats stats()

Returns a current snapshot of this cache's cumulative statistics. All stats are initialized to zero, and are monotonically increasing over the lifetime of the cache.

asMap

ConcurrentMap<K,V> asMap()

Returns a view of the entries stored in this cache as a thread-safe map. Modifications made to the map directly affect the cache.

cleanUp

void cleanUp()

Performs any pending maintenance operations needed by the cache. Exactly which activities are performed -- if any -- is implementation-dependent.

get

@Deprecated
V get(K key)
      throws ExecutionException

Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).

Returns the value associated with key in this cache, first loading that value if necessary. No observable state associated with this cache is modified until loading completes.

Throws:

ExecutionException - if a checked exception was thrown while loading the value

UncheckedExecutionException - if an unchecked exception was thrown while loading the value

ExecutionError - if an error was thrown while loading the value

getUnchecked

@Deprecated
V getUnchecked(K key)

Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).

Returns the value associated with key in this cache, first loading that value if necessary. No observable state associated with this cache is modified until computation completes. Unlike get(K, java.util.concurrent.Callable), this method does not throw a checked exception, and thus should only be used in situations where checked exceptions are not thrown by the cache loader.

Warning: this method silently converts checked exceptions to unchecked exceptions, and should not be used with cache loaders which throw checked exceptions.

Throws:

UncheckedExecutionException - if an exception was thrown while loading the value, regardless of whether the exception was checked or unchecked

ExecutionError - if an error was thrown while loading the value

apply

@Deprecated
V apply(K key)

Deprecated. This method has been split out into the LoadingCache interface, and will be removed from Cache in Guava release 12.0. Note that CacheBuilder.build(CacheLoader) now returns a LoadingCache, so this deprecation (migration) can be dealt with by simply changing the type of references to the results of CacheBuilder.build(CacheLoader).

Discouraged. Provided to satisfy the Function interface; use get(K, java.util.concurrent.Callable) or getUnchecked(K) instead.

Specified by:

apply in interface Function<K,V>

Throws:

UncheckedExecutionException - if an exception was thrown while loading the value, regardless of whether the exception was checked or unchecked

ExecutionError - if an error was thrown while loading the value