Cache (Guava: Google Core Libraries for Java 15.0 API)

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>
```
A semi-persistent mapping from keys to values. Cache entries are manually added using get(Object, Callable) or put(Object, Object), and are stored in the cache until either evicted or manually invalidated.
Implementations of this interface are expected to be thread-safe, and can be safely accessed by multiple concurrent threads.
Note that while this class is still annotated as Beta, the API is frozen from a consumer's standpoint. In other words existing methods are all considered non-Beta and won't be changed without going through an 18 month deprecation cycle; however new methods may be added at any time.

Since:

10.0

Author:

Charles Fry

Method Summary

Methods
Modifier and Type	Method and Description
`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, 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<?> keys)` Returns a map of the values associated with `keys` in this cache.
`V`	`getIfPresent(Object key)` Returns the value associated with `key` in this cache, or `null` if there is no cached value for `key`.
`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.
`void`	`putAll(Map<? extends K,? extends V> m)` Copies all of the mappings from the specified map to the cache.
`long`	`size()` Returns the approximate number of entries in this cache.
`CacheStats`	`stats()` Returns a current snapshot of this cache's cumulative statistics.

- Method Detail
  - getIfPresent
```
@Nullable
V getIfPresent(Object 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<?> 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
  - putAll
```
void putAll(Map<? extends K,? extends V> m)
```
    Copies all of the mappings from the specified map to the cache. The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.
    
    Since:
    
    12.0
  - 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.

Interface Cache<K,V>

Method Summary

Method Detail

getIfPresent

get

getAllPresent

put

putAll

invalidate

invalidateAll

invalidateAll

size

stats

asMap

cleanUp