JHCaching

LRU caching map is Least Recent Used Map, (see Wiki), meaning that a Key,Value pair is stored in the cache, with a "expireTime", but every time the Key is retrieved (get method) the expire time is extended.
It is a simple POJO one jar library.
With complete documentation with examples and javadoc.

When the cache reaches is "maxSize" or a cleanup of the cache is performed (automatically by deamon thread dependent on the "LRUCachingMapConfiguration"),
it is the keys with least recent used (lowest expire time) that is discarded first.

This library has extended configuration, so you have the ability to set how times a keys expired time can be extended.
See more about the configuration abilities at Configuration.


Additionally this library has "ValueManager" interface, which wraps how the Value is stored.
This can be in Memory or in a Persistent storage like File, FileReference or Database which will give ability to restore the cache.