Class SoftCache<K,V,D>

java.lang.Object
com.ibm.icu.impl.CacheBase<K,V,D>
com.ibm.icu.impl.SoftCache<K,V,D>
Type Parameters:
K - Cache lookup key type
V - Cache instance value type (must not be a CacheValue)
D - Data type for creating a new instance value
Direct Known Subclasses:
Calendar.WeekDataCache, ICUResourceBundleReader.ReaderCache, TimeZoneFormat.TimeZoneFormatCache, TimeZoneGenericNames.Cache, TimeZoneNames.Cache, TimeZoneNamesImpl.MZ2TZsCache, TimeZoneNamesImpl.TZ2MZsCache, ZoneMeta.CustomTimeZoneCache, ZoneMeta.SystemTimeZoneCache
public abstract class SoftCache<K,V,D> extends CacheBase<K,V,D>
Generic, thread-safe cache implementation, usually storing cached instances in References via CacheValues. To use, instantiate a subclass which implements the createInstance() method, and call get() with the key and the data. The get() call will use the data only if it needs to call createInstance(), otherwise the data is ignored.

When caching instances while the CacheValue "strength" is SOFT, the Java runtime can later release these instances once they are not used any more at all. If such an instance is then requested again, the getInstance() method will call createInstance() again and reset the CacheValue. The cache holds on to its map of keys to CacheValues forever.

A value can be null if createInstance() returns null. In this case, it must do so consistently for the same key and data.

  • Field Details

  • Constructor Details

    • SoftCache

      public SoftCache()

  • Method Details

    • getMap

      protected ConcurrentHashMap<K,Object> getMap()
      Returns:
      the cache contents.

    • getInstance

      public final V getInstance(K key, D data)
      Description copied from class: CacheBase
      Retrieves an instance from the cache. Calls createInstance(key, data) if the cache does not already contain an instance with this key. Ignores data if the cache already contains an instance with this key.
      Specified by:
      getInstance in class CacheBase<K,V,D>
      Parameters:
      key - Cache lookup key for the requested instance
      data - Data for createInstance() if the instance is not already cached
      Returns:
      The requested instance