org.eclipse.persistence.annotations
Enum CacheType

java.lang.Object
  java.lang.Enum<CacheType>
      org.eclipse.persistence.annotations.CacheType

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable<CacheType>

public enum CacheType
extends java.lang.Enum<CacheType>

The CacheType enum is used with the Cache annotation for a persistent class. It defines the type of IdentityMap/Cache used for the class. By default the SOFT_WEAK cache type is used.

See Also:

Cache

Author:

Guy Pelletier

Since:

Oracle TopLink 11.1.1.0.0

Enum Constant Summary

CACHE
A cache identity map maintains a fixed number of objects specified by the application.

FULL
Provides full caching and guaranteed identity.

HARD_WEAK
Identical to the soft cache weak (SOFT_WEAK) identity map except that it uses hard references in the sub-cache.

NONE
WARNING: Does not preserve object identity and does not cache objects.

SOFT
Similar to the FULL identity map except that the map holds the objects using soft references.

SOFT_WEAK
Similar to the WEAK identity map except that it maintains a most-frequently-used sub-cache.

WEAK
Similar to the FULL identity map except that the map holds the objects using weak references.

Method Summary

static CacheType	valueOf(java.lang.String name) Returns the enum constant of this type with the specified name.
static CacheType[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

FULL

public static final CacheType FULL

Provides full caching and guaranteed identity. Caches all objects and does not remove them. WARNING: This method may be memory intensive when many objects are read.

WEAK

public static final CacheType WEAK

Similar to the FULL identity map except that the map holds the objects using weak references. This method allows full garbage collection and provides full caching and guaranteed identity.

SOFT

public static final CacheType SOFT

Similar to the FULL identity map except that the map holds the objects using soft references. This method allows full garbage collection when memory is low and provides full caching and guaranteed identity.

SOFT_WEAK

public static final CacheType SOFT_WEAK

Similar to the WEAK identity map except that it maintains a most-frequently-used sub-cache. The size of the sub-cache is proportional to the size of the identity map as specified by descriptor's setIdentityMapSize() method. The sub-cache uses soft references to ensure that these objects are garbage-collected only if the system is low on memory.

HARD_WEAK

public static final CacheType HARD_WEAK

Identical to the soft cache weak (SOFT_WEAK) identity map except that it uses hard references in the sub-cache. Use this identity map if soft references do not behave properly on your platform.

CACHE

public static final CacheType CACHE

A cache identity map maintains a fixed number of objects specified by the application. Objects are removed from the cache on a least-recently-used basis. This method allows object identity for the most commonly used objects. WARNING: Furnishes caching and identity, but does not guarantee identity.

NONE

public static final CacheType NONE

WARNING: Does not preserve object identity and does not cache objects.

Method Detail

values

public static CacheType[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (CacheType c : CacheType.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static CacheType valueOf(java.lang.String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

java.lang.IllegalArgumentException - if this enum type has no constant with the specified name

java.lang.NullPointerException - if the argument is null