Purpose: This class is a configuration property used to specify
What type of Referenes EclipseLink will use when referencing Entities
within the Persistence Context / UnitOfWork. Depending on the configured
ReferenceMode some Entities may be garbage collected.
References to Objects will be through hard references. These objects will not be available for
garbage collection until the referencing artifact (usually a Persistence Context or UnitOfWork)
released or closed.
References to Objects that support active attribute change tracking
(enabled through weaving or by the developer)will be held by weak
references. This means any of afore mentioned objects no longer referenced directly or
indirectly will be available for garbage collection. If the object is
gc'd before the EM/UnitOfWork flushes to the database then this object
and any others like it will not be checked for changes. When a change is
made to a change tracked object that object is moved to a hard reference
and will not be available for GC until flushed. New and removed objects
are also held by hard references. Non change tracked objects will always
be held by "hard" references and are not available for GC. This is the
default mode for EclipsLink. See:
Same as weak reference except Objects that can not be changed
tracked (Deferred Change Detection) will not be prevented from being
garbage collected. This may result in a loss of changes if a changed object
is removed before being flushed to the database.
When a change is made to a change tracked object that object
is moved to a hard reference and will not be available for GC until
flushed. New and removed objects are also held by hard references until
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
name - the name of the enum constant to be returned.
the enum constant with the specified name
java.lang.IllegalArgumentException - if this enum type has no constant
with the specified name
java.lang.NullPointerException - if the argument is null