11.2 State Interrogation

The JDOHelper class provides the following methods to interrogate the state of an instance:

static boolean isPersistent(Object obj);
static boolean isTransactional(Object obj);
static boolean isDirty(Object obj);
static boolean isNew(Object obj);
static boolean isDeleted(Object obj);

Each of these methods returns false if the instance is null, transient, or of a class that is not persistent. Otherwise, these methods return the following:

isPersistent( )

Returns true for an instance that represents a persistent object in the datastore

isTransactional( )

Returns true for an instance whose state is associated with the current transaction

isDirty( )

Returns true for an instance whose state has changed in the current transaction

isNew( )

Returns true for an instance made persistent in the current transaction

isDeleted( )

Returns true if the instance has been deleted in the current transaction

Table 11-1 specifies the values these methods return for each required lifecycle state. You could write a method that calls each of these methods and returns a String denoting the instance's lifecycle state. This can be useful if you are debugging or would like to know the lifecycle state of instances.

false

false

false

false

false

true

false

false

false

false

true

true

true

true

false

true

true

false

false

false

true

true

true

false

false

true

true

true

false

true

true

true

true

true

true

Table A-1 in Appendix A provides a complete listing of the values these methods return for all the lifecycle states.