state of the objects

Transient - an object is transient if it has just been instantiated using the new operator, and it has no persistent representation in the file. Transient instances will be destroyed by the garbage collector if the application doesn't hold a reference anymore.
To be persisted - an object have its state when it is newly referenced by an object having persistent state or to be persisted state, also when add to persitent objet pool ( IDataAccessSession#setObject )
Persistent - a persistent instance has a representation in the file. It has been loaded. JOAFIP will detect any changes made to an object in persistent state and synchronize the state with the file when saving.
Detached - a detached instance is an object that has been persistent, but close done ( saving or not ). The reference to the object is still valid, of course, but not usable since detached from data access session.

Making transient objects persistent, assuming "IDataAccessSession dataAccessSession=filePersistence.createDataAccessSession()"

dataAccessSession.open()

MyClass myEntity=new MyClas(....)

IDataAccessSession.setObject(key,myEntity)

dataAccessSession.close(EnumFilePersistenceCloseAction.SAVE),

dataAccessSession.open()

MyRootClass root=dataAccessSession.getObject(key)

MyClass myEntity=new MyClas(....)

root.set(myEntity), supposing set method make root object referencing myEntity object.

dataAccessSession.close(EnumFilePersistenceCloseAction.SAVE),

Loading a object

IDataAccessSession.open()

by getting a root object using MyRootClass root=dataAccessSession.getObject(key)

getting object in relation with root, like MyClass myEntity=root.get(...)

dataAccessSession.close( save or not )

Below the object persistent state transition diagram:

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