javax.jdo

Interface Extent<E>

All Superinterfaces:

AutoCloseable, Iterable<E>

public interface Extent<E>
extends AutoCloseable, Iterable<E>

Instances of the Extent class represent the entire collection of instances in the data store of the candidate class or interface possibly including its subclasses or subinterfaces.

The Extent instance has two possible uses:

1. to iterate all instances of a particular class or interface
2. to execute a Query in the data store over all instances of a particular class or interface

Method Summary

Modifier and Type	Method and Description
void	close() Don't use this method directly; use closeAll() instead.
void	close(Iterator<E> it) Close an Iterator associated with this Extent instance.
void	closeAll() Close all Iterators associated with this Extent instance.
Class<E>	getCandidateClass() An Extent contains all instances of a particular class or interface in the data store; this method returns the Class of the instances represented by this Extent.
FetchPlan	getFetchPlan() Get the fetch plan associated with this Extent.
PersistenceManager	getPersistenceManager() An Extent is managed by a PersistenceManager; this method gives access to the owning PersistenceManager.
boolean	hasSubclasses() Returns whether this Extent was defined to contain subclasses.
Iterator<E>	iterator() Returns an iterator over all the instances in the Extent.

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

iterator

Iterator<E> iterator()

Returns an iterator over all the instances in the Extent. The behaviour of the returned iterator might depend on the setting of the ignoreCache flag in the owning PersistenceManager.

Specified by:

iterator in interface Iterable<E>

Returns:

an iterator over all instances in the Extent

hasSubclasses

boolean hasSubclasses()

Returns whether this Extent was defined to contain subclasses.

Returns:

true if this Extent was defined to contain instances that are of a subclass type.

getCandidateClass

Class<E> getCandidateClass()

An Extent contains all instances of a particular class or interface in the data store; this method returns the Class of the instances represented by this Extent.

Returns:

the Class of instances of this Extent.

getPersistenceManager

PersistenceManager getPersistenceManager()

An Extent is managed by a PersistenceManager; this method gives access to the owning PersistenceManager.

Returns:

the owning PersistenceManager

closeAll

void closeAll()

Close all Iterators associated with this Extent instance. Iterators closed by this method will return false to hasNext() and will throw NoSuchElementException on next(). The Extent instance can still be used as a parameter of Query.setExtent, and to get an Iterator.

close

void close(Iterator<E> it)

Close an Iterator associated with this Extent instance. Iterators closed by this method will return false to hasNext() and will throw NoSuchElementException on next(). The Extent instance can still be used as a parameter of Query.setExtent, and to get an Iterator.

Parameters:

it - an Iterator obtained by the method iterator() on this Extent instance.

close

void close()
    throws Exception

Don't use this method directly; use closeAll() instead. It is intended for use with try-with-resources.

Specified by:

close in interface AutoCloseable

Throws:

Exception - if this resource cannot be closed

getFetchPlan

FetchPlan getFetchPlan()

Get the fetch plan associated with this Extent.

Returns:

the fetch plan

Since:

2.0