javax.jdo
Interface Extent

public interface Extent

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

The Extent instance has two possible uses:

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

Version:

0.9

Author:

Craig Russell

Method Summary

void	close(java.util.Iterator it) Close an Iterator associated with this Extent instance.
void	closeAll() Close all Iterators associated with this Extent instance.
java.lang.Class	getCandidateClass() An Extent contains all instances of a particular class in the data store; this method returns the Class of the instances.
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.
java.util.Iterator	iterator() Returns an iterator over all the instances in the Extent.

Method Detail

iterator

public java.util.Iterator iterator()

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

Returns:

an iterator over all instances in the Extent

hasSubclasses

public 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

public java.lang.Class getCandidateClass()

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

Returns:

the Class of instances of this Extent.

getPersistenceManager

public PersistenceManager getPersistenceManager()

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

Returns:

the owning PersistenceManager

closeAll

public 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

public void close(java.util.Iterator 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.