info.aduna.iteration

Class DelayedIteration<E,X extends Exception>

java.lang.Object

info.aduna.iteration.CloseableIterationBase<E,X>

info.aduna.iteration.DelayedIteration<E,X>

All Implemented Interfaces:

CloseableIteration<E,X>, Iteration<E,X>

public abstract class DelayedIteration<E,X extends Exception>
extends CloseableIterationBase<E,X>

An iteration that delays the creation of the underlying iteration until it is being accessed. This is mainly useful for situations where iteration creation adds considerable overhead but where the iteration may not actually be used, or where a created iteration consumes scarce resources like JDBC-connections or memory. Subclasses must implement the createIteration method, which is called once when the iteration is first needed.

Constructor Summary

Constructors

Constructor and Description
DelayedIteration() Creates a new DelayedIteration.

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract Iteration<? extends E,? extends X>	createIteration() Creates the iteration that should be iterated over.
protected void	handleClose() Closes this iteration as well as the underlying iteration if it has already been created and happens to be a CloseableIteration.
boolean	hasNext() Calls the hasNext method of the underlying iteration.
E	next() Calls the next method of the underlying iteration.
void	remove() Calls the remove method of the underlying iteration.

Methods inherited from class info.aduna.iteration.CloseableIterationBase

close, isClosed

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DelayedIteration

public DelayedIteration()

Creates a new DelayedIteration.

Method Detail

createIteration

protected abstract Iteration<? extends E,? extends X> createIteration()
                                                                                 throws X extends Exception

Creates the iteration that should be iterated over. This method is called only once, when the iteration is first needed.

Throws:

X extends Exception

hasNext

public boolean hasNext()
                throws X extends Exception

Calls the hasNext method of the underlying iteration.

Returns:

true if the iteration has more elements.

Throws:

X

X extends Exception

next

public E next()
       throws X extends Exception

Calls the next method of the underlying iteration.

Returns:

the next element in the iteration.

Throws:

X extends Exception

remove

public void remove()
            throws X extends Exception

Calls the remove method of the underlying iteration.

Throws:

X extends Exception

handleClose

protected void handleClose()
                    throws X extends Exception

Closes this iteration as well as the underlying iteration if it has already been created and happens to be a CloseableIteration.

Overrides:

handleClose in class CloseableIterationBase<E,X extends Exception>

Throws:

X

X extends Exception