de.unidu.is.util
Class SequenceIterator

java.lang.Object
  de.unidu.is.util.SequenceIterator

All Implemented Interfaces:

java.util.Iterator

public abstract class SequenceIterator

extends java.lang.Object

implements java.util.Iterator

A iterator that is a sequence of several iterators.

The sequence iterator has an iterator returning objects which can deliver iterators. The delivered iterators are traversed one after another by this iterator.

Since:

2001-06-29

Version:

$Revision: 1.6 $, $Date: 2005/02/28 22:27:55 $

Author:

Henrik Nottelmann

Field Summary

protected boolean	called Indicates if next() has ever been called.
protected java.util.Iterator	currentIterator The current iterator producing items which are returned by this class.
protected java.util.Iterator	iterator The iterator returning objects which can deliver iterators.
protected java.lang.Object	next The next object to be returned.

Constructor Summary

SequenceIterator(java.util.Iterator iterator)
Creates a new sequence iterator.

Method Summary

protected void	calcNext() Calculates the next object to be returned.
abstract java.util.Iterator	createIterator(java.lang.Object object) Calls the speicified object to create an iterator.
boolean	hasNext() Returns true if this iterator has more elements.
java.lang.Object	next() Returns the next object.
void	remove() Removing objects is unsupported!

Methods inherited from class java.lang.Object

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

Field Detail

iterator

protected java.util.Iterator iterator

The iterator returning objects which can deliver iterators.

currentIterator

protected java.util.Iterator currentIterator

The current iterator producing items which are returned by this class.

next

protected java.lang.Object next

The next object to be returned.

called

protected boolean called

Indicates if next() has ever been called. This is needed for initialisation outside the constructor (because that does not work!).

Constructor Detail

SequenceIterator

public SequenceIterator(java.util.Iterator iterator)

Creates a new sequence iterator.

Parameters:

iterator - iterator returning objects which can deliver iterators

Method Detail

hasNext

public boolean hasNext()

Returns true if this iterator has more elements.

Specified by:

hasNext in interface java.util.Iterator

Returns:

true if the iterator has more elements

next

public java.lang.Object next()

Returns the next object.

Specified by:

next in interface java.util.Iterator

Returns:

next object

Throws:

java.util.NoSuchElementException - if there is no object available

calcNext

protected void calcNext()

Calculates the next object to be returned.

createIterator

public abstract java.util.Iterator createIterator(java.lang.Object object)

Calls the speicified object to create an iterator. This method has to be overridden!

Parameters:

object - object which should create an iterator

Returns:

iterator

remove

public void remove()

Removing objects is unsupported!

Specified by:

remove in interface java.util.Iterator