cz.auderis.tools.collection.iterator

Class IndexedIteratorDecorator<T>

java.lang.Object

cz.auderis.tools.collection.iterator.IndexedIteratorDecorator<T>

Type Parameters:

T - type of iterated elements

All Implemented Interfaces:

Iterable<T>, Iterator<T>

public class IndexedIteratorDecorator<T>
extends Object
implements Iterator<T>, Iterable<T>

Decorator of another iterator that provides numeric index of the current item within iterated collection. Additionally, a "true index" that denotes current iteration cycle, is available as well.

The difference between "normal" and "true" index becomes clear when remove() is invoked - in the next iteration cycle, the true index is normally incremented, but the normal index keeps the previous value. Assume the following sample:

     IndexedIteratorDecorator iter = ...
     ...
     iter.next();
     int normalIndex1 = iter.getIndex();
     int trueIndex1 = iter.getTrueIndex();
     iter.remove();
     iter.next();
     int normalIndex2 = iter.getIndex();
     int trueIndex2 = iter.getTrueIndex();
 

Due to remove(), the following relations are valid:

• normalIndex1 == normalIndex2
• trueIndex1 + 1 == trueIndex2

Version:

1.0

Author:

Boleslav Bobcik <bbobcik@gmail.com>

Constructor Summary

Constructors

Constructor and Description
IndexedIteratorDecorator(Iterator<? extends T> baseIter) Creates a new instance of the decorator.

Method Summary

Modifier and Type	Method and Description
int	getIndex() Returns an index of the current element in the iterated collection.
int	getTrueIndex() Returns a "true" index of the current iteration cycle.
boolean	hasNext()
Iterator<T>	iterator()
T	next()
void	remove()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

IndexedIteratorDecorator

public IndexedIteratorDecorator(Iterator<? extends T> baseIter)

Creates a new instance of the decorator. If the argument is null, it is considered as an empty iterator.

Parameters:

baseIter - iterator to be decorated

Method Detail

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<T>

next

public T next()

Specified by:

next in interface Iterator<T>

remove

public void remove()

Specified by:

remove in interface Iterator<T>

getIndex

public int getIndex()

Returns an index of the current element in the iterated collection. Before iteration start the value is -1. With each next() that is not preceded by remove() the index value is incremented by 1.

Returns:

index of the current iterated element

getTrueIndex

public int getTrueIndex()

Returns a "true" index of the current iteration cycle. Before iteration start the value is -1 and with each next() its value is incremented by 1.

Returns:

index of the current iteration cycle