Package generic.util

Class MultiIterator<T>

java.lang.Object

generic.util.MultiIterator<T>

Type Parameters:

T - the type of this iterator

All Implemented Interfaces:

Iterator<T>

public class MultiIterator<T>
extends Object
implements Iterator<T>

An iterator that is comprised of one or more PeekableIterators. The type T of the the iterators must either implement Comparable directly or you must provide a Comparator for comparing the types. Further, it is assumed that the iterators return values in sorted order. If the sorted order is reversed, then that must be indicated in the constructor of this class.

This class allows duplicate items in the iterators. Thus, if you do not wish to process duplicate values, then you need to de-dup the data returned from next(). Alternatively, you could subclass this iterator and de-dup the returned values.

This class also does not handle null items returned during the iteration process.

Field Summary

Fields

Modifier and Type	Field	Description
protected List<PeekableIterator<T>>	iterators

Constructor Summary

Constructors

Constructor	Description
MultiIterator(List<PeekableIterator<T>> iterators, boolean forward)	Use this constructor when the items of the iterators are naturally comparable (i.e., they implement Comparable).
MultiIterator(List<PeekableIterator<T>> iterators, Comparator<T> comparator, boolean forward)	Use this constructor when the items of the iterators are not naturally comparable (i.e., they do not implement Comparable).

Method Summary

Modifier and Type	Method	Description
boolean	hasNext()
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

Field Details

iterators

protected List<PeekableIterator<T>> iterators

Constructor Details

MultiIterator

public MultiIterator(List<PeekableIterator<T>> iterators,
 boolean forward)

Use this constructor when the items of the iterators are naturally comparable (i.e., they implement Comparable).

Parameters:

iterators - the iterators that provide the data

forward - true if the iterators provide data sorted ascending; false for descending

MultiIterator

public MultiIterator(List<PeekableIterator<T>> iterators,
 Comparator<T> comparator,
 boolean forward)

Use this constructor when the items of the iterators are not naturally comparable (i.e., they do not implement Comparable).

Parameters:

iterators - the iterators that provide the data

comparator - the comparator used to find the next item

forward - true if the iterators provide data sorted ascending; false for descending

Method Details

remove

public void remove()

Specified by:

remove in interface Iterator<T>

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<T>

next

public T next()

Specified by:

next in interface Iterator<T>