org.kocakosm.pitaya.collection

Class Iterators

java.lang.Object

org.kocakosm.pitaya.collection.Iterators

public final class Iterators
extends Object

Static utility methods that operate on or return Iterators.

Author:

Osman KOCAK

Field Summary

Fields

Modifier and Type	Field and Description
static Iterator	EMPTY_ITERATOR The empty Iterator.

Method Summary

Methods

Modifier and Type	Method and Description
static <E> Iterator<E>	concat(Iterator<? extends E>... iterators) Concatenates all the given Iterators into a single one.
static <E> Iterator<E>	concat(Iterator<? extends Iterator<? extends E>> iterators) Concatenates all the given Iterators into a single one.
static <E> Iterator<E>	cycle(E... elements) Returns an Iterator that cycles indefinitely over the given elements.
static <E> Iterator<E>	cycle(Iterator<? extends E> iterator) Returns an Iterator that cycles indefinitely over the content of the given source Iterator.
static <E> Iterator<E>	emptyIterator() Returns the empty Iterator for a particular type (type-safe).
static boolean	equal(Iterator<?> i1, Iterator<?> i2) Returns whether the given Iterators contain equal elements in the same order.
static <E> Iterator<E>	limit(Iterator<? extends E> iterator, int limit) Creates an Iterator returning only the first limit elements of the given Iterator.
static int	skip(Iterator<?> iterator, int n) Skips n elements from the given Iterator.
static <E> Bag<E>	toBag(Iterator<? extends E> iterator) Returns a Bag containing all the given Iterator's elements.
static <E> List<E>	toList(Iterator<? extends E> iterator) Returns a List containing all the given Iterator's elements.
static <E> Set<E>	toSet(Iterator<? extends E> iterator) Returns a Set containing all the given Iterator's elements.
static String	toString(Iterator<?> iterator) Returns a String representation of the given Iterator, using the "[e1, e2, ..., en]" format.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_ITERATOR

public static final Iterator EMPTY_ITERATOR

The empty Iterator.

Method Detail

emptyIterator

public static <E> Iterator<E> emptyIterator()

Returns the empty Iterator for a particular type (type-safe). Note that unlike this method, the like-named static field does not provide type safety.

Type Parameters:

E - the type of the Iterator's elements.

Returns:

the empty Iterator.

concat

public static <E> Iterator<E> concat(Iterator<? extends E>... iterators)

Concatenates all the given Iterators into a single one. The source Iterators aren't polled until necessary. The returned Iterator supports Iterator.remove() when the corresponding input Iterator supports it.

Type Parameters:

E - the type of the returned Iterator's elements.

Parameters:

iterators - the Iterators to concatenate.

Returns:

the concatenated Iterator.

Throws:

NullPointerException - if iterators is null or if it contains a null reference.

concat

public static <E> Iterator<E> concat(Iterator<? extends Iterator<? extends E>> iterators)

Concatenates all the given Iterators into a single one. The source Iterators aren't polled until necessary. The returned Iterator supports Iterator.remove() when the corresponding input Iterator supports it.

Type Parameters:

E - the type of the returned Iterator's elements.

Parameters:

iterators - the Iterators to concatenate.

Returns:

the concatenated Iterator.

Throws:

NullPointerException - if iterators is null or if it contains a null reference.

cycle

public static <E> Iterator<E> cycle(Iterator<? extends E> iterator)

Returns an Iterator that cycles indefinitely over the content of the given source Iterator. The source Iterator is not polled until necessary. The returned Iterator supports Iterator.remove().

Type Parameters:

E - the type of the returned Iterator's elements.

Parameters:

iterator - the source Iterator.

Returns:

the cyclic Iterator.

Throws:

NullPointerException - if iterator is null.

cycle

public static <E> Iterator<E> cycle(E... elements)

Returns an Iterator that cycles indefinitely over the given elements. The returned Iterator supports Iterator.remove().

Type Parameters:

E - the type of the returned Iterator's elements.

Parameters:

elements - the elements to cycle over.

Returns:

the cyclic Iterator.

Throws:

NullPointerException - if elements is null.

equal

public static boolean equal(Iterator<?> i1,
            Iterator<?> i2)

Returns whether the given Iterators contain equal elements in the same order. Note that this method consumes entirely the input Iterators.

Parameters:

i1 - the first Iterator.

i2 - the second Iterator.

Returns:

whether the given Iterator have the same content.

limit

public static <E> Iterator<E> limit(Iterator<? extends E> iterator,
                    int limit)

Creates an Iterator returning only the first limit elements of the given Iterator. The source Iterator is not polled until necessary. The returned Iterator supports Iterator.remove() if the source Iterator supports it.

Type Parameters:

E - the type of the returned Iterator's elements.

Parameters:

iterator - the Iterator to limit.

limit - the number of elements in the returned Iterator.

Returns:

the limited Iterator.

Throws:

NullPointerException - if iterator is null.

IllegalArgumentException - if (limit is negative.

skip

public static int skip(Iterator<?> iterator,
       int n)

Skips n elements from the given Iterator.

Parameters:

iterator - the Iterator.

n - the number of elements to skip.

Returns:

the actual number of elements that has been skipped.

Throws:

NullPointerException - if iterator is null.

IllegalArgumentException - if (n is negative.

toList

public static <E> List<E> toList(Iterator<? extends E> iterator)

Returns a List containing all the given Iterator's elements. This method consumes entirely the input Iterator.

Type Parameters:

E - the type of the returned List's elements.

Parameters:

iterator - the Iterator to consume.

Returns:

the List created from the given Iterator.

Throws:

NullPointerException - if iterator is null.

toSet

public static <E> Set<E> toSet(Iterator<? extends E> iterator)

Returns a Set containing all the given Iterator's elements. The returned Set has the same iteration order as the given Iterator. This method consumes entirely the input Iterator.

Type Parameters:

E - the type of the returned Set's elements.

Parameters:

iterator - the Iterator to consume.

Returns:

the Set created from the given Iterator.

Throws:

NullPointerException - if iterator is null.

toBag

public static <E> Bag<E> toBag(Iterator<? extends E> iterator)

Returns a Bag containing all the given Iterator's elements. The returned Bag has the same iteration order as the given Iterator. This method consumes entirely the input Iterator.

Type Parameters:

E - the type of the returned Bag's elements.

Parameters:

iterator - the Iterator to consume.

Returns:

the Bag created from the given Iterator.

Throws:

NullPointerException - if iterator is null.

toString

public static String toString(Iterator<?> iterator)

Returns a String representation of the given Iterator, using the "[e1, e2, ..., en]" format. This method consumes entirely the input Iterator.

Parameters:

iterator - the Iterator.

Returns:

the String created from the given Iterator.

Throws:

NullPointerException - if iterator is null.