Iterators (Neo4j 3.4.0-alpha07 API)

java.lang.Object
- org.neo4j.helpers.collection.Iterators

```
public abstract class Iterators
extends Object
```
Contains common functionality regarding Iterators and Iterables.

Constructor Summary

Constructors
Constructor and Description

Iterators()

Constructors
Constructor and Description
`Iterators()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <C extends Collection<T>,T> C`	`addToCollection(Iterator<T> iterator, C collection)` Adds all the items in `iterator` to `collection`.
`static <C extends Collection<T>,T> C`	`addToCollectionUnique(Iterable<T> iterable, C collection)` Adds all the items in `iterator` to `collection`.
`static <C extends Collection<T>,T> C`	`addToCollectionUnique(Iterator<T> iterator, C collection)` Adds all the items in `iterator` to `collection`.
`static <T> T[]`	`array(T... items)`
`static <T> Collection<T>`	`asCollection(Iterator<T> iterable)`
`static <T> Iterable<T>`	`asIterable(Iterator<T> iterator)` Exposes `iterator` as an `Iterable`.
`static Iterator<Integer>`	`asIterator(int... array)`
`static <T> Iterator<T>`	`asIterator(int maxItems, T... array)`
`static Iterator<Long>`	`asIterator(long... array)`
`static <T> List<T>`	`asList(Iterator<T> iterator)`
`static <T,EX extends Exception> List<T>`	`asList(org.neo4j.collection.RawIterator<T,EX> iterator)`
`static <T,EX extends Exception> org.neo4j.collection.RawIterator<T,EX>`	`asRawIterator(Iterator<T> iter)`
`static <T> org.neo4j.graphdb.ResourceIterable<T>`	`asResourceIterable(org.neo4j.graphdb.ResourceIterator<T> it)`
`static <T> org.neo4j.graphdb.ResourceIterator<T>`	`asResourceIterator(Iterator<T> iterator)`
`static <T> Set<T>`	`asSet(Iterator<T> iterator)`
`static <T> Set<T>`	`asSet(T... items)` Creates a `Set` from an array of items.an
`static <T> Set<T>`	`asUniqueSet(Iterator<T> items)` Creates a `Set` from an array of items.
`static <T> Set<T>`	`asUniqueSet(T... items)` Creates a `Set` from an array of items.
`static <T> Iterator<T>`	`concat(Iterator<? extends T>... iterators)`
`static <T> Iterator<T>`	`concat(Iterator<Iterator<T>> iterators)`
`static <T> org.neo4j.graphdb.ResourceIterator<T>`	`concatResourceIterators(Iterator<org.neo4j.graphdb.ResourceIterator<T>> iterators)`
`static <T> boolean`	`contains(Iterator<T> iterator, T item)`
`static <T> long`	`count(Iterator<T> iterator)`
`static <T> long`	`count(Iterator<T> iterator, Predicate<T> filter)` Counts the number of filtered in the `iterator` by looping through it.
`static <T> org.neo4j.graphdb.ResourceIterator<T>`	`emptyResourceIterator()`
`static <X> Iterator<X>`	`filter(Predicate<? super X> specification, Iterator<X> i)`
`static <T> T`	`first(Iterator<T> iterator)` Returns the given iterator's first element.
`static <T> T`	`firstOrNull(Iterator<T> iterator)` Returns the given iterator's first element or `null` if no element found.
`static <FROM,TO> Iterator<TO>`	`flatMap(Function<? super FROM,? extends Iterator<TO>> function, Iterator<FROM> from)`
`static <T> T`	`fromEnd(Iterator<T> iterator, int n)` Returns the iterator's n:th item from the end of the iteration.
`static <T> T`	`fromEndOrNull(Iterator<T> iterator, int n)` Returns the iterator's n:th item from the end of the iteration.
`static <T> Iterator<T>`	`iterator(int maxItems, T... items)`
`static <T> Iterator<T>`	`iterator(T... items)`
`static <T> Iterator<T>`	`iterator(T item)`
`static boolean`	`iteratorsEqual(Iterator<?> first, Iterator<?> other)` Iterates over the full iterators, and checks equality for each item in them.
`static String`	`join(String joinString, Iterator<?> iter)`
`static <T> T`	`last(Iterator<T> iterator)` Returns the given iterator's last element.
`static <T> T`	`lastOrNull(Iterator<T> iterator)` Returns the given iterator's last element or `null` if no element found.
`static <T> Iterable<T>`	`loop(Iterator<T> iterator)` Convenience method for looping over an `Iterator`.
`static <FROM,TO> Iterator<TO>`	`map(Function<? super FROM,? extends TO> function, Iterator<FROM> from)`
`static <FROM,TO,EX extends Exception> org.neo4j.collection.RawIterator<TO,EX>`	`map(org.neo4j.function.ThrowingFunction<? super FROM,? extends TO,EX> function, org.neo4j.collection.RawIterator<FROM,EX> from)`
`static <T> PrefetchingIterator<T>`	`prefetching(Iterator<T> iterator)`
`static <T> org.neo4j.graphdb.ResourceIterator<T>`	`resourceIterator(Iterator<T> iterator, org.neo4j.graphdb.Resource resource)`
`static <T> Set<T>`	`set(T... items)` Alias for asSet()
`static <T> T`	`single(Iterator<T> iterator)` Returns the given iterator's single element.
`static <T> T`	`single(Iterator<T> iterator, T itemIfNone)` Returns the given iterator's single element or `itemIfNone` if no element found.
`static <T> T`	`singleOrNull(Iterator<T> iterator)` Returns the given iterator's single element or `null` if no element found.
`static <T> Stream<T>`	`stream(Iterator<T> iterator)` Create a stream from the given iterator.
`static <T> Stream<T>`	`stream(Iterator<T> iterator, int characteristics)` Create a stream from the given iterator with given characteristics.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Iterators
```
public Iterators()
```
- Method Detail
  - firstOrNull
```
public static <T> T firstOrNull(Iterator<T> iterator)
```
    Returns the given iterator's first element or null if no element found.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the first element in the iterator, or null if no element found.
  - first
```
public static <T> T first(Iterator<T> iterator)
```
    Returns the given iterator's first element. If no element is found a NoSuchElementException is thrown.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the first element in the iterator.
    
    Throws:
    
    NoSuchElementException - if no element found.
  - lastOrNull
```
public static <T> T lastOrNull(Iterator<T> iterator)
```
    Returns the given iterator's last element or null if no element found.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the last element in the iterator, or null if no element found.
  - last
```
public static <T> T last(Iterator<T> iterator)
```
    Returns the given iterator's last element. If no element is found a NoSuchElementException is thrown.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the last element in the iterator.
    
    Throws:
    
    NoSuchElementException - if no element found.
  - singleOrNull
```
public static <T> T singleOrNull(Iterator<T> iterator)
```
    Returns the given iterator's single element or null if no element found. If there is more than one element in the iterator a NoSuchElementException will be thrown. If the iterator implements Resource it will be closed in a finally block after the single item has been retrieved, or failed to be retrieved.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the single element in iterator, or null if no element found.
    
    Throws:
    
    NoSuchElementException - if more than one element was found.
  - single
```
public static <T> T single(Iterator<T> iterator)
```
    Returns the given iterator's single element. If there are no elements or more than one element in the iterator a NoSuchElementException will be thrown. If the iterator implements Resource it will be closed in a finally block after the single item has been retrieved, or failed to be retrieved.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    Returns:
    
    the single element in the iterator.
    
    Throws:
    
    NoSuchElementException - if there isn't exactly one element.
  - fromEnd
```
public static <T> T fromEnd(Iterator<T> iterator,
                            int n)
```
    Returns the iterator's n:th item from the end of the iteration. If the iterator has got less than n-1 items in it NoSuchElementException is thrown.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    n - the n:th item from the end to get.
    
    Returns:
    
    the iterator's n:th item from the end of the iteration.
    
    Throws:
    
    NoSuchElementException - if the iterator contains less than n-1 items.
  - fromEndOrNull
```
public static <T> T fromEndOrNull(Iterator<T> iterator,
                                  int n)
```
    Returns the iterator's n:th item from the end of the iteration. If the iterator has got less than n-1 items in it null is returned.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    n - the n:th item from the end to get.
    
    Returns:
    
    the iterator's n:th item from the end of the iteration, or null if the iterator doesn't contain that many items.
  - iteratorsEqual
```
public static boolean iteratorsEqual(Iterator<?> first,
                                     Iterator<?> other)
```
    Iterates over the full iterators, and checks equality for each item in them. Note that this will consume the iterators.
    
    Parameters:
    
    first - the first iterator
    
    other - the other iterator
    
    Returns:
    
    true if all items are equal; otherwise
  - single
```
public static <T> T single(Iterator<T> iterator,
                           T itemIfNone)
```
    Returns the given iterator's single element or itemIfNone if no element found. If there is more than one element in the iterator a NoSuchElementException will be thrown. If the iterator implements Resource it will be closed in a finally block after the single item has been retrieved, or failed to be retrieved.
    
    Type Parameters:
    
    T - the type of elements in iterator.
    
    Parameters:
    
    iterator - the Iterator to get elements from.
    
    itemIfNone - item to use if none is found
    
    Returns:
    
    the single element in iterator, or itemIfNone if no element found.
    
    Throws:
    
    NoSuchElementException - if more than one element was found.
  - addToCollection
```
public static <C extends Collection<T>,T> C addToCollection(Iterator<T> iterator,
                                                            C collection)
```
    Adds all the items in iterator to collection.
    
    Type Parameters:
    
    C - the type of Collection to add to items to.
    
    T - the type of items in the collection and iterator.
    
    Parameters:
    
    iterator - the Iterator to grab the items from.
    
    collection - the Collection to add the items to.
    
    Returns:
    
    the collection which was passed in, now filled with the items from iterator.
  - addToCollectionUnique
```
public static <C extends Collection<T>,T> C addToCollectionUnique(Iterator<T> iterator,
                                                                  C collection)
```
    Adds all the items in iterator to collection.
    
    Type Parameters:
    
    C - the type of Collection to add to items to.
    
    T - the type of items in the collection and iterator.
    
    Parameters:
    
    iterator - the Iterator to grab the items from.
    
    collection - the Collection to add the items to.
    
    Returns:
    
    the collection which was passed in, now filled with the items from iterator.
  - addToCollectionUnique
```
public static <C extends Collection<T>,T> C addToCollectionUnique(Iterable<T> iterable,
                                                                  C collection)
```
    Adds all the items in iterator to collection.
    
    Type Parameters:
    
    C - the type of Collection to add to items to.
    
    T - the type of items in the collection and iterator.
    
    Parameters:
    
    iterable - the Iterator to grab the items from.
    
    collection - the Collection to add the items to.
    
    Returns:
    
    the collection which was passed in, now filled with the items from iterator.
  - loop
```
public static <T> Iterable<T> loop(Iterator<T> iterator)
```
    Convenience method for looping over an Iterator. Converts the Iterator to an Iterable by wrapping it in an Iterable that returns the Iterator. It breaks the contract of Iterable in that it returns the supplied iterator instance for each call to iterator() on the returned Iterable instance. This method exists to make it easy to use an Iterator in a for-loop.
    
    Type Parameters:
    
    T - the type of items in the iterator.
    
    Parameters:
    
    iterator - the iterator to expose as an Iterable.
    
    Returns:
    
    the supplied iterator posing as an Iterable.
  - asIterable
```
public static <T> Iterable<T> asIterable(Iterator<T> iterator)
```
    Exposes iterator as an Iterable. It breaks the contract of Iterable in that it returns the supplied iterator instance for each call to iterator() on the returned Iterable instance. This method mostly exists to make it easy to use an Iterator in a for-loop.
    
    Type Parameters:
    
    T - the type of items in the iterator.
    
    Parameters:
    
    iterator - the iterator to expose as an Iterable.
    
    Returns:
    
    the supplied iterator posing as an Iterable.
  - count
```
public static <T> long count(Iterator<T> iterator)
```
  - count
```
public static <T> long count(Iterator<T> iterator,
                             Predicate<T> filter)
```
    Counts the number of filtered in the iterator by looping through it.
    
    Type Parameters:
    
    T - the type of items in the iterator.
    
    Parameters:
    
    iterator - the Iterator to count items in.
    
    filter - the filter to test items against
    
    Returns:
    
    the number of filtered items found in iterator.
  - asCollection
```
public static <T> Collection<T> asCollection(Iterator<T> iterable)
```
  - asList
```
public static <T> List<T> asList(Iterator<T> iterator)
```
  - asList
```
public static <T,EX extends Exception> List<T> asList(org.neo4j.collection.RawIterator<T,EX> iterator)
                                               throws EX extends Exception
```
    Throws:
    
    EX extends Exception
  - asSet
```
public static <T> Set<T> asSet(Iterator<T> iterator)
```
  - asSet
```
@SafeVarargs
public static <T> Set<T> asSet(T... items)
```
    Creates a Set from an array of items.an
    
    Type Parameters:
    
    T - the type of the items
    
    Parameters:
    
    items - the items to add to the set.
    
    Returns:
    
    the Set containing the items.
  - set
```
@SafeVarargs
public static <T> Set<T> set(T... items)
```
    Alias for asSet()
    
    Type Parameters:
    
    T - the type of the items
    
    Parameters:
    
    items - the items to add to the set.
    
    Returns:
    
    the Set containing the items.
  - asUniqueSet
```
@SafeVarargs
public static <T> Set<T> asUniqueSet(T... items)
```
    Creates a Set from an array of items.
    
    Type Parameters:
    
    T - the type of the items
    
    Parameters:
    
    items - the items to add to the set.
    
    Returns:
    
    the Set containing the items.
  - asUniqueSet
```
public static <T> Set<T> asUniqueSet(Iterator<T> items)
```
    Creates a Set from an array of items.
    
    Type Parameters:
    
    T - the type of the items
    
    Parameters:
    
    items - the items to add to the set.
    
    Returns:
    
    the Set containing the items.
  - asIterator
```
public static Iterator<Long> asIterator(long... array)
```
  - asIterator
```
public static Iterator<Integer> asIterator(int... array)
```
  - asIterator
```
@SafeVarargs
public static <T> Iterator<T> asIterator(int maxItems,
                                                      T... array)
```
  - iterator
```
public static <T> Iterator<T> iterator(T item)
```
  - iterator
```
@SafeVarargs
public static <T> Iterator<T> iterator(T... items)
```
  - iterator
```
@SafeVarargs
public static <T> Iterator<T> iterator(int maxItems,
                                                    T... items)
```
  - emptyResourceIterator
```
public static <T> org.neo4j.graphdb.ResourceIterator<T> emptyResourceIterator()
```
  - contains
```
public static <T> boolean contains(Iterator<T> iterator,
                                   T item)
```
  - asResourceIterator
```
public static <T> org.neo4j.graphdb.ResourceIterator<T> asResourceIterator(Iterator<T> iterator)
```
  - resourceIterator
```
public static <T> org.neo4j.graphdb.ResourceIterator<T> resourceIterator(Iterator<T> iterator,
                                                                         org.neo4j.graphdb.Resource resource)
```
  - array
```
@SafeVarargs
public static <T> T[] array(T... items)
```
  - filter
```
public static <X> Iterator<X> filter(Predicate<? super X> specification,
                                     Iterator<X> i)
```
  - map
```
public static <FROM,TO> Iterator<TO> map(Function<? super FROM,? extends TO> function,
                                         Iterator<FROM> from)
```
  - map
```
public static <FROM,TO,EX extends Exception> org.neo4j.collection.RawIterator<TO,EX> map(org.neo4j.function.ThrowingFunction<? super FROM,? extends TO,EX> function,
                                                                                         org.neo4j.collection.RawIterator<FROM,EX> from)
```
  - asRawIterator
```
public static <T,EX extends Exception> org.neo4j.collection.RawIterator<T,EX> asRawIterator(Iterator<T> iter)
```
  - flatMap
```
public static <FROM,TO> Iterator<TO> flatMap(Function<? super FROM,? extends Iterator<TO>> function,
                                             Iterator<FROM> from)
```
  - concat
```
@SafeVarargs
public static <T> Iterator<T> concat(Iterator<? extends T>... iterators)
```
  - concatResourceIterators
```
public static <T> org.neo4j.graphdb.ResourceIterator<T> concatResourceIterators(Iterator<org.neo4j.graphdb.ResourceIterator<T>> iterators)
```
  - concat
```
public static <T> Iterator<T> concat(Iterator<Iterator<T>> iterators)
```
  - asResourceIterable
```
public static <T> org.neo4j.graphdb.ResourceIterable<T> asResourceIterable(org.neo4j.graphdb.ResourceIterator<T> it)
```
  - join
```
public static String join(String joinString,
                          Iterator<?> iter)
```
  - prefetching
```
public static <T> PrefetchingIterator<T> prefetching(Iterator<T> iterator)
```
  - stream
```
public static <T> Stream<T> stream(Iterator<T> iterator)
```
    Create a stream from the given iterator.
    Note: returned stream needs to be closed via BaseStream.close() if the given iterator implements Resource.
    
    Type Parameters:
    
    T - the type of elements in the given iterator
    
    Parameters:
    
    iterator - the iterator to convert to stream
    
    Returns:
    
    stream over the iterator elements
    
    Throws:
    
    NullPointerException - when the given stream is null
  - stream
```
public static <T> Stream<T> stream(Iterator<T> iterator,
                                   int characteristics)
```
    Create a stream from the given iterator with given characteristics.
    Note: returned stream needs to be closed via BaseStream.close() if the given iterator implements Resource.
    
    Type Parameters:
    
    T - the type of elements in the given iterator
    
    Parameters:
    
    iterator - the iterator to convert to stream
    
    characteristics - the logical OR of characteristics for the underlying Spliterator
    
    Returns:
    
    stream over the iterator elements
    
    Throws:
    
    NullPointerException - when the given iterator is null

Class Iterators

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Iterators

Method Detail

firstOrNull

first

lastOrNull

last

singleOrNull

single

fromEnd

fromEndOrNull

iteratorsEqual

single

addToCollection

addToCollectionUnique

addToCollectionUnique

loop

asIterable

count

count

asCollection

asList

asList

asSet

asSet

set

asUniqueSet

asUniqueSet

asIterator

asIterator

asIterator

iterator

iterator

iterator

emptyResourceIterator

contains

asResourceIterator

resourceIterator

array

filter

map

map

asRawIterator

flatMap

concat

concatResourceIterators

concat

asResourceIterable

join

prefetching

stream

stream