de.larssh.utils.collection

Class Iterators

java.lang.Object

de.larssh.utils.collection.Iterators

public final class Iterators
extends Object

This class contains helper methods for Iterator.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Iterators.ElementsSupplierStateHandler<E> An instance of this is passed to the elements supplier at the time of calculating the next element.

Method Summary

Modifier and Type	Method and Description
static <E> PeekableIterator<E>	iterator(Function<Iterators.ElementsSupplierStateHandler<E>,E> elementsSupplier) Wraps elementsSupplier into a PeekableIterator.
static <E> PeekableIterator<E>	peekableIterator(Iterator<E> iterator) Wraps iterator into a PeekableIterator.
static <E> Stream<E>	stream(Function<Iterators.ElementsSupplierStateHandler<E>,E> elementsSupplier) Returns a sequential Stream with the elementsSupplier as its source.
static <E> Stream<E>	stream(Iterator<E> iterator) Returns a sequential Stream with the iterator as its source.

Methods inherited from class java.lang.Object

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

Method Detail

iterator

public static <E> PeekableIterator<E> iterator(Function<Iterators.ElementsSupplierStateHandler<E>,E> elementsSupplier)

Wraps elementsSupplier into a PeekableIterator. This is probably the simplest way of writing an iterator.

Note: This iterator is not thread safe.

Usage example: The following shows how to create an iterator returning every second element only.

 Iterator<E> oldIterator = ...;
 Iterator<E> newIterator = Iterators.iterator(state -> {
     if (!oldIterator.hasNext() && !oldIterator.hasNext()) {
         return state.endOfData();
     }
     return oldIterator.next();
 });
 

Type Parameters:

E - the type of the iterator elements

Parameters:

elementsSupplier - the elements supplier with the state as parameter

Returns:

a PeekableIterator wrapping elementsSupplier

peekableIterator

public static <E> PeekableIterator<E> peekableIterator(Iterator<E> iterator)

Wraps iterator into a PeekableIterator.

Note: The resulting iterator is not thread safe.

Type Parameters:

E - the type of the iterator elements

Parameters:

iterator - the iterator

Returns:

a PeekableIterator wrapping iterator

stream

public static <E> Stream<E> stream(Function<Iterators.ElementsSupplierStateHandler<E>,E> elementsSupplier)

Returns a sequential Stream with the elementsSupplier as its source.

Check out iterator(Function) for more information about elementsSupplier.

Type Parameters:

E - the type of the iterator elements

Parameters:

elementsSupplier - the elements supplier with the state as parameter

Returns:

a Stream with the elements of elementsSupplier

stream

public static <E> Stream<E> stream(Iterator<E> iterator)

Returns a sequential Stream with the iterator as its source.

Type Parameters:

E - the type of the iterator elements

Parameters:

iterator - the iterator

Returns:

a Stream with the elements of iterator