de.unkrig.commons.util.collections

Class IterableUtil

java.lang.Object

de.unkrig.commons.util.collections.IterableUtil

public final class IterableUtil
extends Object

Various Iterable-related utility methods.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	IterableUtil.ElementWithContext<T> Deprecated. Use ElementWithContext instead

Field Summary

Fields

Modifier and Type	Field and Description
static Iterable<Integer>	NATURALS Produces the sequence 1, 2, 3, ...
static Iterable<Integer>	NATURALS0 Produces the sequence 0, 1, 2, ...

Method Summary

Modifier and Type	Method and Description
static <T> void	addAllElementsTo(Iterable<T> iterable, Collection<? super T> target) Adds all elements of the iterable to the target collection.
static <T> Collection<T>	asCollection(Iterable<T> delegate) Wraps the given Iterable in a collection.
static <T> Iterable<T>	concat(Iterable<? extends Iterable<? extends T>> elements)
static <T> Iterable<T>	concat(Iterable<? extends T> element1, Iterable<? extends T> element2)
static <T> Iterable<T>	concat(Iterable<? extends T> element1, Iterable<? extends T> element2, Iterable<? extends T> element3)
static <T> Iterable<T>	concat(Iterable<? extends T> element1, Iterable<? extends T> element2, Iterable<? extends T> element3, Iterable<? extends T> element4)
static <T> Iterable<T>	concat(Iterable<? extends T> element1, T... element2)
static <T> Iterable<T>	concat(T element1, Iterable<? extends T> element2)
static <T> Iterable<T>	concat(T element1, T element2, Iterable<? extends T> element3)
static <T> Iterable<T>	filter(Iterable<? extends T> delegate, Predicate<? super T> qualifies) Returns an Iterable which hides the elements of the delegate which do not qualifiy.
static Iterable<Integer>	foR(int start, int end) Equivalent with foR(start, end,1).
static Iterable<Integer>	foR(int start, int end, int step) Returns a sequence of integers which reach from start (inclusively) to end (exclusively), with a step increment.
static <T> Iterable<ElementWithContext<T>>	iterableWithContext(Iterable<? extends T> delegate) Wraps the delegate iterable in an Iterable<ElementWithContext>.
static <T> Iterator<ElementWithContext<T>>	iteratorWithContext(Iterator<? extends T> delegate) Deprecated. Use IteratorUtil.iteratorWithContext(Iterator) instead
static <T> Iterable<T>	repeat(T subject, int n)
static <E> Iterable<E>	reverseList(List<E> list)
static <I,O> Iterable<O>	transform(Iterable<? extends I> delegate, Transformer<? super I,? extends O> transform) Returns an iterable which contains the transformed elements of the delegate
static <T> Iterable<T>	unmodifiableIterable(Iterable<? extends T> i)

Methods inherited from class java.lang.Object

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

Field Detail

NATURALS

public static final Iterable<Integer> NATURALS

Produces the sequence 1, 2, 3, ... Integer.MAX_VALUE

NATURALS0

public static final Iterable<Integer> NATURALS0

Produces the sequence 0, 1, 2, ... Integer.MAX_VALUE

Method Detail

unmodifiableIterable

public static <T> Iterable<T> unmodifiableIterable(Iterable<? extends T> i)

Returns:

An Iterable which can't be modified through the Iterator.remove() method

repeat

public static <T> Iterable<T> repeat(T subject,
                                     int n)

Returns:

An Iterable producing the given subject n times

reverseList

public static <E> Iterable<E> reverseList(List<E> list)

Returns:

An Iterable that traverses the elements of the given List in reverse order, starting with the last element of the list

concat

public static <T> Iterable<T> concat(T element1,
                                     Iterable<? extends T> element2)

Returns:

An iterator for element1 and the elements of element2

concat

public static <T> Iterable<T> concat(T element1,
                                     T element2,
                                     Iterable<? extends T> element3)

Returns:

An iterator for element1 element2 and the elements of element3

concat

public static <T> Iterable<T> concat(Iterable<? extends T> element1,
                                     T... element2)

Returns:

An iterator for the elements of element1 and element2

concat

public static <T> Iterable<T> concat(Iterable<? extends T> element1,
                                     Iterable<? extends T> element2)

Returns:

An iterator for the elements of element1 and element2

concat

public static <T> Iterable<T> concat(Iterable<? extends T> element1,
                                     Iterable<? extends T> element2,
                                     Iterable<? extends T> element3)

Returns:

An iterator for the elements of element1, element2 and element3

concat

public static <T> Iterable<T> concat(Iterable<? extends T> element1,
                                     Iterable<? extends T> element2,
                                     Iterable<? extends T> element3,
                                     Iterable<? extends T> element4)

Returns:

An iterator for the elements of element1, element2, element3 and element4

concat

public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> elements)

Returns:

An iterator for the elements of the given elements

filter

public static <T> Iterable<T> filter(Iterable<? extends T> delegate,
                                     Predicate<? super T> qualifies)

Returns an Iterable which hides the elements of the delegate which do not qualifiy.

transform

public static <I,O> Iterable<O> transform(Iterable<? extends I> delegate,
                                          Transformer<? super I,? extends O> transform)

Returns an iterable which contains the transformed elements of the delegate

asCollection

public static <T> Collection<T> asCollection(Iterable<T> delegate)

Wraps the given Iterable in a collection. As enforced by the nature of the Iterable, the only supported modifying operation of the returned collection is element removal.

See Also:

Collection.remove(Object), Collection.removeAll(Collection), Collection.retainAll(Collection), Collection.clear()

iterableWithContext

public static <T> Iterable<ElementWithContext<T>> iterableWithContext(Iterable<? extends T> delegate)

Wraps the delegate iterable in an Iterable<ElementWithContext>.

See Also:

IterableUtil.ElementWithContext, IteratorUtil.iteratorWithContext(Iterator)

iteratorWithContext

@Deprecated
public static <T> Iterator<ElementWithContext<T>> iteratorWithContext(Iterator<? extends T> delegate)

Deprecated. Use IteratorUtil.iteratorWithContext(Iterator) instead

foR

public static Iterable<Integer> foR(int start,
                                    int end)

Equivalent with foR(start, end,1).

See Also:

foR(int, int, int)

foR

public static Iterable<Integer> foR(int start,
                                    int end,
                                    int step)

Returns a sequence of integers which reach from start (inclusively) to end (exclusively), with a step increment.

More precise: Iff step is greater than zero, then the sequence is start, start + step, and so forth, and ends with the last value which is less than end.

Otherwise, iff step is less than zero, then the sequence is start, start + step, and so forth, and ends with the last value which is greater than end.

Otherwise, step is zero, and the returned sequence is either an infinite sequence of values start, or, iff start == end, an empty sequence.

Throws:

IllegalArgumentException - step > 0 && end < start

IllegalArgumentException - step < 0 && end > start

addAllElementsTo

public static <T> void addAllElementsTo(Iterable<T> iterable,
                                        Collection<? super T> target)

Adds all elements of the iterable to the target collection.