org.jtheque.utils.collections
Class CollectionUtils

java.lang.Object
  org.jtheque.utils.collections.CollectionUtils

public final class CollectionUtils
extends Object

Provide some utilities operations on collections.

Author:

Baptiste Wicht

Method Summary

static <T> List<T>	copyOf(Collection<T> list) Return a copy of the list.
static <T> List<T>	emptyList() Return an empty list.
static <S,T> Collection<T>	expand(Collection<S> collection, Expander<S,T> expander) Return a collection expanded.
static <T> void	filter(Collection<T> collection, Filter<T> filter) Filter a collection with a filter.
static <T> T	first(Iterable<T> collection) Return the first element of the collection.
static <T> void	forAllDo(Iterable<T> collection, Closure<T> closure) Perform a closure on all the objects of the collection.
static <T> void	goToFirst(ListIterator<T> iterator) Move the iterator to the first element.
static <T> void	goToLast(Iterator<T> iterator) Move the iterator to the last element.
static void	reverse(List<?> list) Reverse a list.
static <T,K> void	reverse(Map<T,K> map) Reverse the order of a map.
static <T> void	sort(List<T> list, Comparator<T> comparator) Sort a list.
static <T> Collection<T>	toCollection(Enumeration<T> enumeration) Convert the enumeration to a collection.

Methods inherited from class java.lang.Object

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

Method Detail

forAllDo

public static <T> void forAllDo(Iterable<T> collection,
                                Closure<T> closure)

Perform a closure on all the objects of the collection.

Parameters:

collection - The collection of the objects.

closure - The closure.

copyOf

public static <T> List<T> copyOf(Collection<T> list)

Return a copy of the list.

Type Parameters:

T - The type contained in the list.

Parameters:

list - The List to copy.

Returns:

A copy of the list.

expand

public static <S,T> Collection<T> expand(Collection<S> collection,
                                         Expander<S,T> expander)

Return a collection expanded.

Type Parameters:

T - The type of object in the collection.

Parameters:

collection - The collection to expand.

expander - The expander object.

Returns:

The expanded collection.

filter

public static <T> void filter(Collection<T> collection,
                              Filter<T> filter)

Filter a collection with a filter.

Type Parameters:

T - The type of object in the collection.

Parameters:

collection - The collection to filter.

filter - The filter.

reverse

public static <T,K> void reverse(Map<T,K> map)

Reverse the order of a map. This method provide correct result only for map who retain the insertion order.

Type Parameters:

T - The Key type.

K - The value type.

Parameters:

map - The map to reverse.

reverse

public static void reverse(List<?> list)

Reverse a list.

Parameters:

list - The list to reverse.

sort

public static <T> void sort(List<T> list,
                            Comparator<T> comparator)

Sort a list.

Type Parameters:

T - The type of object in the collection.

Parameters:

list - The list to sort.

comparator - The comparator to use to sort the list.

emptyList

public static <T> List<T> emptyList()

Return an empty list. This list is unmodifiable.

Type Parameters:

T - The Type of object to store in the list.

Returns:

The empty list.

goToFirst

public static <T> void goToFirst(ListIterator<T> iterator)

Move the iterator to the first element.

Type Parameters:

T - The type of object stored in the iterator.

Parameters:

iterator - The list iterator.

goToLast

public static <T> void goToLast(Iterator<T> iterator)

Move the iterator to the last element.

Type Parameters:

T - The type of object stored in the iterator.

Parameters:

iterator - The iterator.

toCollection

public static <T> Collection<T> toCollection(Enumeration<T> enumeration)

Convert the enumeration to a collection.

Type Parameters:

T - The type of object stored in the enumeration.

Parameters:

enumeration - The enumeration to convert to Collection.

Returns:

A Collection containing all the elements of the enumeration.

first

public static <T> T first(Iterable<T> collection)

Return the first element of the collection.

Type Parameters:

T - The objects stored in the collection.

Parameters:

collection - The collection.

Returns:

The first element of the collection or null if the collection is empty.