com.samskivert.util

Class CollectionUtil

java.lang.Object

com.samskivert.util.CollectionUtil

public class CollectionUtil
extends Object

A collection of collection-related utility functions.

Constructor Summary

Constructors

Constructor and Description
CollectionUtil()

Method Summary

Modifier and Type	Method and Description
static <T,E extends T,C extends Collection<T>> C	addAll(C col, E[] values) Adds all items in the given object array to the supplied collection and returns the supplied collection.
static <T,C extends Collection<T>> C	addAll(C col, Enumeration<? extends T> enm) Adds all items returned by the enumeration to the supplied collection and returns the supplied collection.
static <T,C extends Collection<T>> C	addAll(C col, Iterable<? extends Collection<? extends T>> values) Folds all the specified values into the supplied collection and returns it.
static <T,C extends Collection<T>> C	addAll(C col, Iterator<? extends T> iter) Adds all items returned by the iterator to the supplied collection and returns the supplied collection.
static void	limit(Collection<?> col, int limit) Modify the specified Collection so that only the first limit elements remain, as determined by iteration order.
static <T extends Comparable<? super T>> List<T>	maxList(Iterable<T> iterable) Return a List containing all the elements of the specified Iterable that compare as being equal to the maximum element.
static <T> List<T>	maxList(Iterable<T> iterable, Comparator<? super T> comp) Return a List containing all the elements of the specified Iterable that compare as being equal to the maximum element.
static <T extends Comparable<? super T>> List<T>	minList(Iterable<T> iterable) Return a List containing all the elements of the specified Iterable that compare as being equal to the minimum element.
static <T> List<T>	minList(Iterable<T> iterable, Comparator<? super T> comp) Return a List containing all the elements of the specified Iterable that compare as being equal to the minimum element.
static <K,V,M extends Map<K,V>> M	putAll(M map, Iterable<? extends Map<? extends K,? extends V>> values) Folds all the specified values into the supplied map and returns it.
static <T> List<T>	selectRandomSubset(Collection<T> col, int count) Returns a list containing a random selection of elements from the specified collection.
static <T> T[]	toArray(Collection<? extends T> col, Class<T> type) Returns an Array, of the type specified by the runtime-type token type, containing the elements of the collection.
static int[]	toIntArray(Collection<Integer> col) If a collection contains only Integer objects, it can be passed to this function and converted into an int array.

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionUtil

public CollectionUtil()

Method Detail

addAll

@ReplacedBy(value="com.google.common.collect.Iterators#addAll(Collection, com.google.common.collect.Iterators#forEnumeration(Enumeration))")
public static <T,C extends Collection<T>> C addAll(C col,
                                                                                                                                                                                                Enumeration<? extends T> enm)

Adds all items returned by the enumeration to the supplied collection and returns the supplied collection.

addAll

@ReplacedBy(value="com.google.common.collect.Iterators#addAll()")
public static <T,C extends Collection<T>> C addAll(C col,
                                                                                                                     Iterator<? extends T> iter)

Adds all items returned by the iterator to the supplied collection and returns the supplied collection.

addAll

@ReplacedBy(value="java.util.Collections#addAll()")
public static <T,E extends T,C extends Collection<T>> C addAll(C col,
                                                                                                                   E[] values)

Adds all items in the given object array to the supplied collection and returns the supplied collection. If the supplied array is null, nothing is added to the collection.

addAll

public static <T,C extends Collection<T>> C addAll(C col,
                                                   Iterable<? extends Collection<? extends T>> values)

Folds all the specified values into the supplied collection and returns it.

putAll

public static <K,V,M extends Map<K,V>> M putAll(M map,
                                                Iterable<? extends Map<? extends K,? extends V>> values)

Folds all the specified values into the supplied map and returns it.

limit

public static void limit(Collection<?> col,
                         int limit)

Modify the specified Collection so that only the first limit elements remain, as determined by iteration order. If the Collection is smaller than limit, it is unmodified.

maxList

public static <T extends Comparable<? super T>> List<T> maxList(Iterable<T> iterable)

Return a List containing all the elements of the specified Iterable that compare as being equal to the maximum element.

Throws:

NoSuchElementException - if the Iterable is empty.

maxList

public static <T> List<T> maxList(Iterable<T> iterable,
                                  Comparator<? super T> comp)

Return a List containing all the elements of the specified Iterable that compare as being equal to the maximum element.

Throws:

NoSuchElementException - if the Iterable is empty.

minList

public static <T extends Comparable<? super T>> List<T> minList(Iterable<T> iterable)

Return a List containing all the elements of the specified Iterable that compare as being equal to the minimum element.

Throws:

NoSuchElementException - if the Iterable is empty.

minList

public static <T> List<T> minList(Iterable<T> iterable,
                                  Comparator<? super T> comp)

Return a List containing all the elements of the specified Iterable that compare as being equal to the minimum element.

Throws:

NoSuchElementException - if the Iterable is empty.

selectRandomSubset

public static <T> List<T> selectRandomSubset(Collection<T> col,
                                             int count)

Returns a list containing a random selection of elements from the specified collection. The total number of elements selected will be equal to count, each element in the source collection will be selected with equal probability and no element will be included more than once. The elements in the random subset will always be included in the order they are returned from the source collection's iterator.

Algorithm courtesy of William R. Mahoney, published in Dr. Dobbs Journal, February 2002.

Throws:

IllegalArgumentException - thrown if the size of the collection is smaller than the number of elements requested for the random subset.

toArray

@ReplacedBy(value="com.google.common.collect.Iterables#toArray()")
public static <T> T[] toArray(Collection<? extends T> col,
                                                                                                 Class<T> type)

Returns an Array, of the type specified by the runtime-type token type, containing the elements of the collection.

toIntArray

@ReplacedBy(value="com.google.common.primitives.Ints#toArray()")
public static int[] toIntArray(Collection<Integer> col)

If a collection contains only Integer objects, it can be passed to this function and converted into an int array.

Parameters:

col - the collection to be converted.

Returns:

an int array containing the contents of the collection (in the order returned by the collection's iterator). The size of the array will be equal to the size of the collection.