org.arp.javautil.collections

Class Collections

java.lang.Object

org.arp.javautil.collections.Collections

public class Collections
extends Object

Extra utilities for collections.

Author:

Andrew Post

Method Summary

Modifier and Type	Method and Description
static <K> boolean	containsAny(Set<K> aSet, K[] arr) Checks whether any of an array's elements are also in the provided set.
static <K> Set<K>	intersection(Collection<Set<K>> sets)
static <K> Set<K>	intersection(Set<K>... sets)
static <K,V> HashMap<K,V>	newHashMap(int expectedCapacity)
static <K,V> void	putList(Map<K,List<V>> map, K key, V valueElt) Puts a value into a map of key -> list of values.
static <K,V> void	putListMult(Map<K,List<V>> map, K key, Collection<? extends V> values) Puts a collection of values into a map of key -> list of values.
static <K,V> void	putSet(Map<K,Set<V>> map, K key, V valueElt) Puts a value into a map of key -> set of values.
static <K,V> void	putSetAll(Map<K,Set<V>> map, Map<K,Set<V>> other) Copies all of the mappings from the second map to the first.
static <K,V> void	putSetMult(Map<K,Set<V>> map, K key, Collection<? extends V> values) Puts a collection of values into a map of key -> set of values.

Methods inherited from class java.lang.Object

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

Method Detail

putList

public static <K,V> void putList(Map<K,List<V>> map,
                                 K key,
                                 V valueElt)

Puts a value into a map of key -> list of values. If the specified key is new, it creates an ArrayList as its value.

Parameters:

map - a Map.

key - a key.

valueElt - a value.

putListMult

public static <K,V> void putListMult(Map<K,List<V>> map,
                                     K key,
                                     Collection<? extends V> values)

Puts a collection of values into a map of key -> list of values. If the specified key is new, it creates an ArrayList as its value.

Parameters:

map - a Map.

key - a key.

values - a Collection of values.

putSet

public static <K,V> void putSet(Map<K,Set<V>> map,
                                K key,
                                V valueElt)

Puts a value into a map of key -> set of values. If the specified key is new, it creates a HashSet as its value.

Parameters:

map - a Map.

key - a key.

valueElt - a value.

putSetMult

public static <K,V> void putSetMult(Map<K,Set<V>> map,
                                    K key,
                                    Collection<? extends V> values)

Puts a collection of values into a map of key -> set of values. If the specified key is new, it creates an ArrayList as its value.

Parameters:

map - a Map.

key - a key.

values - a Collection of values.

putSetAll

public static <K,V> void putSetAll(Map<K,Set<V>> map,
                                   Map<K,Set<V>> other)

Copies all of the mappings from the second map to the first. The value for each key is the union of the first and second maps' values for that key.

Type Parameters:

K -

V -

Parameters:

map - the first Map.

other - the second Map.

containsAny

public static <K> boolean containsAny(Set<K> aSet,
                                      K[] arr)

Checks whether any of an array's elements are also in the provided set.

Parameters:

aSet - a Set.

arr - an array.

Returns:

true or false.

intersection

public static <K> Set<K> intersection(Collection<Set<K>> sets)

intersection

@SafeVarargs
public static <K> Set<K> intersection(Set<K>... sets)

newHashMap

public static <K,V> HashMap<K,V> newHashMap(int expectedCapacity)