com.net2plan.utils

Class CollectionUtils

java.lang.Object

com.net2plan.utils.CollectionUtils

public class CollectionUtils
extends Object

Provides extra functionality for the Java Collections Framework. For Java primitives check the corresponding xxxUtils class.

Since:

0.3.0

Author:

Pablo Pavon-Marino, Jose-Luis Izquierdo-Zaragoza

Method Summary

Modifier and Type	Method and Description
static <A> boolean	contains(Collection<A> collection, A value) Checks if an input collection contains a given value.
static <A> boolean	containsAll(Collection<A> container, Collection<A> collection) Checks whether all elements of a collection are present in another one.
static <A> boolean	containsAny(Collection<A> collection1, Collection<A> collection2) Checks whether any element of a collection is present in another one.
static <A extends Number> Map<A,Integer>	convertId2LinearIndexMap(Set<A> elements) Returns a map containing the association of each element with its corresponding position within the set (in linear order).
static <A> Map<A,Integer>	count(Collection<A> collection) Returns a map where each entry represents the number of times that the corresponding key appears in the input collection.
static <A,B> List<A>	find(Map<A,B> map, B value, Constants.SearchType searchType) Returns the key(s) where a given value can be found into a map.
static <A,B> org.apache.commons.collections15.Transformer<A,B>	getMapTransformer(Map<A,B> map) Obtains the equivalent Transformer of a Map.
static <A> Set<A>	intersect(Collection<A>... collections) Returns the intersection set of a series of input collections.
static <A> String	join(Collection<A> collection, String separator) Joins the elements in an input collection using a given separator.
static <A> List<A>	listOf(A... values) Returns a list of the comma-separated input values.
static <A,B> List<B>	select(Map<A,B> map, Collection<A> keys) Returns a list of the values of the selected elements from an input map.
static <A,B> Map<A,B>	selectEntries(Map<A,B> map, Set<A> keys) Returns a map of selected elements from the input map.
static <A> Set<A>	setOf(A... values) Returns a set of the comma-separated input values.
static <A extends Comparable<A>,B extends Comparable<B>> SortedMap<A,B>	sort(Map<A,B> map, Constants.OrderingType orderingType) Returns a SortedMap copy of the input map according to the values.
static <K> SortedMap<K,Double>	toMap(Collection<K> keys, DoubleMatrix1D vals) Given a collection of keys and an array of values, returns a map.

Methods inherited from class java.lang.Object

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

Method Detail

contains

public static <A> boolean contains(Collection<A> collection,
                                   A value)

Checks if an input collection contains a given value.

Type Parameters:

A - Key type

Parameters:

collection - Input collection

value - Value to search

Returns:

true if value is present in collection, and false otherwise. If collection is empty, it will return false

containsAll

public static <A> boolean containsAll(Collection<A> container,
                                      Collection<A> collection)

Checks whether all elements of a collection are present in another one.

Type Parameters:

A - Key type

Parameters:

container - Container collection

collection - Collection with elements to be checked

Returns:

true if all elements in collection are present in container, and false otherwise. If container is empty, it will return false

containsAny

public static <A> boolean containsAny(Collection<A> collection1,
                                      Collection<A> collection2)

Checks whether any element of a collection is present in another one.

Type Parameters:

A - Key type

Parameters:

collection1 - Container collection

collection2 - Collection with elements to be checked

Returns:

true if any element in collection is present in container, and false otherwise. If container is empty, it will return false

convertId2LinearIndexMap

public static <A extends Number> Map<A,Integer> convertId2LinearIndexMap(Set<A> elements)

Returns a map containing the association of each element with its corresponding position within the set (in linear order). First element will be associate to index 0, second element to index 1, and so on.

Important: Since this method is widely used within the tool to deal with conversion between node/link/whatever identifier to its corresponding linear index (first element will be item 0, second element will be item 1, and so on), it is required that in iterator order the elements follow an asceding order.

Type Parameters:

A - Key type

Parameters:

elements - Set of elements in ascending iterator order (null values are not allowed)

Returns:

Element to linear index mapping

count

public static <A> Map<A,Integer> count(Collection<A> collection)

Returns a map where each entry represents the number of times that the corresponding key appears in the input collection.

Type Parameters:

A - Key type

Parameters:

collection - Input collection

Returns:

Map where the key is an item appearing in the input collection, and the value is the number of times that appears

find

public static <A,B> List<A> find(Map<A,B> map,
                                 B value,
                                 Constants.SearchType searchType)

Returns the key(s) where a given value can be found into a map.

Type Parameters:

A - Key type

B - Value type

Parameters:

map - Input map

value - Value to be searched for

searchType - Indicates whether the first, the last, or all occurrences are returned

Returns:

Key(s) in which the given value can be found (in iteration order)

getMapTransformer

public static <A,B> org.apache.commons.collections15.Transformer<A,B> getMapTransformer(Map<A,B> map)

Obtains the equivalent Transformer of a Map.

Type Parameters:

A - Key type

B - Value type

Parameters:

map - Input map

Returns:

Transformer

intersect

public static <A> Set<A> intersect(Collection<A>... collections)

Returns the intersection set of a series of input collections. There is no order guarantee.

Type Parameters:

A - Key type

Parameters:

collections - Series of input collections

Returns:

Intersection set of input collections

join

public static <A> String join(Collection<A> collection,
                              String separator)

Joins the elements in an input collection using a given separator.

Type Parameters:

A - Key type

Parameters:

collection - Input collection

separator - Separator

Returns:

String representation of the input collection

listOf

public static <A> List<A> listOf(A... values)

Returns a list of the comma-separated input values.

Type Parameters:

A - Value type

Parameters:

values - Comma-separated input values

Returns:

List of values (iteration order equal to insertion order)

select

public static <A,B> List<B> select(Map<A,B> map,
                                   Collection<A> keys)

Returns a list of the values of the selected elements from an input map. It is not backed in the input map, thus changes in this list are not reflected in the input map.

Type Parameters:

A - Key type

B - Value type

Parameters:

map - Input map

keys - Keys of the elements to be selected

Returns:

List of the values associated to the input indexes (in iteration order)

selectEntries

public static <A,B> Map<A,B> selectEntries(Map<A,B> map,
                                           Set<A> keys)

Returns a map of selected elements from the input map. It is not backed in the input map, thus changes in the returned one are not reflected in the input map.

Type Parameters:

A - Key type

B - Value type

Parameters:

map - Input map

keys - Keys of the elements to be selected.

Returns:

Map containing the entries corresponding to the keys in the input set (in iteration order)

setOf

public static <A> Set<A> setOf(A... values)

Returns a set of the comma-separated input values.

Type Parameters:

A - Value type

Parameters:

values - Comma-separated input values

Returns:

Set of values (iteration order equal to insertion order)

sort

public static <A extends Comparable<A>,B extends Comparable<B>> SortedMap<A,B> sort(Map<A,B> map,
                                                                                    Constants.OrderingType orderingType)

Returns a SortedMap copy of the input map according to the values.

Type Parameters:

A - Key type

B - Value type

Parameters:

map - Input map

orderingType - Ascending or descending

Returns:

SortedMap. For keys sharing the same value, entries will be ordered according to ascending order of keys.

toMap

public static <K> SortedMap<K,Double> toMap(Collection<K> keys,
                                            DoubleMatrix1D vals)

Given a collection of keys and an array of values, returns a map.

Type Parameters:

K - Key type

Parameters:

keys - Input keys

vals - Input

Returns:

Map containing the entries corresponding to the input keys and values