com.alibaba.nacos.client.naming.utils

Class CollectionUtils

java.lang.Object

com.alibaba.nacos.client.naming.utils.CollectionUtils

public class CollectionUtils
extends Object

Provides utility methods and decorators for Collection instances.

Since:

Commons Collections 1.0

Version:

$Revision: 1713167 $ $Date: 2015-11-07 20:44:03 +0100 (Sat, 07 Nov 2015) $

Author:

Rodney Waldhoff, Paul Jack, Stephen Colebourne, Steve Downey, Herve Quiroz, Peter KoBek, Matthew Hawthorne, Janek Bogucki, Phil Steitz, Steven Melzer, Jon Schewe, Neil O'Toole, Stephen Smith

Constructor Summary

Constructors

Constructor and Description
CollectionUtils() CollectionUtils should not normally be instantiated.

Method Summary

Modifier and Type	Method and Description
static Map	getCardinalityMap(Collection coll) Returns a Map mapping each unique element in the given Collection to an Integer representing the number of occurrences of that element in the Collection.
static boolean	isEmpty(Collection coll) Null-safe check if the specified collection is empty.
static boolean	isEqualCollection(Collection a, Collection b) Returns true iff the given Collections contain exactly the same elements with exactly the same cardinalities.
static Collection	subtract(Collection a, Collection b) Returns a new Collection containing a - b.

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionUtils

public CollectionUtils()

CollectionUtils should not normally be instantiated.

Method Detail

subtract

public static Collection subtract(Collection a,
                                  Collection b)

Returns a new Collection containing a - b. The cardinality of each element e in the returned Collection will be the cardinality of e in a minus the cardinality of e in b, or zero, whichever is greater.

Parameters:

a - the collection to subtract from, must not be null

b - the collection to subtract, must not be null

Returns:

a new collection with the results

See Also:

Collection.removeAll(java.util.Collection<?>)

getCardinalityMap

public static Map getCardinalityMap(Collection coll)

Returns a Map mapping each unique element in the given Collection to an Integer representing the number of occurrences of that element in the Collection.

Only those elements present in the collection will appear as keys in the map.

Parameters:

coll - the collection to get the cardinality map for, must not be null

Returns:

the populated cardinality map

isEqualCollection

public static boolean isEqualCollection(Collection a,
                                        Collection b)

Returns true iff the given Collections contain exactly the same elements with exactly the same cardinalities.

That is, iff the cardinality of e in a is equal to the cardinality of e in b, for each element e in a or b.

Parameters:

a - the first collection, must not be null

b - the second collection, must not be null

Returns:

true iff the collections contain the same elements with the same cardinalities.

isEmpty

public static boolean isEmpty(Collection coll)

Null-safe check if the specified collection is empty.

Null returns true.

Parameters:

coll - the collection to check, may be null

Returns:

true if empty or null

Since:

Commons Collections 3.2