com.alibaba.nacos.client.naming.utils

类 CollectionUtils

java.lang.Object

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

public class CollectionUtils
extends Object

Provides utility methods and decorators for Collection instances.

从以下版本开始:

Commons Collections 1.0

版本:

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

作者:

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

构造器概要

构造器

构造器和说明
CollectionUtils() CollectionUtils should not normally be instantiated.

方法概要

限定符和类型	方法和说明
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.

从类继承的方法 java.lang.Object

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

构造器详细资料

CollectionUtils

public CollectionUtils()

CollectionUtils should not normally be instantiated.

方法详细资料

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.

参数:

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

b - the collection to subtract, must not be null

返回:

a new collection with the results

另请参阅:

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.

参数:

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

返回:

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.

参数:

a - the first collection, must not be null

b - the second collection, must not be null

返回:

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.

参数:

coll - the collection to check, may be null

返回:

true if empty or null

从以下版本开始:

Commons Collections 3.2