xades4j.utils
Class CollectionUtils

java.lang.Object
  xades4j.utils.CollectionUtils

public class CollectionUtils
extends Object

Provides some utility methods over collections.

Author:

Luís

Nested Class Summary

static interface	CollectionUtils.Predicate<T>
static interface	CollectionUtils.Projector<T1,T2>

Constructor Summary

CollectionUtils()

Method Summary

static <T> Collection<T>	cloneOrEmptyIfNull(Collection<T> c)
static <TK,TV> Map<TK,TV>	cloneOrEmptyIfNull(Map<TK,TV> m)
static <T> Collection<T>	emptyIfNull(Collection<T> c) Get an empty collection if the given collection is null.
static <TK,TV> Map<TK,TV>	emptyIfNull(Map<TK,TV> m)
static <T> List<T>	filter(Collection<T> c, CollectionUtils.Predicate<T> p)
static <T> Collection<T>	newIfNull(Collection<T> c, int size) Get a collection with the specified initial size if the given collection is null.
static <TK,TV> Map<TK,TV>	newIfNull(Map<TK,TV> m, int size) Same as newIfNull but for maps.
static <T> boolean	nullOrEmpty(Collection<T> c) Indicates whether a collection is null or empty.
static <TSrc,TDest> Collection<TDest>	project(Collection<TSrc> c, CollectionUtils.Projector<TSrc,TDest> p)

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionUtils

public CollectionUtils()

Method Detail

newIfNull

public static <T> Collection<T> newIfNull(Collection<T> c,
                                          int size)

Get a collection with the specified initial size if the given collection is null. The returned collection, if new, will support the remove operation.

Parameters:

c - the collection to be tested

size - the initial size of the returned collection, if new

Returns:

a new collection or c if it is not null

newIfNull

public static <TK,TV> Map<TK,TV> newIfNull(Map<TK,TV> m,
                                           int size)

Same as newIfNull but for maps.

Parameters:

m - the map to be tested

size - the initial size of the returned map, if new

Returns:

a new map or m if it is not null

emptyIfNull

public static <T> Collection<T> emptyIfNull(Collection<T> c)

Get an empty collection if the given collection is null. The returned collection, if new, is immutable.

Parameters:

c - the collection to be tested

Returns:

a new empty collection or c if it is not null

emptyIfNull

public static <TK,TV> Map<TK,TV> emptyIfNull(Map<TK,TV> m)

cloneOrEmptyIfNull

public static <T> Collection<T> cloneOrEmptyIfNull(Collection<T> c)

cloneOrEmptyIfNull

public static <TK,TV> Map<TK,TV> cloneOrEmptyIfNull(Map<TK,TV> m)

nullOrEmpty

public static <T> boolean nullOrEmpty(Collection<T> c)

Indicates whether a collection is null or empty.

Parameters:

c - the collection to be tested

Returns:

true if the collection is null or empty

filter

public static <T> List<T> filter(Collection<T> c,
                                 CollectionUtils.Predicate<T> p)

project

public static <TSrc,TDest> Collection<TDest> project(Collection<TSrc> c,
                                                     CollectionUtils.Projector<TSrc,TDest> p)