Package 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

Nested Classes

Modifier and Type	Class	Description
static interface	CollectionUtils.Predicate<T>
static interface	CollectionUtils.Projector<T1,T2>

Constructor Summary

Constructors

Constructor	Description
CollectionUtils()

Method Summary

Modifier and Type	Method	Description
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, T1 extends T> List<T1>	filterByType(Collection<T> c, Class<T1> clazz)
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> List<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 Details

CollectionUtils

public CollectionUtils()

Method Details

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

filterByType

public static <T,
T1 extends T> List<T1> filterByType(Collection<T> c,
 Class<T1> clazz)