public class

CollectionUtils

extends Object
java.lang.Object
   ↳ xades4j.utils.CollectionUtils

Class Overview

Provides some utility methods over collections.

Summary

Nested Classes
interface CollectionUtils.Predicate<T>  
interface CollectionUtils.Projector<T1, T2>  
Public Constructors
CollectionUtils()
Public Methods
static <T> Collection<T> cloneOrEmptyIfNull(Collection<T> c)
static <TK, TV> Map<TK, TV> cloneOrEmptyIfNull(Map<TK, TV> m)
static <TK, TV> Map<TK, TV> emptyIfNull(Map<TK, TV> m)
static <T> Collection<T> emptyIfNull(Collection<T> c)
Get an empty collection if the given collection is null.
static <T> List<T> filter(Collection<T> c, 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, Projector<TSrc, TDest> p)
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public CollectionUtils ()

Public Methods

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

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

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

public static 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

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

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

public static 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

public static 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

public static 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

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