org.alfresco.po.common.util

Class RMCollectionUtils

java.lang.Object

org.alfresco.po.common.util.RMCollectionUtils

public final class RMCollectionUtils
extends Object

Various common helper methods for Collections. This class is probably only appropriate for use with relatively small collections as it has not been optimised for dealing with large collections.

Since:

2.4.a

Author:

Neil Mc Erlean

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RMCollectionUtils.Difference This enum represents a change in an entry between 2 collections.

Method Summary

Modifier and Type	Method and Description
static <K,V> RMCollectionUtils.Difference	diffKey(Map<K,V> from, Map<K,V> to, K key) Determines the change in a Map entry between two Maps.
static <T> T	head(List<T> l) Returns the head (element at index 0) of the provided List.
static <T> List<T>	tail(List<T> l) Returns the tail of the provided List i.e. the sublist which contains all elements of the given list except the head.

Methods inherited from class java.lang.Object

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

Method Detail

head

public static <T> T head(List<T> l)

Returns the head (element at index 0) of the provided List.

Type Parameters:

T - the type of the List.

Parameters:

l - the list whose head is sought.

Returns:

the head element or null for the empty list.

Throws:

NullPointerException - if l is null

tail

public static <T> List<T> tail(List<T> l)

Returns the tail of the provided List i.e. the sublist which contains all elements of the given list except the head.

Type Parameters:

T - the type of the List.

Parameters:

l - the list whose tail is sought.

Returns:

the tail sublist, which will be an empty list if the provided list had only a single element.

Throws:

NullPointerException - if l is null

UnsupportedOperationException - if the provided list was empty.

diffKey

public static <K,V> RMCollectionUtils.Difference diffKey(Map<K,V> from,
                                                         Map<K,V> to,
                                                         K key)

Determines the change in a Map entry between two Maps. Note that both maps must have the same types of key-value pair.

Type Parameters:

K - the type of the key.

V - the type of the value.

Parameters:

from - the first collection.

to - the second collection.

key - the key identifying the entry.

Returns:

the RMCollectionUtils.Difference.

Throws:

IllegalArgumentException - if key is null.