de.unkrig.commons.util.collections

Class CollectionUtil

java.lang.Object

de.unkrig.commons.util.collections.CollectionUtil

public final class CollectionUtil
extends java.lang.Object

java.util.collection-related utility methods.

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.Iterator	AT_END An iterator which is at its end.
static java.util.SortedMap	EMPTY_SORTED_MAP Desperately missing from java.util.Collections.
static java.util.SortedSet	EMPTY_SORTED_SET Desperately missing from java.util.Collections.

Method Summary

Modifier and Type	Method and Description
static <K,V> java.util.SortedMap<K,V>	emptySortedMap() Desperately missing from java.util.Collections.
static <T> java.util.SortedSet<T>	emptySortedSet() Desperately missing from java.util.Collections.
static <K,V> java.util.Map<K,V>	map(K[] keys, V[] values) Returns an unmodifiable map, mapping the given key-value pairs.
static <K,V> java.util.Map<K,V>	map(java.lang.Object... keyValuePairs) Returns an unmodifiable map, mapping the given key-value pairs.
static <T> T	removeFirstFrom(java.util.Collection<T> subject) Removes and returns the first element of the given collection.
static <T> java.util.Collection<T>	sorted(java.util.Collection<T> collection) Returns an unmodifiable collection containing the elements of the given collection, but sorted by their "natural ordering".

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_SORTED_MAP

public static final java.util.SortedMap EMPTY_SORTED_MAP

Desperately missing from java.util.Collections.

EMPTY_SORTED_SET

public static final java.util.SortedSet EMPTY_SORTED_SET

Desperately missing from java.util.Collections.

AT_END

public static final java.util.Iterator AT_END

An iterator which is at its end.

Method Detail

removeFirstFrom

@Nullable
public static <T> T removeFirstFrom(java.util.Collection<T> subject)

Removes and returns the first element of the given collection. This is also known as the 'shift' operation.

Returns:

null iff the collection is empty

map

public static <K,V> java.util.Map<K,V> map(java.lang.Object... keyValuePairs)

Returns an unmodifiable map, mapping the given key-value pairs. null keys and null values are supported.

Parameters:

keyValuePairs - An alternating sequence of keys and values

Throws:

java.lang.ArrayIndexOutOfBoundsException - The length of keyValuePairs is odd

java.lang.IllegalArgumentException - Two of the keys are equal

map

public static <K,V> java.util.Map<K,V> map(K[] keys,
                                           V[] values)

Returns an unmodifiable map, mapping the given key-value pairs. null keys and null values are supported.

Throws:

java.lang.ArrayIndexOutOfBoundsException - The length of keyValuePairs is odd

java.lang.IllegalArgumentException - Two of the keys are equal

emptySortedMap

public static <K,V> java.util.SortedMap<K,V> emptySortedMap()

Desperately missing from java.util.Collections.

emptySortedSet

public static <T> java.util.SortedSet<T> emptySortedSet()

Desperately missing from java.util.Collections.

sorted

public static <T> java.util.Collection<T> sorted(java.util.Collection<T> collection)

Returns an unmodifiable collection containing the elements of the given collection, but sorted by their "natural ordering".