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

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

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.

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.