de.unkrig.commons.util.collections

Class MapUtil

java.lang.Object

de.unkrig.commons.util.collections.MapUtil

public final class MapUtil
extends Object

Various utility methods for map processing.

Field Summary

Fields

Modifier and Type	Field and Description
static SortedMap	EMPTY_SORTED_MAP Desperately missing from java.util.Collections.

Method Summary

Modifier and Type	Method and Description
static <K,V> Map<K,V>	augment(Map<K,V> delegate, K extraKey, V extraValue) Returns a Map that is composed of the delegate and one extra entry.
static <K,V> Map<K,V>	combine(Map<K,V> map1, Map<? extends K,? extends V> map2) Returns a Map that is composed of map1 and map2, where map1 takes precedence over <map2.
static <K,V> SortedMap<K,V>	emptySortedMap() Desperately missing from java.util.Collections.
static <K,V> Map.Entry<K,V>	entry(K key, V initialValue)
static boolean	equal(Object o1, Object o2) Deprecated. Moved to ObjectUtil.equals(Object, Object)
static <K,V> Map<K,V>	fromMappings(Object... keysAndValues) Deprecated. Use map(Object...) instead
static <K,V> HashMap<K,V>	hashMapOf(int initialCapacity, Map.Entry<? extends K,? extends V>... entries)
static <K,V> HashMap<K,V>	hashMapOf(Map.Entry<? extends K,? extends V>... entries) Creates, fills and returns a HashMap.
static <K,V> Map<K,V>	map(K[] keys, V[] values) Returns an unmodifiable map, mapping the given key-value pairs.
static <K,V> Map<K,V>	map(Object... keyValuePairs) Returns an unmodifiable map, mapping the given key-value pairs.
static <K,V> Map<K,V>	override(Map<K,V> delegate, K extraKey, V extraValue) Returns a Map that is composed of the delegate and one extra entry.
static <K,V,M extends Map<K,V>> M	putAll(M subject, boolean allowDuplicateKeys, Map.Entry<? extends K,? extends V>... entries) Puts all entries into the subject.
static <K,V,M extends Map<K,V>> M	putAll(M subject, Map.Entry<? extends K,? extends V>... entries) Puts all entries into the subject.
static <K,V> TreeMap<K,V>	treeMapOf(Map.Entry<? extends K,? extends V>... entries)

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 SortedMap EMPTY_SORTED_MAP

Desperately missing from java.util.Collections.

Method Detail

map

public static <K,V> Map<K,V> map(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:

ArrayIndexOutOfBoundsException - The length of keyValuePairs is odd

IllegalArgumentException - Two of the keys are equal

map

public static <K,V> 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:

ArrayIndexOutOfBoundsException - The length of keyValuePairs is odd

IllegalArgumentException - Two of the keys are equal

hashMapOf

public static <K,V> HashMap<K,V> hashMapOf(Map.Entry<? extends K,? extends V>... entries)

Creates, fills and returns a HashMap. The initial capacity of the HashMap is chosen to be optimal for the number of entries.

Returns:

A HashMap containing all entries/

Throws:

IllegalArgumentException - Two entries have equal keys

hashMapOf

public static <K,V> HashMap<K,V> hashMapOf(int initialCapacity,
                                           Map.Entry<? extends K,? extends V>... entries)

Parameters:

initialCapacity - See the documentation of HashMap

Returns:

A HashMap containing all entries/

Throws:

IllegalArgumentException - Two entries have equal keys

treeMapOf

public static <K,V> TreeMap<K,V> treeMapOf(Map.Entry<? extends K,? extends V>... entries)

Returns:

A TreeMap containing all entries/

Throws:

IllegalArgumentException - Two entries have equal keys

putAll

public static <K,V,M extends Map<K,V>> M putAll(M subject,
                                                Map.Entry<? extends K,? extends V>... entries)

Puts all entries into the subject.

Returns:

The subject

Throws:

IllegalArgumentException - Two entries have equal keys

putAll

public static <K,V,M extends Map<K,V>> M putAll(M subject,
                                                boolean allowDuplicateKeys,
                                                Map.Entry<? extends K,? extends V>... entries)

Puts all entries into the subject.

Returns:

The subject

Throws:

IllegalArgumentException - Two entries have equal keys, and allowDuplicateKeys is false

entry

public static <K,V> Map.Entry<K,V> entry(K key,
                                         V initialValue)

Returns:

A Map.Entry with the given key and the initialValue

See Also:

Map.Entry.setValue(Object)

emptySortedMap

public static <K,V> SortedMap<K,V> emptySortedMap()

Desperately missing from java.util.Collections.

combine

public static <K,V> Map<K,V> combine(Map<K,V> map1,
                                     Map<? extends K,? extends V> map2)

Returns a Map that is composed of map1 and map2, where map1 takes precedence over <map2.

All modifying operations are directed to map1; map2 is never modified.

augment

public static <K,V> Map<K,V> augment(Map<K,V> delegate,
                                     K extraKey,
                                     V extraValue)

Returns a Map that is composed of the delegate and one extra entry. If the delegate contains the extraKey, then the value from the delegate takes precedence.

override

public static <K,V> Map<K,V> override(Map<K,V> delegate,
                                      K extraKey,
                                      V extraValue)

Returns a Map that is composed of the delegate and one extra entry. If the delegate contains the extraKey, then the extraValue takes precedence.

equal

@Deprecated
public static boolean equal(@Nullable
                                         Object o1,
                                         @Nullable
                                         Object o2)

Deprecated. Moved to ObjectUtil.equals(Object, Object)

fromMappings

@Deprecated
public static <K,V> Map<K,V> fromMappings(Object... keysAndValues)

Deprecated. Use map(Object...) instead