Module com.aoapps.collections

Package com.aoapps.collections

Class MinimalMap

java.lang.Object

com.aoapps.collections.MinimalMap

public final class MinimalMap
extends Object

MinimalMap provides a set of static methods to dynamically choose the most efficient Map implementation. The implementation of Map is changed as needed. MinimalMap is most suited for building map-based data structures that use less heap space than a pure HashMap-based solution.

Insertion order is maintained.

size=0: Collections.emptyMap()
size=1: Collections.singletonMap(java.lang.Object, java.lang.Object)
size=2: LinkedHashMap

Author:

AO Industries, Inc.

Method Summary

Modifier and Type	Method	Description
static <K, V> boolean	containsKey(Map<K,V> map, K key)	Deprecated. Since empty maps are no longer represented by null, invoke Map.containsKey(java.lang.Object) directly now.
static <K, V> Map<K,V>	copy(Map<K,V> map)	Performs a shallow copy of a map.
static <K, V> Map<K,V>	emptyMap()	Gets the empty map representation.
static <K, V> V	get(Map<K,V> map, K key)	Deprecated. Since empty maps are no longer represented by null, invoke Map.get(java.lang.Object) directly now.
static <K, V> Map<K,V>	put(Map<K,V> map, K key, V value)	Puts a new element in a map, returning the (possibly new) map.
static <K, V> Map<K,V>	remove(Map<K,V> map, K key)	Removes an element from a map, returning the (possibly new) map.
static <K, V> Map<K,V>	unmodifiable(Map<K,V> map)	Gets an unmodifiable wrapper around this map.
static <K, V> Collection<V>	values(Map<K,V> map)	Deprecated. Since empty maps are no longer represented by null, invoke Map.values() directly now.
static <K, V> Collection<V>	valuesCopy(Map<K,V> map)	Performs a shallow copy of the value collection.

Methods inherited from class java.lang.Object

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

Method Details

emptyMap

public static <K,
V> Map<K,V> emptyMap()

Gets the empty map representation.

put

public static <K,
V> Map<K,V> put(Map<K,V> map,
 K key,
 V value)

Puts a new element in a map, returning the (possibly new) map.

remove

public static <K,
V> Map<K,V> remove(Map<K,V> map,
 K key)

Removes an element from a map, returning the (possibly new) map.

get

@Deprecated
public static <K,
V> V get(Map<K,V> map,
 K key)

Deprecated.

Since empty maps are no longer represented by null, invoke Map.get(java.lang.Object) directly now.

Gets an element from a map.

containsKey

@Deprecated
public static <K,
V> boolean containsKey(Map<K,V> map,
 K key)

Deprecated.

Since empty maps are no longer represented by null, invoke Map.containsKey(java.lang.Object) directly now.

Checks if a key is contained in the map.

values

@Deprecated
public static <K,
V> Collection<V> values(Map<K,V> map)

Deprecated.

Since empty maps are no longer represented by null, invoke Map.values() directly now.

Gets the value collection.

valuesCopy

public static <K,
V> Collection<V> valuesCopy(Map<K,V> map)

Performs a shallow copy of the value collection.

copy

public static <K,
V> Map<K,V> copy(Map<K,V> map)

Performs a shallow copy of a map. The map is assumed to have been created by MinimalMap and to be used through MinimalMap.

unmodifiable

public static <K,
V> Map<K,V> unmodifiable(Map<K,V> map)

Gets an unmodifiable wrapper around this map. May or may not wrap this map itself.