com.aoindustries.util

Class MinimalMap

java.lang.Object

com.aoindustries.util.MinimalMap

public 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: null
size=1: Collections.singletonMap
size=2: LinkedHashMap

Author:

AO Industries, Inc.

Method Summary

Modifier and Type	Method and Description
static <K,V> boolean	containsKey(Map<K,V> map, K key) Checks if a key is contained in the map.
static <K,V> Map<K,V>	copy(Map<K,V> map) Performs a shallow copy of a map.
static <K,V> V	get(Map<K,V> map, K key) Gets an element from a map.
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 list.
static <K,V> Collection<V>	values(Map<K,V> map) Gets the value collection.
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 Detail

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

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

Gets an element from a map.

containsKey

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

Checks if a key is contained in the map.

values

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

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 list. May or may not wrap this list itself.