ArrayMap

public class ArrayMap
extends SimpleArrayMap<K, V> implements Map<K, V>

ArrayMap is a generic key->value mapping data structure that is designed to be more memory efficient than a traditional HashMap, this implementation is a version of the platform's android.util.ArrayMap that can be used on older versions of the platform. It keeps its mappings in an array data structure -- an integer array of hash codes for each item, and an Object array of the key/value pairs. This allows it to avoid having to create an extra object for every entry put in to the map, and it also tries to control the growth of the size of these arrays more aggressively (since growing them only requires copying the entries in the array, not rebuilding a hash map).

If you don't need the standard Java container APIs provided here (iterators etc), consider using SimpleArrayMap instead.

Note that this implementation is not intended to be appropriate for data structures that may contain large numbers of items. It is generally slower than a traditional HashMap, since lookups require a binary search and adds and removes require inserting and deleting entries in the array. For containers holding up to hundreds of items, the performance difference is not significant, less than 50%.

Because this container is intended to better balance memory use, unlike most other standard Java containers it will shrink its array as items are removed from it. Currently you have no control over this shrinking -- if you set a capacity and then remove an item, it may reduce the capacity to better match the current size. In the future an explicit call to set the capacity should turn off this aggressive shrinking behavior.

Summary

Inherited methods
From class android.support.v4.util.SimpleArrayMap void clear() Make the array map empty. boolean containsKey(Object key) Check whether a key exists in the array. boolean containsValue(Object value) Check whether a value exists in the array. void ensureCapacity(int minimumCapacity) Ensure the array map can hold at least minimumCapacity items. boolean equals(Object object) This implementation returns false if the object is not a Map or SimpleArrayMap, or if the maps have different sizes. V get(Object key) Retrieve a value from the array. int hashCode() int indexOfKey(Object key) Returns the index of a key in the set. boolean isEmpty() Return true if the array map contains no items. K keyAt(int index) Return the key at the given index in the array. V put(K key, V value) Add a new value to the array map. void putAll(SimpleArrayMap<? extends K, ? extends V> array) Perform a put(Object, Object) of all key/value pairs in array V remove(Object key) Remove an existing key from the array map. V removeAt(int index) Remove the key/value mapping at the given index. V setValueAt(int index, V value) Set the value at a given index in the array. int size() Return the number of items in this array map. String toString() This implementation composes a string by iterating over its mappings. V valueAt(int index) Return the value at the given index in the array.
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait(long arg0, int arg1) final void wait(long arg0) final void wait()
From interface java.util.Map abstract void clear() default V compute(K arg0, BiFunction<? super K, ? super V, ? extends V> arg1) default V computeIfAbsent(K arg0, Function<? super K, ? extends V> arg1) default V computeIfPresent(K arg0, BiFunction<? super K, ? super V, ? extends V> arg1) abstract boolean containsKey(Object arg0) abstract boolean containsValue(Object arg0) abstract Set<Entry<K, V>> entrySet() abstract boolean equals(Object arg0) default void forEach(BiConsumer<? super K, ? super V> arg0) abstract V get(Object arg0) default V getOrDefault(Object arg0, V arg1) abstract int hashCode() abstract boolean isEmpty() abstract Set<K> keySet() default V merge(K arg0, V arg1, BiFunction<? super V, ? super V, ? extends V> arg2) abstract V put(K arg0, V arg1) abstract void putAll(Map<? extends K, ? extends V> arg0) default V putIfAbsent(K arg0, V arg1) default boolean remove(Object arg0, Object arg1) abstract V remove(Object arg0) default boolean replace(K arg0, V arg1, V arg2) default V replace(K arg0, V arg1) default void replaceAll(BiFunction<? super K, ? super V, ? extends V> arg0) abstract int size() abstract Collection<V> values()

Public constructors

ArrayMap ()

ArrayMap (int capacity)

ArrayMap (SimpleArrayMap map)

Public methods

boolean containsAll (Collection<?> collection)

Set<Entry<K, V>> entrySet ()

Set<K> keySet ()

void putAll (Map<? extends K, ? extends V> map)

boolean removeAll (Collection<?> collection)

boolean retainAll (Collection<?> collection)

Collection<V> values ()