ArrayMap

Kotlin |Java

class ArrayMap<K : Any!, V : Any!> : MutableMap<K, V>

kotlin.Any
↳	android.util.ArrayMap

ArrayMap is a generic key->value mapping data structure that is designed to be more memory efficient than a traditional java.util.HashMap. 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).

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.

This structure is NOT thread-safe.

Summary

Public constructors
`ArrayMap()` Create a new empty ArrayMap.
`ArrayMap(capacity: Int)` Create a new ArrayMap with a given initial capacity.
`ArrayMap(map: ArrayMap<K, V>!)` Create a new ArrayMap with the mappings from the given ArrayMap.

Public methods
Unit	`clear()` Make the array map empty.
Boolean	`containsAll(collection: MutableCollection<*>!)` Determine if the array map contains all of the keys in the given collection.
Boolean	`containsKey(key: K)` Check whether a key exists in the array.
Boolean	`containsValue(value: V)` Check whether a value exists in the array.
Unit	`ensureCapacity(minimumCapacity: Int)` Ensure the array map can hold at least minimumCapacity items.
Boolean	`equals(other: Any?)` Indicates whether some other object is "equal to" this one.
Unit	`forEach(action: BiConsumer<in K, in V>)` Performs the given action for all elements in the stored order.
V?	`get(key: K)` Retrieve a value from the array.
Int	`hashCode()` Returns a hash code value for the object.
Int	`indexOfKey(key: Any!)` Returns the index of a key in the set.
Int	`indexOfValue(value: Any!)` Returns an index for which `valueAt` would return the specified value, or a negative number if no keys map to the specified value.
Boolean	`isEmpty()` Return true if the array map contains no items.
K	`keyAt(index: Int)` Return the key at the given index in the array.
V?	`put(key: K, value: V)` Add a new value to the array map.
Unit	`putAll(array: ArrayMap<out K, out V>!)` Perform a `put(java.lang.Object,java.lang.Object)` of all key/value pairs in array
Unit	`putAll(from: Map<out K, V>)` Perform a `put(java.lang.Object,java.lang.Object)` of all key/value pairs in map
V?	`remove(key: K)` Remove an existing key from the array map.
Boolean	`removeAll(collection: MutableCollection<*>!)` Remove all keys in the array map that exist in the given collection.
V	`removeAt(index: Int)` Remove the key/value mapping at the given index.
Unit	`replaceAll(function: BiFunction<in K, in V, out V>)` Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
Boolean	`retainAll(collection: MutableCollection<>!)` Remove all keys in the array map that do not* exist in the given collection.
V	`setValueAt(index: Int, value: V)` Set the value at a given index in the array.
String	`toString()` Returns a string representation of the object.
V	`valueAt(index: Int)` Return the value at the given index in the array.

Properties
MutableSet<MutableEntry<K, V>>	`entries` Return a `java.util.Set` for iterating over and interacting with all mappings in the array map.
MutableSet<K>	`keys` Return a `java.util.Set` for iterating over and interacting with all keys in the array map.
Int	`size` Return the number of items in this array map.
MutableCollection<V>	`values` Return a `java.util.Collection` for iterating over and interacting with all values in the array map.

Exceptions
`java.lang.ClassCastException`	if the key is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified key is null and this map does not permit null keys (optional)

Exceptions
`java.lang.ClassCastException`	if the value is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified value is null and this map does not permit null values (optional)

Parameters
`obj`	the reference object with which to compare.
`o`	object to be compared for equality with this map
`object`	This value may be `null`.

Exceptions
`java.lang.NullPointerException`	if the specified action is null
`java.util.ConcurrentModificationException`	if an entry is found to be removed during iteration

Parameters
`key`	K: The key under which to store the value. If this key already exists in the array, its value will be replaced.
`value`	V: The value to store for the given key.

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map
`java.lang.ClassCastException`	if the class of the specified key or value prevents it from being stored in this map
`java.lang.NullPointerException`	if the specified key or value is null and this map does not permit null keys or values
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map

Parameters
`m`	mappings to be stored in this map
`map`	The map whose contents are to be retrieved.

Exceptions
`java.lang.UnsupportedOperationException`	if the `putAll` operation is not supported by this map
`java.lang.ClassCastException`	if the class of a key or value in the specified map prevents it from being stored in this map
`java.lang.NullPointerException`	if the specified map is null, or if this map does not permit null keys or values, and the specified map contains null keys or values
`java.lang.IllegalArgumentException`	if some property of a key or value in the specified map prevents it from being stored in this map

Exceptions
`java.lang.UnsupportedOperationException`	if the `remove` operation is not supported by this map
`java.lang.ClassCastException`	if the key is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified key is null and this map does not permit null keys (optional)

Exceptions
`java.lang.UnsupportedOperationException`	if the `set` operation is not supported by this map's entry set iterator.
`java.lang.ClassCastException`	if a replacement value is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if function or a replacement value is null, and this map does not permit null keys or values (optional)
`java.lang.IllegalArgumentException`	if some property of a replacement value prevents it from being stored in this map (optional)
`java.util.ConcurrentModificationException`	if an entry is found to be removed during iteration

Parameters
`index`	Int: The desired index, must be between 0 and `size()`-1.
`value`	V: The new value to store at this index.

ArrayMap

Summary

Public constructors

ArrayMap

ArrayMap

ArrayMap

Public methods

clear

containsAll

containsKey

containsValue

ensureCapacity

equals

forEach

get

hashCode

indexOfKey

indexOfValue

isEmpty

keyAt

put

putAll

putAll

remove

removeAll

removeAt

replaceAll

retainAll

setValueAt

toString

valueAt

Properties

entries

keys

size

values