java.lang.Object | ||
↳ | android.support.v4.util.SimpleArrayMap <K, V> | |
↳ | android.support.v4.util.ArrayMap<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
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.
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
|
||||||||||
|
Create a new ArrayMap with a given initial capacity.
|
||||||||||
|
Create a new ArrayMap with the mappings from the given ArrayMap.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
Determine if the array map contains all of the keys in the given collection.
|
||||||||||
|
Return a
Set
for iterating over and interacting with all mappings
in the array map.
|
||||||||||
|
Return a
Set
for iterating over and interacting with all keys
in the array map.
|
||||||||||
|
Perform a
put(Object, Object)
of all key/value pairs in
map
|
||||||||||
|
Remove all keys in the array map that exist in the given collection.
|
||||||||||
|
Remove all keys in the array map that do
not
exist in the given collection.
|
||||||||||
|
Return a
Collection
for iterating over and interacting with all values
in the array map.
|
[Expand]
Inherited Methods
|
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
android.support.v4.util.SimpleArrayMap
|
|||||||||||
From class
java.lang.Object
|
|||||||||||
From interface
java.util.Map
|
Create a new ArrayMap with a given initial capacity.
Create a new ArrayMap with the mappings from the given ArrayMap.
Determine if the array map contains all of the keys in the given collection.
collection | The collection whose contents are to be checked against. |
---|
Return a
Set
for iterating over and interacting with all mappings
in the array map.
Note: this is a very inefficient way to access the array contents, it requires generating a number of temporary objects.
Note:
the semantics of this Set are subtly different than that of a
HashMap
: most important,
the
Map.Entry
object returned by its iterator is a single
object that exists for the entire iterator, so you can
not
hold on to it
after calling
Iterator.next
.
Return a
Set
for iterating over and interacting with all keys
in the array map.
Note: this is a fairly inefficient way to access the array contents, it requires generating a number of temporary objects.
Perform a
put(Object, Object)
of all key/value pairs in
map
map | The map whose contents are to be retrieved. |
---|
Remove all keys in the array map that exist in the given collection.
collection | The collection whose contents are to be used to remove keys. |
---|
Remove all keys in the array map that do not exist in the given collection.
collection | The collection whose contents are to be used to determine which keys to keep. |
---|
Return a
Collection
for iterating over and interacting with all values
in the array map.
Note: this is a fairly inefficient way to access the array contents, it requires generating a number of temporary objects.