SparseArrayCompat

public class SparseArrayCompat
extends Object implements Cloneable

java.lang.Object
   ↳ androidx.collection.SparseArrayCompat<E>


SparseArrays map integers to Objects. Unlike a normal array of Objects, there can be gaps in the indices. It is intended to be more memory efficient than using a HashMap to map Integers to Objects, both because it avoids auto-boxing keys and its data structure doesn't rely on an extra entry object for each mapping.

Note that this container keeps its mappings in an array data structure, using a binary search to find keys. The 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%.

To help with performance, the container includes an optimization when removing keys: instead of compacting its array immediately, it leaves the removed entry marked as deleted. The entry can then be re-used for the same key, or compacted later in a single garbage collection step of all removed entries. This garbage collection will need to be performed at any time the array needs to be grown or the the map size or entry values are retrieved.

It is possible to iterate over the items in this container using keyAt(int) and valueAt(int). Iterating over the keys using keyAt(int) with ascending values of the index will return the keys in ascending order, or the values corresponding to the keys in ascending order in the case of valueAt(int).

Summary

Public constructors

SparseArrayCompat()

Creates a new SparseArray containing no mappings.

SparseArrayCompat(int initialCapacity)

Creates a new SparseArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings.

Public methods

void append(int key, E value)

Puts a key/value pair into the array, optimizing for the case where the key is greater than all existing keys in the array.

void clear()

Removes all key-value mappings from this SparseArray.

SparseArrayCompat<E> clone()
boolean containsKey(int key)

Returns true if the specified key is mapped.

boolean containsValue(E value)

Returns true if the specified value is mapped from any key.

void delete(int key)

This method is deprecated. Alias for remove(int).

E get(int key, E valueIfKeyNotFound)

Gets the Object mapped from the specified key, or the specified Object if no such mapping has been made.

E get(int key)

Gets the Object mapped from the specified key, or null if no such mapping has been made.

int indexOfKey(int key)

Returns the index for which keyAt(int) would return the specified key, or a negative number if the specified key is not mapped.

int indexOfValue(E value)

Returns an index for which valueAt(int) would return the specified key, or a negative number if no keys map to the specified value.

boolean isEmpty()

Return true if size() is 0.

int keyAt(int index)

Given an index in the range 0...size()-1, returns the key from the indexth key-value mapping that this SparseArray stores.

void put(int key, E value)

Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.

void putAll(SparseArrayCompat<? extends E> other)

Copies all of the mappings from the other to this map.

E putIfAbsent(int key, E value)

Add a new value to the array map only if the key does not already have a value or it is mapped to null.

boolean remove(int key, Object value)

Remove an existing key from the array map only if it is currently mapped to value.

void remove(int key)

Removes the mapping from the specified key, if there was any.

void removeAt(int index)

Removes the mapping at the specified index.

void removeAtRange(int index, int size)

Remove a range of mappings as a batch.

E replace(int key, E value)

Replace the mapping for key only if it is already mapped to a value.

boolean replace(int key, E oldValue, E newValue)

Replace the mapping for key only if it is already mapped to a value.

void setValueAt(int index, E value)

Given an index in the range 0...size()-1, sets a new value for the indexth key-value mapping that this SparseArray stores.

int size()

Returns the number of key-value mappings that this SparseArray currently stores.

String toString()

This implementation composes a string by iterating over its mappings.

E valueAt(int index)

Given an index in the range 0...size()-1, returns the value from the indexth key-value mapping that this SparseArray stores.

Inherited methods

Public constructors

SparseArrayCompat

public SparseArrayCompat ()

Creates a new SparseArray containing no mappings. <