Summary: Ctors | Methods | Inherited Methods

SparseArrayCompat

Kotlin |Java

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 `index`th 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 `index`th 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 `index`th key-value mapping that this SparseArray stores.

Inherited methods

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()`

Public constructors

SparseArrayCompat

public SparseArrayCompat ()

Creates a new SparseArray containing no mappings.

SparseArrayCompat

public 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. If you supply an initial capacity of 0, the sparse array will be initialized with a light-weight representation not requiring any additional array allocations.

Parameters
`initialCapacity`	`int`

Public methods

append

public 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.

Parameters
`key`	`int`
`value`	`E`

clear

public void clear ()

Removes all key-value mappings from this SparseArray.

clone

public SparseArrayCompat<E> clone ()

Returns
`SparseArrayCompat<E>`

containsKey

public boolean containsKey (int key)

Returns true if the specified key is mapped.

Parameters
`key`	`int`

Returns
`boolean`

containsValue

public boolean containsValue (E value)

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

Parameters
`value`	`E`

Returns
`boolean`

delete

public void delete (int key)

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

Parameters
`key`	`int`

get

public 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.

Parameters
`key`	`int`
`valueIfKeyNotFound`	`E`

Returns
`E`

get

public E get (int key)

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

Parameters
`key`	`int`

Returns
`E`

indexOfKey

public 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.

Parameters
`key`	`int`

Returns
`int`

indexOfValue

public 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.

Beware that this is a linear search, unlike lookups by key, and that multiple keys can map to the same value and this will find only one of them.

Note also that unlike most collections' indexOf methods, this method compares values using == rather than equals.

Parameters
`value`	`E`

Returns
`int`

isEmpty

public boolean isEmpty ()

Return true if size() is 0.

Returns
`boolean`	true if size() is 0.

keyAt

public 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.

Parameters
`index`	`int`

Returns
`int`

put

public 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.

Parameters
`key`	`int`
`value`	`E`

putAll

public void putAll (SparseArrayCompat<? extends E> other)

Copies all of the mappings from the other to this map. The effect of this call is equivalent to that of calling put(int, Object) on this map once for each mapping from key to value in other.

Parameters
`other`	`SparseArrayCompat`

putIfAbsent

public 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.

Parameters
`key`	`int`: The key under which to store the value.
`value`	`E`: The value to store for the given key.

Returns
`E`	Returns the value that was stored for the given key, or null if there was no such key.

remove

public boolean remove (int key, 
                Object value)

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

Parameters
`key`	`int`: The key of the mapping to remove.
`value`	`Object`: The value expected to be mapped to the key.

Returns
`boolean`	Returns true if the mapping was removed.

remove

public void remove (int key)

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

Parameters
`key`	`int`

removeAt

public void removeAt (int index)

Removes the mapping at the specified index.

Parameters
`index`	`int`

removeAtRange

public void removeAtRange (int index, 
                int size)

Remove a range of mappings as a batch.

Parameters
`index`	`int`: Index to begin at
`size`	`int`: Number of mappings to remove

replace

public E replace (int key, 
                E value)

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

Parameters
`key`	`int`: The key of the mapping to replace.
`value`	`E`: The value to store for the given key.

Returns
`E`	Returns the previous mapped value or null.

replace

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

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

Parameters
`key`	`int`: The key of the mapping to replace.
`oldValue`	`E`: The value expected to be mapped to the key.
`newValue`	`E`: The value to store for the given key.

Returns
`boolean`	Returns true if the value was replaced.

setValueAt

public 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.

Parameters
`index`	`int`
`value`	`E`

size

public int size ()

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

Returns
`int`

toString

public String toString ()

This implementation composes a string by iterating over its mappings. If this map contains itself as a value, the string "(this Map)" will appear in its place.

Returns
`String`

valueAt

public 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.

Parameters
`index`	`int`

Returns
`E`