SparseArrayCompat

Kotlin |Java

open class SparseArrayCompat<E : Any!> : Cloneable

kotlin.Any
↳	androidx.collection.SparseArrayCompat

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
`<init>()` Creates a new SparseArray containing no mappings.
`<init>(initialCapacity: Int)` Creates a new SparseArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings.

Public methods
open Unit	`append(key: Int, value: E)` Puts a key/value pair into the array, optimizing for the case where the key is greater than all existing keys in the array.
open Unit	`clear()` Removes all key-value mappings from this SparseArray.
open SparseArrayCompat<E>	`clone()`
open Boolean	`containsKey(key: Int)` Returns true if the specified key is mapped.
open Boolean	`containsValue(value: E)` Returns true if the specified value is mapped from any key.
open Unit	`delete(key: Int)`
open E?	`get(key: Int)` Gets the Object mapped from the specified key, or `null` if no such mapping has been made.
open E	`get(key: Int, valueIfKeyNotFound: E)` Gets the Object mapped from the specified key, or the specified Object if no such mapping has been made.
open Int	`indexOfKey(key: Int)` Returns the index for which `keyAt` would return the specified key, or a negative number if the specified key is not mapped.
open Int	`indexOfValue(value: E)` Returns an index for which `valueAt` would return the specified key, or a negative number if no keys map to the specified value.
open Boolean	`isEmpty()` Return true if size() is 0.
open Int	`keyAt(index: Int)` Given an index in the range `0...size()-1`, returns the key from the `index`th key-value mapping that this SparseArray stores.
open Unit	`put(key: Int, value: E)` Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.
open Unit	`putAll(@NonNull other: SparseArrayCompat<out E>)` Copies all of the mappings from the `other` to this map.
open E?	`putIfAbsent(key: Int, value: E)` Add a new value to the array map only if the key does not already have a value or it is mapped to `null`.
open Unit	`remove(key: Int)` Removes the mapping from the specified key, if there was any.
open Boolean	`remove(key: Int, value: Any!)` Remove an existing key from the array map only if it is currently mapped to `value`.
open Unit	`removeAt(index: Int)` Removes the mapping at the specified index.
open Unit	`removeAtRange(index: Int, size: Int)` Remove a range of mappings as a batch.
open E?	`replace(key: Int, value: E)` Replace the mapping for `key` only if it is already mapped to a value.
open Boolean	`replace(key: Int, oldValue: E, newValue: E)` Replace the mapping for `key` only if it is already mapped to a value.
open Unit	`setValueAt(index: Int, value: E)` Given an index in the range `0...size()-1`, sets a new value for the `index`th key-value mapping that this SparseArray stores.
open Int	`size()` Returns the number of key-value mappings that this SparseArray currently stores.
open String	`toString()` This implementation composes a string by iterating over its mappings.
open E	`valueAt(index: Int)` Given an index in the range `0...size()-1`, returns the value from the `index`th key-value mapping that this SparseArray stores.

Extension functions

From androidx.collection

operator Boolean	`SparseArrayCompat<T>.contains(key: Int)` Returns true if the collection contains key.
Unit	`SparseArrayCompat<T>.forEach(action: (key: Int, value: T) -> Unit)` Performs the given action for each key/value entry.
T	`SparseArrayCompat<T>.getOrDefault(key: Int, defaultValue: T)` Return the value corresponding to key, or defaultValue when not present.
T	`SparseArrayCompat<T>.getOrElse(key: Int, defaultValue: () -> T)` Return the value corresponding to key, or from defaultValue when not present.
Boolean	`SparseArrayCompat<T>.isNotEmpty()` Return true when the collection contains elements.
IntIterator	`SparseArrayCompat<T>.keyIterator()` Return an iterator over the collection's keys.
operator SparseArrayCompat<T>	`SparseArrayCompat<T>.plus(other: SparseArrayCompat<T>)` Creates a new collection by adding or replacing entries from other.
Boolean	`SparseArrayCompat<T>.remove(key: Int, value: T)` Removes the entry for key only if it is mapped to value.
operator Unit	`SparseArrayCompat<T>.set(key: Int, value: T)` Allows the use of the index operator for storing values in the collection.
Iterator<T>	`SparseArrayCompat<T>.valueIterator()` Return an iterator over the collection's values.

Extension properties

From androidx.collection

Int	`size` Returns the number of key/value pairs in the collection.

Public constructors

<init>

SparseArrayCompat()

Creates a new SparseArray containing no mappings.

<init>

SparseArrayCompat(initialCapacity: Int)

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.

Public methods

append

open fun append(
    key: Int, 
    value: E
): Unit

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

clear

open fun clear(): Unit

Removes all key-value mappings from this SparseArray.

clone

open fun clone(): SparseArrayCompat<E>

containsKey

open fun containsKey(key: Int): Boolean

Returns true if the specified key is mapped.

containsValue

open fun containsValue(value: E): Boolean

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

delete

open fun delete(key: Int): Unit

Deprecated: Alias for remove(int).

get

@Nullable open fun get(key: Int): E?

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

get

open fun get(
    key: Int, 
    valueIfKeyNotFound: E
): E

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

indexOfKey

open fun indexOfKey(key: Int): Int

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

indexOfValue

open fun indexOfValue(value: E): Int

Returns an index for which valueAt 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.

isEmpty

open fun isEmpty(): Boolean

Return true if size() is 0.

Return
`Boolean`	true if size() is 0.

keyAt

open fun keyAt(index: Int): Int

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

put

open fun put(
    key: Int, 
    value: E
): Unit

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

putAll

open fun putAll(@NonNull other: SparseArrayCompat<out E>): Unit

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.

putIfAbsent

@Nullable open fun putIfAbsent(
    key: Int, 
    value: E
): E?

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.

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

remove

open fun remove(key: Int): Unit

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

remove

open fun remove(
    key: Int, 
    value: Any!
): Boolean

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`	Any!: The value expected to be mapped to the key.

Return
`Boolean`	Returns true if the mapping was removed.

removeAt

open fun removeAt(index: Int): Unit

Removes the mapping at the specified index.

removeAtRange

open fun removeAtRange(
    index: Int, 
    size: Int
): Unit

Remove a range of mappings as a batch.

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

replace

@Nullable open fun replace(
    key: Int, 
    value: E
): E?

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.

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

replace

open fun replace(
    key: Int, 
    oldValue: E, 
    newValue: E
): Boolean

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.

Return
`Boolean`	Returns true if the value was replaced.

setValueAt

open fun setValueAt(
    index: Int, 
    value: E
): Unit

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

size

open fun size(): Int

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

toString

open fun toString(): String

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.

valueAt

open fun valueAt(index: Int): E

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