LongSparseArray

open class LongSparseArray<E : Any!> : Cloneable
kotlin.Any
   ↳ androidx.collection.LongSparseArray

SparseArray mapping longs 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 Longs 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

Creates a new LongSparseArray containing no mappings.

<init>(initialCapacity: Int)

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

Public methods

open Unit
append(key: Long, 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

Removes all key-value mappings from this LongSparseArray.

open LongSparseArray<E>

open Boolean

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: Long)

open E?
get(key: Long)

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

open E
get(key: Long, valueIfKeyNotFound: E)

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

open 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

Return true if size() is 0.

open Long
keyAt(index: Int)

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

open Unit
put(key: Long, 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: LongSparseArray<out E>)

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

open E?
putIfAbsent(key: Long, 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: Long)

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

open Boolean
remove(key: Long, 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 E?
replace(key: Long, value: E)

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

open Boolean
replace(key: Long, 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 indexth key-value mapping that this LongSparseArray stores.

open Int

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

open String

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 indexth key-value mapping that this LongSparseArray stores.

Extension functions

From androidx.collection
operator Boolean

Returns true if the collection contains key.

Unit
LongSparseArray<T>.forEach(action: (key: Long, value: T) -> Unit)

Performs the given action for each key/value entry.

T
LongSparseArray<T>.getOrDefault(key: Long, defaultValue: T)

Return the value corresponding to key, or defaultValue when not present.

T
LongSparseArray<T>.getOrElse(key: Long, defaultValue: () -> T)

Return the value corresponding to key, or from defaultValue when not present.

Boolean

Return true when the collection contains elements.

LongIterator

Return an iterator over the collection's keys.

operator LongSparseArray<T>

Creates a new collection by adding or replacing entries from other.

Boolean
LongSparseArray<T>.remove(key: Long, value: T)

Removes the entry for key only if it is mapped to value.

operator Unit
LongSparseArray<T>.set(key: Long, value: T)

Allows the use of the index operator for storing values in the collection.

Iterator<T>

Return an iterator over the collection's values.

Extension properties

From androidx.collection
Int

Returns the number of key/value pairs in the collection.

Public constructors

<init>

LongSparseArray()

Creates a new LongSparseArray containing no mappings.

<init>

LongSparseArray(initialCapacity: Int)

Creates a new LongSparseArray 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: Long, 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 LongSparseArray.

clone

open fun clone(): LongSparseArray<E>

containsKey

open fun containsKey(key: Long): 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: Long): Unit

Deprecated: Alias for remove(long).

get

@Nullable open fun get(key: Long): E?

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

get

open fun get(key: Long, 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: Long): 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.

isEmpty

open fun isEmpty(): Boolean

Return true if size() is 0.

Return
Boolean: true if size() is 0.

keyAt

open fun keyAt(index: Int): Long

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

The keys corresponding to indices in ascending order are guaranteed to be in ascending order, e.g., keyAt(0) will return the smallest key and keyAt(size()-1) will return the largest key.

put

open fun put(key: Long, 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: LongSparseArray<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(long, Object) on this map once for each mapping from key to value in other.

putIfAbsent

@Nullable open fun putIfAbsent(key: Long, 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 Long: The key under which to store the value.
value Long: 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: Long): Unit

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

remove

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

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

Parameters
key Long: The key of the mapping to remove.
value Long: 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.

replace

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

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

Parameters
key Long: The key of the mapping to replace.
value Long: The value to store for the given key.
Return
E?: Returns the previous mapped value or null.

replace

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

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

Parameters
key Long: The key of the mapping to replace.
oldValue Long: The value expected to be mapped to the key.
newValue Long: 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 LongSparseArray stores.

size

open fun size(): Int

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

The values corresponding to indices in ascending order are guaranteed to be associated with keys in ascending order, e.g., valueAt(0) will return the value associated with the smallest key and valueAt(size()-1) will return the value associated with the largest key.