Added in API level 16

Summary: Ctors | Methods | Inherited Methods

LongSparseArray

Kotlin |Java

public class LongSparseArray
extends Object implements Cloneable

java.lang.Object
↳	android.util.LongSparseArray<E>

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

Public methods
`void`	`append(long 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 LongSparseArray.
`LongSparseArray<E>`	`clone()` Creates and returns a copy of this object.
`void`	`delete(long key)` Removes the mapping from the specified key, if there was any.
`E`	`get(long key)` Gets the Object mapped from the specified key, or `null` if no such mapping has been made.
`E`	`get(long key, E valueIfKeyNotFound)` Gets the Object mapped from the specified key, or the specified Object if no such mapping has been made.
`int`	`indexOfKey(long 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.
`long`	`keyAt(int index)` Given an index in the range `0...size()-1`, returns the key from the `index`th key-value mapping that this LongSparseArray stores.
`void`	`put(long 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`	`remove(long key)` Alias for `delete(long)`.
`void`	`removeAt(int index)` Removes the mapping at the specified index.
`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 LongSparseArray stores.
`int`	`size()` Returns the number of key-value mappings that this LongSparseArray currently stores.
`String`	`toString()` Returns a string representation of the object. 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 LongSparseArray stores.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

LongSparseArray

Added in API level 16

public LongSparseArray ()

Creates a new LongSparseArray containing no mappings.

LongSparseArray

Added in API level 16

public LongSparseArray (int initialCapacity)

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.

Parameters
`initialCapacity`	`int`

Public methods

append

Added in API level 16

public void append (long 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`	`long`
`value`	`E`

clear

Added in API level 16

public void clear ()

Removes all key-value mappings from this LongSparseArray.

clone

Added in API level 16

public LongSparseArray<E> clone ()

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:

 x.clone() != x

will be true, and that the expression:

 x.clone().getClass() == x.getClass()

will be true, but these are not absolute requirements. While it is typically the case that:

 x.clone().equals(x)

will be true, this is not an absolute requirement.

By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().

By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.

Returns
`LongSparseArray<E>`	a clone of this instance.

delete

Added in API level 16

public void delete (long key)

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

Parameters
`key`	`long`

get

Added in API level 16

public E get (long key)

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

Parameters
`key`	`long`

Returns
`E`

get

Added in API level 16

public E get (long key, 
                E valueIfKeyNotFound)

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

Parameters
`key`	`long`
`valueIfKeyNotFound`	`E`

Returns
`E`

indexOfKey

Added in API level 16

public int indexOfKey (long 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`	`long`

Returns
`int`

indexOfValue

Added in API level 16

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.

Parameters
`value`	`E`

Returns
`int`

keyAt

Added in API level 16

public long keyAt (int index)

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.

For indices outside of the range 0...size()-1, the behavior is undefined for apps targeting Build.VERSION_CODES.P and earlier, and an ArrayIndexOutOfBoundsException is thrown for apps targeting Build.VERSION_CODES.Q and later.

Parameters
`index`	`int`

Returns
`long`

put

Added in API level 16

public void put (long 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`	`long`
`value`	`E`

remove

Added in API level 16

public void remove (long key)

Alias for delete(long).

Parameters
`key`	`long`

removeAt

Added in API level 16

public void removeAt (int index)

Removes the mapping at the specified index.

Parameters
`index`	`int`

setValueAt

Added in API level 16

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 LongSparseArray stores.

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

size

Added in API level 16

public int size ()

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

Returns
`int`

toString

Added in API level 16

public String toString ()

Returns a string representation of the object.

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`	a string representation of the object.

valueAt

Added in API level 16

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 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.

Parameters
`index`	`int`

Returns
`E`