open class SparseLongArray : Cloneable
SparseLongArrays map integers to longs. Unlike a normal array of longs, there can be gaps in the indices. It is intended to be more memory efficient than using a HashMap to map Integers to Longs, both because it avoids auto-boxing keys and values 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%.
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 SparseLongArray containing no mappings. |
|
|
Creates a new SparseLongArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings. |
|
| Public methods | |
|---|---|
| open 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. |
| open Unit |
Removes all key-value mappings from this SparseLongArray. |
| open SparseLongArray |
Creates and returns a copy of this object. |
| open Unit |
Removes the mapping from the specified key, if there was any. |
| open Long |
Gets the long mapped from the specified key, or |
| open Long |
Gets the long mapped from the specified key, or the specified value if no such mapping has been made. |
| open Int |
Returns the index for which |
| open Int |
Returns an index for which |
| open Int |
Given an index in the range |
| open Unit |
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 |
Removes the mapping at the given index. |
| open Int |
Returns the number of key-value mappings that this SparseLongArray currently stores. |
| open String |
Returns a string representation of the object. |
| open Long |
Given an index in the range |
Public constructors
SparseLongArray
SparseLongArray()
Creates a new SparseLongArray containing no mappings.
SparseLongArray
SparseLongArray(initialCapacity: Int)
Creates a new SparseLongArray 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: Long
): 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.
clone
open fun clone(): SparseLongArray
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.
| Return | |
|---|---|
SparseLongArray |
a clone of this instance. |
| Exceptions | |
|---|---|
java.lang.CloneNotSupportedException |
if the object's class does not support the Cloneable interface. Subclasses that override the clone method can also throw this exception to indicate that an instance cannot be cloned. |
delete
open fun delete(key: Int): Unit
Removes the mapping from the specified key, if there was any.
get
open fun get(key: Int): Long
Gets the long mapped from the specified key, or 0 if no such mapping has been made.
get
open fun get(
key: Int,
valueIfKeyNotFound: Long
): Long
Gets the long mapped from the specified key, or the specified value 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: Long): 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.
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 SparseLongArray 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 android.os.Build.VERSION_CODES#P and earlier, and an ArrayIndexOutOfBoundsException is thrown for apps targeting android.os.Build.VERSION_CODES#Q and later.
put
open fun put(
key: Int,
value: Long
): Unit
Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.
size
open fun size(): Int
Returns the number of key-value mappings that this SparseLongArray currently stores.
toString
open fun toString(): String
Returns a string representation of the object.
This implementation composes a string by iterating over its mappings.
| Return | |
|---|---|
String |
a string representation of the object. |
valueAt
open fun valueAt(index: Int): Long
Given an index in the range 0...size()-1, returns the value from the indexth key-value mapping that this SparseLongArray 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.
For indices outside of the range 0...size()-1, the behavior is undefined for apps targeting android.os.Build.VERSION_CODES#P and earlier, and an ArrayIndexOutOfBoundsException is thrown for apps targeting android.os.Build.VERSION_CODES#Q and later.