程序包 org.beetl.core.util

类 LongSparseArray<E>

java.lang.Object

org.beetl.core.util.LongSparseArray<E>

所有已实现的接口:

Cloneable

public class LongSparseArray<E>
extends Object
implements Cloneable

SparseIntArray 的内部是通过两个数组对数据进行存储的， key 为 long 数组， value 为 Object 数组 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).

构造器概要

构造器

构造器	说明
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.

方法概要

修饰符和类型	方法	说明
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()
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.
int	indexOfValueByValue(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 indexth 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 indexth key-value mapping that this LongSparseArray stores.
int	size()	Returns the number of key-value mappings that this LongSparseArray currently stores.
String	toString()
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.

从类继承的方法 java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

构造器详细资料

LongSparseArray

public LongSparseArray()

Creates a new LongSparseArray containing no mappings.

LongSparseArray

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.

方法详细资料

clone

public LongSparseArray<E> clone()

覆盖:

clone 在类中 Object

get

public E get(long key)

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

get

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.

delete

public void delete(long key)

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

remove

public void remove(long key)

Alias for delete(long).

removeAt

public void removeAt(int index)

Removes the mapping at the specified index.

put

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.

size

public int size()

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

keyAt

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.

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 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.

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 LongSparseArray stores.

indexOfKey

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.

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.

indexOfValueByValue

public int indexOfValueByValue(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 this method uses equals unlike indexOfValue.

clear

public void clear()

Removes all key-value mappings from this LongSparseArray.

append

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.

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.

覆盖:

toString 在类中 Object