com.esotericsoftware.kryo.util

Class IdentityObjectIntMap<K>

java.lang.Object

com.esotericsoftware.kryo.util.IdentityObjectIntMap<K>

public class IdentityObjectIntMap<K>
extends Object

An unordered map where identity comparison is used for keys and the values are ints. This implementation is a cuckoo hash map using 3 hashes (if table size is less than 2^16) or 4 hashes (if table size is greater than or equal to 2^16), random walking, and a small stash for problematic keys. Null keys are not allowed. No allocation is done except when growing the table size.

This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the next higher POT size.

Author:

Nathan Sweet

Field Summary

Fields

Modifier and Type	Field and Description
int	size

Constructor Summary

Constructors

Constructor and Description
IdentityObjectIntMap() Creates a new map with an initial capacity of 32 and a load factor of 0.8.
IdentityObjectIntMap(int initialCapacity) Creates a new map with a load factor of 0.8.
IdentityObjectIntMap(int initialCapacity, float loadFactor) Creates a new map with the specified initial capacity and load factor.

Method Summary

Modifier and Type	Method and Description
void	clear()
void	clear(int maximumCapacity) Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.
boolean	containsKey(K key)
boolean	containsValue(int value) Returns true if the specified value is in the map.
void	ensureCapacity(int additionalCapacity) Increases the size of the backing array to acommodate the specified number of additional items.
K	findKey(int value) Returns the key for the specified value, or null if it is not in the map.
int	get(K key, int defaultValue)
int	getAndIncrement(K key, int defaultValue, int increment) Returns the key's current value and increments the stored value.
void	put(K key, int value)
int	remove(K key, int defaultValue)
void	shrink(int maximumCapacity) Reduces the size of the backing arrays to be the specified capacity or less.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

size

public int size

Constructor Detail

IdentityObjectIntMap

public IdentityObjectIntMap()

Creates a new map with an initial capacity of 32 and a load factor of 0.8. This map will hold 25 items before growing the backing table.

IdentityObjectIntMap

public IdentityObjectIntMap(int initialCapacity)

Creates a new map with a load factor of 0.8. This map will hold initialCapacity * 0.8 items before growing the backing table.

IdentityObjectIntMap

public IdentityObjectIntMap(int initialCapacity,
                            float loadFactor)

Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity * loadFactor items before growing the backing table.

Method Detail

put

public void put(K key,
                int value)

get

public int get(K key,
               int defaultValue)

Parameters:

defaultValue - Returned if the key was not associated with a value.

getAndIncrement

public int getAndIncrement(K key,
                           int defaultValue,
                           int increment)

Returns the key's current value and increments the stored value. If the key is not in the map, defaultValue + increment is put into the map.

remove

public int remove(K key,
                  int defaultValue)

shrink

public void shrink(int maximumCapacity)

Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is already less, nothing is done. If the map contains more items than the specified capacity, nothing is done.

clear

public void clear(int maximumCapacity)

Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.

clear

public void clear()

containsValue

public boolean containsValue(int value)

Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.

containsKey

public boolean containsKey(K key)

findKey

public K findKey(int value)

Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.

ensureCapacity

public void ensureCapacity(int additionalCapacity)

Increases the size of the backing array to acommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes.

toString

public String toString()

Overrides:

toString in class Object