com.badlogic.gdx.utils

Class IntIntMap

java.lang.Object

com.badlogic.gdx.utils.IntIntMap

All Implemented Interfaces:

Iterable<IntIntMap.Entry>

public class IntIntMap
extends Object
implements Iterable<IntIntMap.Entry>

An unordered map where the keys and values are unboxed ints. No allocation is done except when growing the table size.

This class performs fast contains and remove (typically O(1), worst case O(n) but that is rare in practice). Add may be slightly slower, depending on hash collisions. Hashcodes are rehashed to reduce collisions and the need to resize. Load factors greater than 0.91 greatly increase the chances to resize to the next higher POT size.

Unordered sets and maps are not designed to provide especially fast iteration. Iteration is faster with OrderedSet and OrderedMap.

This implementation uses linear probing with the backward shift algorithm for removal. Hashcodes are rehashed using Fibonacci hashing, instead of the more common power-of-two mask, to better distribute poor hashCodes (see Malte Skarupke's blog post). Linear probing continues to work even when all hashCodes collide, just more slowly.

Author:

Nathan Sweet, Tommy Ettinger

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	IntIntMap.Entries
static class	IntIntMap.Entry
static class	IntIntMap.Keys
static class	IntIntMap.Values

Field Summary

Fields

Modifier and Type	Field and Description
int	size

Constructor Summary

Constructors

Constructor and Description
IntIntMap() Creates a new map with an initial capacity of 51 and a load factor of 0.8.
IntIntMap(int initialCapacity) Creates a new map with a load factor of 0.8.
IntIntMap(int initialCapacity, float loadFactor) Creates a new map with the specified initial capacity and load factor.
IntIntMap(IntIntMap map) Creates a new map identical to the specified map.

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 / loadFactor, if they are larger.
boolean	containsKey(int 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 accommodate the specified number of additional items / loadFactor.
IntIntMap.Entries	entries() Returns an iterator for the entries in the map.
boolean	equals(Object obj)
int	findKey(int value, int notFound) Returns the key for the specified value, or null if it is not in the map.
int	get(int key, int defaultValue)
int	getAndIncrement(int key, int defaultValue, int increment) Returns the key's current value and increments the stored value.
int	hashCode()
boolean	isEmpty() Returns true if the map is empty.
Iterator<IntIntMap.Entry>	iterator()
IntIntMap.Keys	keys() Returns an iterator for the keys in the map.
boolean	notEmpty() Returns true if the map has one or more items.
void	put(int key, int value)
int	put(int key, int value, int defaultValue) Returns the old value associated with the specified key, or the specified default value.
void	putAll(IntIntMap map)
int	remove(int key, int defaultValue) Returns the value for the removed key, or the default value if the key is not in the map.
void	shrink(int maximumCapacity) Reduces the size of the backing arrays to be the specified capacity / locateKey, or less.
String	toString()
IntIntMap.Values	values() Returns an iterator for the values in the map.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

size

public int size

Constructor Detail

IntIntMap

public IntIntMap()

Creates a new map with an initial capacity of 51 and a load factor of 0.8.

IntIntMap

public IntIntMap(int initialCapacity)

Creates a new map with a load factor of 0.8.

Parameters:

initialCapacity - If not a power of two, it is increased to the next nearest power of two.

IntIntMap

public IntIntMap(int initialCapacity,
                 float loadFactor)

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

Parameters:

initialCapacity - If not a power of two, it is increased to the next nearest power of two.

IntIntMap

public IntIntMap(IntIntMap map)

Creates a new map identical to the specified map.

Method Detail

put

public void put(int key,
                int value)

put

public int put(int key,
               int value,
               int defaultValue)

Returns the old value associated with the specified key, or the specified default value.

putAll

public void putAll(IntIntMap map)

get

public int get(int key,
               int defaultValue)

getAndIncrement

public int getAndIncrement(int 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 and defaultValue is returned.

remove

public int remove(int key,
                  int defaultValue)

Returns the value for the removed key, or the default value if the key is not in the map.

notEmpty

public boolean notEmpty()

Returns true if the map has one or more items.

isEmpty

public boolean isEmpty()

Returns true if the map is empty.

shrink

public void shrink(int maximumCapacity)

Reduces the size of the backing arrays to be the specified capacity / locateKey, or less. If the capacity is already less, nothing is done. If the map contains more items than the specified capacity, the next highest power of two capacity is used instead.

clear

public void clear(int maximumCapacity)

Clears the map and reduces the size of the backing arrays to be the specified capacity / loadFactor, 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(int key)

findKey

public int findKey(int value,
                   int notFound)

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 accommodate the specified number of additional items / loadFactor. Useful before adding many items to avoid multiple backing array resizes.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

iterator

public Iterator<IntIntMap.Entry> iterator()

Specified by:

iterator in interface Iterable<IntIntMap.Entry>

entries

public IntIntMap.Entries entries()

Returns an iterator for the entries in the map. Remove is supported.

If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the IntIntMap.Entries constructor for nested or multithreaded iteration.

values

public IntIntMap.Values values()

Returns an iterator for the values in the map. Remove is supported.

If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the IntIntMap.Entries constructor for nested or multithreaded iteration.

keys

public IntIntMap.Keys keys()

Returns an iterator for the keys in the map. Remove is supported.

If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the IntIntMap.Entries constructor for nested or multithreaded iteration.