it.unimi.dsi.fastutil.ints
Class Int2IntOpenHashMap

java.lang.Object
  it.unimi.dsi.fastutil.ints.AbstractInt2IntFunction
      it.unimi.dsi.fastutil.ints.AbstractInt2IntMap
          it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap

All Implemented Interfaces:

Function<Integer,Integer>, Hash, Int2IntFunction, Int2IntMap, Serializable, Cloneable, Map<Integer,Integer>

public class Int2IntOpenHashMap
extends AbstractInt2IntMap
implements Serializable, Cloneable, Hash

A type-specific hash map with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a map. The table is enlarged as needed when new entries are created, but it is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

The enlargement speed is controlled by the growth factor, a positive number. If the growth factor is p, then the table is enlarged each time roughly by a factor 2^p/16. By default, p is Hash.DEFAULT_GROWTH_FACTOR, which means that the table is doubled at each enlargement, but one can easily set more or less aggressive policies by calling growthFactor(int) (note that the growth factor is not serialized: deserialized tables gets the default growth factor).

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.ints.AbstractInt2IntMap

AbstractInt2IntMap.BasicEntry

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash

Hash.Strategy<K>

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.ints.Int2IntMap

Int2IntMap.Entry, Int2IntMap.FastEntrySet

Field Summary

static long

serialVersionUID

Fields inherited from interface it.unimi.dsi.fastutil.Hash

DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR

Constructor Summary

Int2IntOpenHashMap()
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Int2IntOpenHashMap(int n)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Int2IntOpenHashMap(int[] k, int[] v)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.

Int2IntOpenHashMap(int[] k, int[] v, float f)
Creates a new hash map using the elements of two parallel arrays.

Int2IntOpenHashMap(Int2IntMap m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.

Int2IntOpenHashMap(Int2IntMap m, float f)
Creates a new hash map copying a given type-specific one.

Int2IntOpenHashMap(int n, float f)
Creates a new hash map.

Int2IntOpenHashMap(Map<? extends Integer,? extends Integer> m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.

Int2IntOpenHashMap(Map<? extends Integer,? extends Integer> m, float f)
Creates a new hash map copying a given one.

Method Summary

void	clear() Removes all associations from this function (optional operation).
Object	clone() Returns a deep copy of this map.
boolean	containsKey(int k) Checks whether the given value is contained in AbstractInt2IntMap.keySet().
boolean	containsValue(int v) Checks whether the given value is contained in AbstractInt2IntMap.values().
int	get(int k) Returns the value to which the given key is mapped.
Integer	get(Integer ok)
int	growthFactor() Gets the growth factor.
void	growthFactor(int growthFactor) Sets the growth factor.
int	hashCode() Returns a hash code for this map.
Int2IntMap.FastEntrySet	int2IntEntrySet() Returns a type-specific set view of the mappings contained in this map.
boolean	isEmpty()
IntSet	keySet() Returns a type-specific-set view of the keys of this map.
Integer	put(Integer ok, Integer ov) Delegates to the corresponding type-specific method, taking care of returning null on a missing key.
int	put(int k, int v) Adds a pair to the map.
boolean	rehash() Rehashes this map without changing the table size.
int	remove(int k) Removes the mapping with the given key.
Integer	remove(Object ok) Delegates to the corresponding type-specific method, taking care of returning null on a missing key.
int	size() Returns the intended number of keys in this function, or -1 if no such number exists.
boolean	trim() Rehashes the map, making the table as small as possible.
boolean	trim(int n) Rehashes this map if the table is too large.
IntCollection	values() Returns a type-specific-set view of the values of this map.

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractInt2IntMap

containsValue, entrySet, equals, putAll, toString

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractInt2IntFunction

containsKey, defaultReturnValue, defaultReturnValue, get

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.ints.Int2IntFunction

defaultReturnValue, defaultReturnValue

Methods inherited from interface it.unimi.dsi.fastutil.Function

containsKey, get

Methods inherited from interface java.util.Map

containsKey, get

Field Detail

serialVersionUID

public static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

Int2IntOpenHashMap

public Int2IntOpenHashMap(int n,
                          float f)

Creates a new hash map. The actual table size is the least available prime greater than n/f.

Parameters:

n - the expected number of elements in the hash map.

f - the load factor.

See Also:

Hash.PRIMES

Int2IntOpenHashMap

public Int2IntOpenHashMap(int n)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

n - the expected number of elements in the hash map.

Int2IntOpenHashMap

public Int2IntOpenHashMap()

Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Int2IntOpenHashMap

public Int2IntOpenHashMap(Map<? extends Integer,? extends Integer> m,
                          float f)

Creates a new hash map copying a given one.

Parameters:

m - a Map to be copied into the new hash map.

f - the load factor.

Int2IntOpenHashMap

public Int2IntOpenHashMap(Map<? extends Integer,? extends Integer> m)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.

Parameters:

m - a Map to be copied into the new hash map.

Int2IntOpenHashMap

public Int2IntOpenHashMap(Int2IntMap m,
                          float f)

Creates a new hash map copying a given type-specific one.

Parameters:

m - a type-specific map to be copied into the new hash map.

f - the load factor.

Int2IntOpenHashMap

public Int2IntOpenHashMap(Int2IntMap m)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.

Parameters:

m - a type-specific map to be copied into the new hash map.

Int2IntOpenHashMap

public Int2IntOpenHashMap(int[] k,
                          int[] v,
                          float f)

Creates a new hash map using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

f - the load factor.

Throws:

IllegalArgumentException - if k and v have different lengths.

Int2IntOpenHashMap

public Int2IntOpenHashMap(int[] k,
                          int[] v)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

Throws:

IllegalArgumentException - if k and v have different lengths.

Method Detail

growthFactor

public void growthFactor(int growthFactor)

Sets the growth factor. Subsequent enlargements will increase the table size roughly by a multiplicative factor of 2^p/16.

Parameters:

growthFactor - the new growth factor; it must be positive.

growthFactor

public int growthFactor()

Gets the growth factor.

Returns:

the growth factor of this set.

See Also:

growthFactor(int)

put

public int put(int k,
               int v)

Description copied from interface: Int2IntFunction

Adds a pair to the map.

Specified by:

put in interface Int2IntFunction

Overrides:

put in class AbstractInt2IntFunction

Parameters:

k - the key.

v - the value.

Returns:

the old value, or the default return value if no value was present for the given key.

See Also:

Function.put(Object,Object)

put

public Integer put(Integer ok,
                   Integer ov)

Description copied from class: AbstractInt2IntFunction

Delegates to the corresponding type-specific method, taking care of returning null on a missing key.

This method must check whether the provided key is in the map using containsKey(). Thus, it probes the map twice. Implementors of subclasses should override it with a more efficient method.

Specified by:

put in interface Function<Integer,Integer>

Specified by:

put in interface Map<Integer,Integer>

Overrides:

put in class AbstractInt2IntFunction

Parameters:

ok - the key.

ov - the value.

Returns:

the old value, or null if no value was present for the given key.

See Also:

Map.put(Object,Object)

containsValue

public boolean containsValue(int v)

Description copied from class: AbstractInt2IntMap

Checks whether the given value is contained in AbstractInt2IntMap.values().

Specified by:

containsValue in interface Int2IntMap

Overrides:

containsValue in class AbstractInt2IntMap

See Also:

Map.containsValue(Object)

clear

public void clear()

Description copied from interface: Function

Removes all associations from this function (optional operation).

Specified by:

clear in interface Function<Integer,Integer>

Specified by:

clear in interface Map<Integer,Integer>

Overrides:

clear in class AbstractInt2IntFunction

See Also:

Map.clear()

containsKey

public boolean containsKey(int k)

Description copied from class: AbstractInt2IntMap

Checks whether the given value is contained in AbstractInt2IntMap.keySet().

Specified by:

containsKey in interface Int2IntFunction

Overrides:

containsKey in class AbstractInt2IntMap

See Also:

Function.containsKey(Object)

size

public int size()

Description copied from interface: Function

Returns the intended number of keys in this function, or -1 if no such number exists.

Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible.

Specified by:

size in interface Function<Integer,Integer>

Specified by:

size in interface Map<Integer,Integer>

Returns:

the intended number of keys in this function, or -1 if that number is not available.

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<Integer,Integer>

Overrides:

isEmpty in class AbstractInt2IntMap

get

public int get(int k)

Description copied from interface: Int2IntFunction

Returns the value to which the given key is mapped.

Specified by:

get in interface Int2IntFunction

Parameters:

k - the key.

Returns:

the corresponding value, or the default return value if no value was present for the given key.

See Also:

Function.get(Object)

remove

public int remove(int k)

Description copied from interface: Int2IntFunction

Removes the mapping with the given key.

Specified by:

remove in interface Int2IntFunction

Overrides:

remove in class AbstractInt2IntFunction

Returns:

the old value, or the default return value if no value was present for the given key.

See Also:

Function.remove(Object)

get

public Integer get(Integer ok)

remove

public Integer remove(Object ok)

Description copied from class: AbstractInt2IntFunction

Delegates to the corresponding type-specific method, taking care of returning null on a missing key.

This method must check whether the provided key is in the map using containsKey(). Thus, it probes the map twice. Implementors of subclasses should override it with a more efficient method.

Specified by:

remove in interface Function<Integer,Integer>

Specified by:

remove in interface Map<Integer,Integer>

Overrides:

remove in class AbstractInt2IntFunction

Returns:

the old value, or null if no value was present for the given key.

See Also:

Map.remove(Object)

int2IntEntrySet

public Int2IntMap.FastEntrySet int2IntEntrySet()

Description copied from interface: Int2IntMap

Returns a type-specific set view of the mappings contained in this map.

This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen Int2IntMap.entrySet() so that it returns an ObjectSet of objects of type Int2IntMap.Entry (the latter makes it possible to access keys and values with type-specific methods).

Specified by:

int2IntEntrySet in interface Int2IntMap

Returns:

a type-specific set view of the mappings contained in this map.

See Also:

Int2IntMap.entrySet()

keySet

public IntSet keySet()

Description copied from class: AbstractInt2IntMap

Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by AbstractInt2IntMap.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

keySet in interface Int2IntMap

Specified by:

keySet in interface Map<Integer,Integer>

Overrides:

keySet in class AbstractInt2IntMap

Returns:

a set view of the keys of this map; it may be safely cast to a type-specific interface.

See Also:

Map.keySet()

values

public IntCollection values()

Description copied from class: AbstractInt2IntMap

Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by AbstractInt2IntMap.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

values in interface Int2IntMap

Specified by:

values in interface Map<Integer,Integer>

Overrides:

values in class AbstractInt2IntMap

Returns:

a set view of the values of this map; it may be safely cast to a type-specific interface.

See Also:

Map.values()

rehash

public boolean rehash()

Rehashes this map without changing the table size.

This method should be called when the map underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.

If you need to reduce the table siza to fit exactly this map, you must use trim().

Returns:

true if there was enough memory to rehash the map, false otherwise.

See Also:

trim()

trim

public boolean trim()

Rehashes the map, making the table as small as possible.

This method rehashes to the smallest size satisfying the load factor. It can be used when the map will not be changed anymore, so to optimize access speed (by collecting deleted entries) and size.

If the table size is already the minimum possible, this method does nothing. If you want to guarantee rehashing, use rehash().

Returns:

true if there was enough memory to trim the map.

See Also:

trim(int), rehash()

trim

public boolean trim(int n)

Rehashes this map if the table is too large.

Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.

This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the map.

See Also:

trim(), rehash()

clone

public Object clone()

Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

Overrides:

clone in class Object

Returns:

a deep copy of this map.

hashCode

public int hashCode()

Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:

hashCode in interface Map<Integer,Integer>

Overrides:

hashCode in class AbstractInt2IntMap

Returns:

a hash code for this map.