it.unimi.dsi.fastutil.bytes
Class Byte2CharOpenHashMap

java.lang.Object
  it.unimi.dsi.fastutil.bytes.AbstractByte2CharFunction
      it.unimi.dsi.fastutil.bytes.AbstractByte2CharMap
          it.unimi.dsi.fastutil.bytes.Byte2CharOpenHashMap

All Implemented Interfaces:

Byte2CharFunction, Byte2CharMap, Function<Byte,Character>, Hash, Serializable, Cloneable, Map<Byte,Character>

public class Byte2CharOpenHashMap
extends AbstractByte2CharMap
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 by doubling its size 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.

Warning: The implementation of this class has significantly changed in fastutil 6.1.0. Please read the comments about this issue in the section “Faster Hash Tables” of the overview.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.bytes.AbstractByte2CharMap

AbstractByte2CharMap.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.bytes.Byte2CharMap

Byte2CharMap.Entry, Byte2CharMap.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

Byte2CharOpenHashMap()
Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Byte2CharOpenHashMap(byte[] k, char[] v)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.

Byte2CharOpenHashMap(byte[] k, char[] v, float f)
Creates a new hash map using the elements of two parallel arrays.

Byte2CharOpenHashMap(Byte2CharMap m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.

Byte2CharOpenHashMap(Byte2CharMap m, float f)
Creates a new hash map copying a given type-specific one.

Byte2CharOpenHashMap(int expected)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Byte2CharOpenHashMap(int expected, float f)
Creates a new hash map.

Byte2CharOpenHashMap(Map<? extends Byte,? extends Character> m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.

Byte2CharOpenHashMap(Map<? extends Byte,? extends Character> m, float f)
Creates a new hash map copying a given one.

Method Summary

Byte2CharMap.FastEntrySet	byte2CharEntrySet() Returns a type-specific set view of the mappings contained in this map.
void	clear() Removes all associations from this function (optional operation).
Byte2CharOpenHashMap	clone() Returns a deep copy of this map.
boolean	containsKey(byte k) Checks whether the given value is contained in AbstractByte2CharMap.keySet().
boolean	containsValue(char v) Checks whether the given value is contained in AbstractByte2CharMap.values().
char	get(byte k) Returns the value to which the given key is mapped.
Character	get(Byte ok)
int	growthFactor() Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
void	growthFactor(int growthFactor) Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
int	hashCode() Returns a hash code for this map.
boolean	isEmpty()
ByteSet	keySet() Returns a type-specific-set view of the keys of this map.
char	put(byte k, char v) Adds a pair to the map.
Character	put(Byte ok, Character ov) Delegates to the corresponding type-specific method, taking care of returning null on a missing key.
boolean	rehash() Deprecated. A no-op.
char	remove(byte k) Removes the mapping with the given key.
Character	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.
CharCollection	values() Returns a type-specific-set view of the values of this map.

Methods inherited from class it.unimi.dsi.fastutil.bytes.AbstractByte2CharMap

containsValue, entrySet, equals, putAll, toString

Methods inherited from class it.unimi.dsi.fastutil.bytes.AbstractByte2CharFunction

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.bytes.Byte2CharFunction

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

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(int expected,
                            float f)

Creates a new hash map.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash set.

f - the load factor.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(int expected)

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

Parameters:

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

Byte2CharOpenHashMap

public Byte2CharOpenHashMap()

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

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(Map<? extends Byte,? extends Character> 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.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(Map<? extends Byte,? extends Character> 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.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(Byte2CharMap 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.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(Byte2CharMap 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.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(byte[] k,
                            char[] 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.

Byte2CharOpenHashMap

public Byte2CharOpenHashMap(byte[] k,
                            char[] 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

put

public char put(byte k,
                char v)

Description copied from interface: Byte2CharFunction

Adds a pair to the map.

Specified by:

put in interface Byte2CharFunction

Overrides:

put in class AbstractByte2CharFunction

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 Character put(Byte ok,
                     Character ov)

Description copied from class: AbstractByte2CharFunction

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<Byte,Character>

Specified by:

put in interface Map<Byte,Character>

Overrides:

put in class AbstractByte2CharFunction

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)

remove

public char remove(byte k)

Description copied from interface: Byte2CharFunction

Removes the mapping with the given key.

Specified by:

remove in interface Byte2CharFunction

Overrides:

remove in class AbstractByte2CharFunction

Returns:

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

See Also:

Function.remove(Object)

remove

public Character remove(Object ok)

Description copied from class: AbstractByte2CharFunction

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<Byte,Character>

Specified by:

remove in interface Map<Byte,Character>

Overrides:

remove in class AbstractByte2CharFunction

Returns:

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

See Also:

Map.remove(Object)

get

public Character get(Byte ok)

get

public char get(byte k)

Description copied from interface: Byte2CharFunction

Returns the value to which the given key is mapped.

Specified by:

get in interface Byte2CharFunction

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)

containsKey

public boolean containsKey(byte k)

Description copied from class: AbstractByte2CharMap

Checks whether the given value is contained in AbstractByte2CharMap.keySet().

Specified by:

containsKey in interface Byte2CharFunction

Overrides:

containsKey in class AbstractByte2CharMap

See Also:

Function.containsKey(Object)

containsValue

public boolean containsValue(char v)

Description copied from class: AbstractByte2CharMap

Checks whether the given value is contained in AbstractByte2CharMap.values().

Specified by:

containsValue in interface Byte2CharMap

Overrides:

containsValue in class AbstractByte2CharMap

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<Byte,Character>

Specified by:

clear in interface Map<Byte,Character>

Overrides:

clear in class AbstractByte2CharFunction

See Also:

Map.clear()

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<Byte,Character>

Specified by:

size in interface Map<Byte,Character>

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<Byte,Character>

Overrides:

isEmpty in class AbstractByte2CharMap

growthFactor

@Deprecated
public void growthFactor(int growthFactor)

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

A no-op for backward compatibility.

Parameters:

growthFactor - unused.

growthFactor

@Deprecated
public int growthFactor()

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

Gets the growth factor (2).

Returns:

the growth factor of this set, which is fixed (2).

See Also:

growthFactor(int)

byte2CharEntrySet

public Byte2CharMap.FastEntrySet byte2CharEntrySet()

Description copied from interface: Byte2CharMap

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 Byte2CharMap.entrySet() so that it returns an ObjectSet of objects of type Byte2CharMap.Entry (the latter makes it possible to access keys and values with type-specific methods).

Specified by:

byte2CharEntrySet in interface Byte2CharMap

Returns:

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

See Also:

Byte2CharMap.entrySet()

keySet

public ByteSet keySet()

Description copied from class: AbstractByte2CharMap

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

The view is backed by the set returned by AbstractByte2CharMap.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 Byte2CharMap

Specified by:

keySet in interface Map<Byte,Character>

Overrides:

keySet in class AbstractByte2CharMap

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 CharCollection values()

Description copied from class: AbstractByte2CharMap

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

The view is backed by the set returned by AbstractByte2CharMap.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 Byte2CharMap

Specified by:

values in interface Map<Byte,Character>

Overrides:

values in class AbstractByte2CharMap

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

@Deprecated
public boolean rehash()

Deprecated. A no-op.

A no-op for backward compatibility. The kind of tables implemented by this class never need rehashing.

If you need to reduce the table size to fit exactly this set, use trim().

Returns:

true.

See Also:

trim()

trim

public boolean trim()

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

This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.

Returns:

true if there was enough memory to trim the map.

See Also:

trim(int)

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()

clone

public Byte2CharOpenHashMap 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<Byte,Character>

Overrides:

hashCode in class AbstractByte2CharMap

Returns:

a hash code for this map.