it.unimi.dsi.fastutil.ints
Class Int2IntOpenHashMap

java.lang.Object
  extended by it.unimi.dsi.fastutil.ints.AbstractInt2IntFunction
      extended by it.unimi.dsi.fastutil.ints.AbstractInt2IntMap
          extended by it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap
All Implemented Interfaces:
Function<java.lang.Integer,java.lang.Integer>, Hash, Int2IntFunction, Int2IntMap, java.io.Serializable, java.lang.Cloneable, java.util.Map<java.lang.Integer,java.lang.Integer>

public class Int2IntOpenHashMap
extends AbstractInt2IntMap
implements java.io.Serializable, java.lang.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.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
 
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 initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Int2IntOpenHashMap(int expected)
          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 expected, float f)
          Creates a new hash map.
Int2IntOpenHashMap(java.util.Map<? extends java.lang.Integer,? extends java.lang.Integer> m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Int2IntOpenHashMap(java.util.Map<? extends java.lang.Integer,? extends java.lang.Integer> m, float f)
          Creates a new hash map copying a given one.
 
Method Summary
 int add(int k, int incr)
          Deprecated. use addTo() instead; having the same name of a Set method turned out to be a recipe for disaster.
 int addTo(int k, int incr)
          Adds an increment to value currently associated with a key.
 void clear()
          Removes all associations from this function (optional operation).
 Int2IntOpenHashMap 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.
 java.lang.Integer get(java.lang.Integer 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.
 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.
 java.lang.Integer put(java.lang.Integer ok, java.lang.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()
          Deprecated. A no-op.
 int remove(int k)
          Removes the mapping with the given key.
 java.lang.Integer remove(java.lang.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
 

Constructor Detail

Int2IntOpenHashMap

public Int2IntOpenHashMap(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.

Int2IntOpenHashMap

public Int2IntOpenHashMap(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.

Int2IntOpenHashMap

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


Int2IntOpenHashMap

public Int2IntOpenHashMap(java.util.Map<? extends java.lang.Integer,? extends java.lang.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(java.util.Map<? extends java.lang.Integer,? extends java.lang.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:
java.lang.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:
java.lang.IllegalArgumentException - if k and v have different lengths.
Method Detail

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 java.lang.Integer put(java.lang.Integer ok,
                             java.lang.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<java.lang.Integer,java.lang.Integer>
Specified by:
put in interface java.util.Map<java.lang.Integer,java.lang.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)

add

@Deprecated
public int add(int k,
                          int incr)
Deprecated. use addTo() instead; having the same name of a Set method turned out to be a recipe for disaster.

Adds an increment to value currently associated with a key.

Parameters:
k - the key.
incr - the increment.
Returns:
the old value, or the default return value if no value was present for the given key.

addTo

public int addTo(int k,
                 int incr)
Adds an increment to value currently associated with a key.

Note that this method respects the default return value semantics: when called with a key that does not currently appears in the map, the key will be associated with the default return value plus the given increment.

Parameters:
k - the key.
incr - the increment.
Returns:
the old value, or the default return value if no value was present for the given key.

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)

remove

public java.lang.Integer remove(java.lang.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<java.lang.Integer,java.lang.Integer>
Specified by:
remove in interface java.util.Map<java.lang.Integer,java.lang.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)

get

public java.lang.Integer get(java.lang.Integer ok)

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)

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)

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<java.lang.Integer,java.lang.Integer>
Specified by:
clear in interface java.util.Map<java.lang.Integer,java.lang.Integer>
Overrides:
clear in class AbstractInt2IntFunction
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<java.lang.Integer,java.lang.Integer>
Specified by:
size in interface java.util.Map<java.lang.Integer,java.lang.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 java.util.Map<java.lang.Integer,java.lang.Integer>
Overrides:
isEmpty in class AbstractInt2IntMap

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)

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 Map.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 java.util.Map<java.lang.Integer,java.lang.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 java.util.Map<java.lang.Integer,java.lang.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

@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 Int2IntOpenHashMap 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 java.lang.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 java.util.Map<java.lang.Integer,java.lang.Integer>
Overrides:
hashCode in class AbstractInt2IntMap
Returns:
a hash code for this map.