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java.lang.Objectit.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap
it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceSortedMap
it.unimi.dsi.fastutil.objects.Object2ReferenceLinkedOpenCustomHashMap
A type-specific linked hash map with 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 2p/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).
This class implements the interface of a sorted map, so to allow easy
access of the iteration order: for instance, you can get the first key
in iteration order with firstKey()
without having to create an
iterator; however, this class partially violates the SortedMap
contract because all submap methods throw an exception and comparator()
returns always null
.
The iterators provided by the views of this class using are type-specific
list iterators. However, creation of an
iterator using a starting point is going to be very expensive, as the chosen
starting point must be linearly searched for, unless it is lastKey()
,
in which case the iterator is created in constant time.
Note that deletions in a linked table require scanning the list until the element to be removed is found. The only exceptions are the first element, the last element, and deletions performed using an iterator.
Hash
,
HashCommon
,
Serialized FormNested Class Summary |
Nested classes inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap |
AbstractObject2ReferenceMap.BasicEntry |
Nested classes inherited from class it.unimi.dsi.fastutil.Hash |
Hash.Strategy |
Nested classes inherited from class it.unimi.dsi.fastutil.objects.Object2ReferenceMap |
Object2ReferenceMap.Entry |
Field Summary | |
static long |
serialVersionUID
|
Fields inherited from interface it.unimi.dsi.fastutil.Hash |
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED |
Constructor Summary | |
Object2ReferenceLinkedOpenCustomHashMap(Hash.Strategy strategy)
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries
and Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
Object2ReferenceLinkedOpenCustomHashMap(int n,
float f,
Hash.Strategy strategy)
Creates a new hash map. |
|
Object2ReferenceLinkedOpenCustomHashMap(int n,
Hash.Strategy strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
Object2ReferenceLinkedOpenCustomHashMap(Map m,
float f,
Hash.Strategy strategy)
Creates a new hash map copying a given one. |
|
Object2ReferenceLinkedOpenCustomHashMap(Map m,
Hash.Strategy strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one. |
|
Object2ReferenceLinkedOpenCustomHashMap(Object[] k,
Object[] v,
float f,
Hash.Strategy strategy)
Creates a new hash map using the elements of two parallel arrays. |
|
Object2ReferenceLinkedOpenCustomHashMap(Object[] k,
Object[] v,
Hash.Strategy strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays. |
|
Object2ReferenceLinkedOpenCustomHashMap(Object2ReferenceMap m,
float f,
Hash.Strategy strategy)
Creates a new hash map copying a given type-specific one. |
|
Object2ReferenceLinkedOpenCustomHashMap(Object2ReferenceMap m,
Hash.Strategy strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one. |
Method Summary | |
void |
clear()
|
Object |
clone()
Returns a deep copy of this map. |
Comparator |
comparator()
|
boolean |
containsKey(Object k)
Checks whether the given value is contained in keySet() . |
boolean |
containsValue(Object v)
Checks whether the given value is contained in values() . |
Set |
entrySet()
|
Object |
firstKey()
Returns the first key of this map in iteration order. |
Object |
get(Object k)
|
int |
growthFactor()
Gets the growth factor. |
void |
growthFactor(int growthFactor)
Sets the growth factor. |
int |
hashCode()
Returns a hash code for this map. |
SortedMap |
headMap(Object to)
Delegates to the corresponding type-specific method. |
boolean |
isEmpty()
|
Set |
keySet()
Returns a type-specific-sorted-set view of the keys of this map. |
Object |
lastKey()
Returns the last key of this map in iteration order. |
Object |
put(Object k,
Object v)
|
boolean |
rehash()
Rehashes this map without changing the table size. |
Object |
remove(Object k)
|
int |
size()
|
Hash.Strategy |
strategy()
Returns the hashing strategy. |
SortedMap |
subMap(Object from,
Object to)
Delegates to the corresponding type-specific method. |
SortedMap |
tailMap(Object from)
Delegates to the corresponding type-specific method. |
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. |
Collection |
values()
Returns a type-specific-set view of the values of this map. |
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap |
defaultReturnValue, defaultReturnValue, equals, getDefRetValue, putAll, setDefRetValue, toString |
Methods inherited from class java.lang.Object |
getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceMap |
defaultReturnValue, defaultReturnValue, getDefRetValue, setDefRetValue |
Methods inherited from interface java.util.Map |
equals, putAll |
Field Detail |
public static final long serialVersionUID
Constructor Detail |
public Object2ReferenceLinkedOpenCustomHashMap(int n, float f, Hash.Strategy strategy)
n
/f
.
n
- the expected number of elements in the hash map.f
- the load factor.strategy
- the strategy.Hash.PRIMES
public Object2ReferenceLinkedOpenCustomHashMap(int n, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor.
n
- the expected number of elements in the hash map.strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Hash.Strategy strategy)
Hash.DEFAULT_INITIAL_SIZE
entries
and Hash.DEFAULT_LOAD_FACTOR
as load factor.
strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Map m, float f, Hash.Strategy strategy)
m
- a Map
to be copied into the new hash map.f
- the load factor.strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Map m, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor copying a given one.
m
- a Map
to be copied into the new hash map.strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Object2ReferenceMap m, float f, Hash.Strategy strategy)
m
- a type-specific map to be copied into the new hash map.f
- the load factor.strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Object2ReferenceMap m, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor copying a given type-specific one.
m
- a type-specific map to be copied into the new hash map.strategy
- the strategy.public Object2ReferenceLinkedOpenCustomHashMap(Object[] k, Object[] v, float f, Hash.Strategy strategy)
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.strategy
- the strategy.
IllegalArgumentException
- if k
and v
have different lengths.public Object2ReferenceLinkedOpenCustomHashMap(Object[] k, Object[] v, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor using the elements of two parallel arrays.
k
- the array of keys of the new hash map.v
- the array of corresponding values in the new hash map.strategy
- the strategy.
IllegalArgumentException
- if k
and v
have different lengths.Method Detail |
public Hash.Strategy strategy()
public void growthFactor(int growthFactor)
growthFactor
- the new growth factor; it must be positive.public int growthFactor()
growthFactor(int)
public Object put(Object k, Object v)
put
in interface Map
put
in class AbstractObject2ReferenceMap
public boolean containsValue(Object v)
AbstractObject2ReferenceMap
AbstractObject2ReferenceMap.values()
.
containsValue
in interface Map
containsValue
in class AbstractObject2ReferenceMap
public void clear()
clear
in interface Map
clear
in class AbstractObject2ReferenceMap
public Object firstKey()
firstKey
in interface SortedMap
firstKey
in class AbstractObject2ReferenceSortedMap
public Object lastKey()
lastKey
in interface SortedMap
lastKey
in class AbstractObject2ReferenceSortedMap
public Comparator comparator()
comparator
in interface SortedMap
public SortedMap tailMap(Object from)
AbstractObject2ReferenceSortedMap
tailMap
in interface SortedMap
tailMap
in class AbstractObject2ReferenceSortedMap
public SortedMap headMap(Object to)
AbstractObject2ReferenceSortedMap
headMap
in interface SortedMap
headMap
in class AbstractObject2ReferenceSortedMap
public SortedMap subMap(Object from, Object to)
AbstractObject2ReferenceSortedMap
subMap
in interface SortedMap
subMap
in class AbstractObject2ReferenceSortedMap
public boolean containsKey(Object k)
AbstractObject2ReferenceMap
AbstractObject2ReferenceMap.keySet()
.
containsKey
in interface Map
containsKey
in class AbstractObject2ReferenceMap
public int size()
size
in interface Map
public boolean isEmpty()
isEmpty
in interface Map
isEmpty
in class AbstractObject2ReferenceMap
public Object get(Object k)
get
in interface Map
public Object remove(Object k)
remove
in interface Map
remove
in class AbstractObject2ReferenceMap
public Set entrySet()
entrySet
in interface Map
public Set keySet()
AbstractObject2ReferenceSortedMap
The view is backed by the sorted set returned by Map.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.
keySet
in interface Map
keySet
in class AbstractObject2ReferenceSortedMap
public Collection values()
AbstractObject2ReferenceMap
The view is backed by the set returned by Map.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.
values
in interface Map
values
in class AbstractObject2ReferenceMap
public boolean rehash()
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()
.
true
if there was enough memory to rehash the map, false
otherwise.trim()
public boolean trim()
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 optimise 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()
.
trim(int)
,
rehash()
public boolean trim(int n)
Let N be the smallest table size that can hold
max(n,
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.
size()
)
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.
n
- the threshold for the trimming.
trim()
,
rehash()
public Object clone()
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.
public int hashCode()
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.
hashCode
in interface Map
hashCode
in class AbstractObject2ReferenceMap
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