K
- the type of keys maintained by this mapV
- the type of mapped valuesSerializable
, ConcurrentMap<K,V>
, Map<K,V>
public class ConcurrentHashMap<K,V> extends AbstractMap<K,V> implements ConcurrentMap<K,V>, Serializable
Hashtable
, and includes versions of methods corresponding to each method of Hashtable
. However, even though all operations are thread-safe, retrieval operations do not entail locking, and there is not any support for locking the entire table in a way that prevents all access. This class is fully interoperable with Hashtable
in programs that rely on its thread safety but not on its synchronization details. Retrieval operations (including get
) generally do not block, so may overlap with update operations (including put
and remove
). Retrievals reflect the results of the most recently completed update operations holding upon their onset. (More formally, an update operation for a given key bears a happens-before relation with any (non-null) retrieval for that key reporting the updated value.) For aggregate operations such as putAll
and clear
, concurrent retrievals may reflect insertion or removal of only some entries. Similarly, Iterators, Spliterators and Enumerations return elements reflecting the state of the hash table at some point at or since the creation of the iterator/enumeration. They do not throw ConcurrentModificationException
. However, iterators are designed to be used by only one thread at a time. Bear in mind that the results of aggregate status methods including size
, isEmpty
, and containsValue
are typically useful only when a map is not undergoing concurrent updates in other threads. Otherwise the results of these methods reflect transient states that may be adequate for monitoring or estimation purposes, but not for program control.
The table is dynamically expanded when there are too many collisions (i.e., keys that have distinct hash codes but fall into the same slot modulo the table size), with the expected average effect of maintaining roughly two bins per mapping (corresponding to a 0.75 load factor threshold for resizing). There may be much variance around this average as mappings are added and removed, but overall, this maintains a commonly accepted time/space tradeoff for hash tables. However, resizing this or any other kind of hash table may be a relatively slow operation. When possible, it is a good idea to provide a size estimate as an optional
initialCapacity
constructor argument. An additional optional loadFactor
constructor argument provides a further means of customizing initial table capacity by specifying the table density to be used in calculating the amount of space to allocate for the given number of elements. Also, for compatibility with previous versions of this class, constructors may optionally specify an expected concurrencyLevel
as an additional hint for internal sizing. Note that using many keys with exactly the same hashCode()
is a sure way to slow down performance of any hash table. To ameliorate impact, when keys are Comparable
, this class may use comparison order among keys to help break ties.
A Set
projection of a ConcurrentHashMap may be created (using newKeySet()
or newKeySet(int)
), or viewed (using keySet(Object)
when only keys are of interest, and the mapped values are (perhaps transiently) not used or all take the same mapping value.
A ConcurrentHashMap can be used as a scalable frequency map (a form of histogram or multiset) by using LongAdder
values and initializing via computeIfAbsent
. For example, to add a count to a ConcurrentHashMap<String,LongAdder> freqs
, you can use freqs.computeIfAbsent(key, k -> new LongAdder()).increment();
This class and its views and iterators implement all of the optional methods of the Map
and Iterator
interfaces.
Like Hashtable
but unlike HashMap
, this class does not allow null
to be used as a key or value.
ConcurrentHashMaps support a set of sequential and parallel bulk operations that, unlike most Stream
methods, are designed to be safely, and often sensibly, applied even with maps that are being concurrently updated by other threads; for example, when computing a snapshot summary of the values in a shared registry. There are three kinds of operation, each with four forms, accepting functions with keys, values, entries, and (key, value) pairs as arguments and/or return values. Because the elements of a ConcurrentHashMap are not ordered in any particular way, and may be processed in different orders in different parallel executions, the correctness of supplied functions should not depend on any ordering, or on any other objects or values that may transiently change while computation is in progress; and except for forEach actions, should ideally be side-effect-free. Bulk operations on Map.Entry
objects do not support method setValue
.
These bulk operations accept a parallelismThreshold
argument. Methods proceed sequentially if the current map size is estimated to be less than the given threshold. Using a value of Long.MAX_VALUE
suppresses all parallelism. Using a value of 1
results in maximal parallelism by partitioning into enough subtasks to fully utilize the ForkJoinPool.commonPool()
that is used for all parallel computations. Normally, you would initially choose one of these extreme values, and then measure performance of using in-between values that trade off overhead versus throughput.
The concurrency properties of bulk operations follow from those of ConcurrentHashMap: Any non-null result returned from get(key)
and related access methods bears a happens-before relation with the associated insertion or update. The result of any bulk operation reflects the composition of these per-element relations (but is not necessarily atomic with respect to the map as a whole unless it is somehow known to be quiescent). Conversely, because keys and values in the map are never null, null serves as a reliable atomic indicator of the current lack of any result. To maintain this property, null serves as an implicit basis for all non-scalar reduction operations. For the double, long, and int versions, the basis should be one that, when combined with any other value, returns that other value (more formally, it should be the identity element for the reduction). Most common reductions have these properties; for example, computing a sum with basis 0 or a minimum with basis MAX_VALUE.
Search and transformation functions provided as arguments should similarly return null to indicate the lack of any result (in which case it is not used). In the case of mapped reductions, this also enables transformations to serve as filters, returning null (or, in the case of primitive specializations, the identity basis) if the element should not be combined. You can create compound transformations and filterings by composing them yourself under this "null means there is nothing there now" rule before using them in search or reduce operations.
Methods accepting and/or returning Entry arguments maintain key-value associations. They may be useful for example when finding the key for the greatest value. Note that "plain" Entry arguments can be supplied using new
AbstractMap.SimpleEntry(k,v)
.
Bulk operations may complete abruptly, throwing an exception encountered in the application of a supplied function. Bear in mind when handling such exceptions that other concurrently executing functions could also have thrown exceptions, or would have done so if the first exception had not occurred.
Speedups for parallel compared to sequential forms are common but not guaranteed. Parallel operations involving brief functions on small maps may execute more slowly than sequential forms if the underlying work to parallelize the computation is more expensive than the computation itself. Similarly, parallelization may not lead to much actual parallelism if all processors are busy performing unrelated tasks.
All arguments to all task methods must be non-null.
This class is a member of the Java Collections Framework.
Modifier and Type | Class | Description |
---|---|---|
static final class |
ConcurrentHashMap.KeySetView<K, |
A view of a ConcurrentHashMap as a Set of keys, in which additions may optionally be enabled by mapping to a common value. |
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
Constructor | Description |
---|---|
ConcurrentHashMap() |
Creates a new, empty map with the default initial table size (16). |
ConcurrentHashMap |
Creates a new, empty map with an initial table size accommodating the specified number of elements without the need to dynamically resize. |
ConcurrentHashMap |
Creates a new, empty map with an initial table size based on the given number of elements ( initialCapacity ) and initial table density (loadFactor ). |
ConcurrentHashMap |
Creates a new, empty map with an initial table size based on the given number of elements ( initialCapacity ), initial table density (loadFactor ), and number of concurrently updating threads (concurrencyLevel ). |
ConcurrentHashMap |
Creates a new map with the same mappings as the given map. |
Modifier and Type | Method | Description |
---|---|---|
void |
clear() |
Removes all of the mappings from this map. |
V |
compute |
Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). |
V |
computeIfAbsent |
If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless null . |
V |
computeIfPresent |
If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value. |
boolean |
contains |
Tests if some key maps into the specified value in this table. |
boolean |
containsKey |
Tests if the specified object is a key in this table. |
boolean |
containsValue |
Returns true if this map maps one or more keys to the specified value. |
Enumeration |
elements() |
Returns an enumeration of the values in this table. |
Set |
entrySet() |
Returns a Set view of the mappings contained in this map. |
boolean |
equals |
Compares the specified object with this map for equality. |
void |
forEach |
Performs the given action for each (key, value). |
<U> void |
forEach |
Performs the given action for each non-null transformation of each (key, value). |
void |
forEachEntry |
Performs the given action for each entry. |
<U> void |
forEachEntry |
Performs the given action for each non-null transformation of each entry. |
void |
forEachKey |
Performs the given action for each key. |
<U> void |
forEachKey |
Performs the given action for each non-null transformation of each key. |
void |
forEachValue |
Performs the given action for each value. |
<U> void |
forEachValue |
Performs the given action for each non-null transformation of each value. |
V |
get |
Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key. |
V |
getOrDefault |
Returns the value to which the specified key is mapped, or the given default value if this map contains no mapping for the key. |
int |
hashCode() |
Returns the hash code value for this Map , i.e., the sum of, for each key-value pair in the map, key.hashCode() ^ value.hashCode() . |
boolean |
isEmpty() |
Returns true if this map contains no key-value mappings. |
Enumeration |
keys() |
Returns an enumeration of the keys in this table. |
ConcurrentHashMap.KeySetView |
keySet() |
Returns a Set view of the keys contained in this map. |
ConcurrentHashMap.KeySetView |
keySet |
Returns a Set view of the keys in this map, using the given common mapped value for any additions (i.e., Collection.add(E) and Collection.addAll(Collection) ). |
long |
mappingCount() |
Returns the number of mappings. |
V |
merge |
If the specified key is not already associated with a (non-null) value, associates it with the given value. |
static <K> ConcurrentHashMap.KeySetView |
newKeySet() |
Creates a new Set backed by a ConcurrentHashMap from the given type to Boolean.TRUE . |
static <K> ConcurrentHashMap.KeySetView |
newKeySet |
Creates a new Set backed by a ConcurrentHashMap from the given type to Boolean.TRUE . |
V |
put |
Maps the specified key to the specified value in this table. |
void |
putAll |
Copies all of the mappings from the specified map to this one. |
V |
putIfAbsent |
If the specified key is not already associated with a value, associates it with the given value. |
<U> U |
reduce |
Returns the result of accumulating the given transformation of all (key, value) pairs using the given reducer to combine values, or null if none. |
Map.Entry |
reduceEntries |
Returns the result of accumulating all entries using the given reducer to combine values, or null if none. |
<U> U |
reduceEntries |
Returns the result of accumulating the given transformation of all entries using the given reducer to combine values, or null if none. |
double |
reduceEntriesToDouble |
Returns the result of accumulating the given transformation of all entries using the given reducer to combine values, and the given basis as an identity value. |
int |
reduceEntriesToInt |
Returns the result of accumulating the given transformation of all entries using the given reducer to combine values, and the given basis as an identity value. |
long |
reduceEntriesToLong |
Returns the result of accumulating the given transformation of all entries using the given reducer to combine values, and the given basis as an identity value. |
K |
reduceKeys |
Returns the result of accumulating all keys using the given reducer to combine values, or null if none. |
<U> U |
reduceKeys |
Returns the result of accumulating the given transformation of all keys using the given reducer to combine values, or null if none. |
double |
reduceKeysToDouble |
Returns the result of accumulating the given transformation of all keys using the given reducer to combine values, and the given basis as an identity value. |
int |
reduceKeysToInt |
Returns the result of accumulating the given transformation of all keys using the given reducer to combine values, and the given basis as an identity value. |
long |
reduceKeysToLong |
Returns the result of accumulating the given transformation of all keys using the given reducer to combine values, and the given basis as an identity value. |
double |
reduceToDouble |
Returns the result of accumulating the given transformation of all (key, value) pairs using the given reducer to combine values, and the given basis as an identity value. |
int |
reduceToInt |
Returns the result of accumulating the given transformation of all (key, value) pairs using the given reducer to combine values, and the given basis as an identity value. |
long |
reduceToLong |
Returns the result of accumulating the given transformation of all (key, value) pairs using the given reducer to combine values, and the given basis as an identity value. |
V |
reduceValues |
Returns the result of accumulating all values using the given reducer to combine values, or null if none. |
<U> U |
reduceValues |
Returns the result of accumulating the given transformation of all values using the given reducer to combine values, or null if none. |
double |
reduceValuesToDouble |
Returns the result of accumulating the given transformation of all values using the given reducer to combine values, and the given basis as an identity value. |
int |
reduceValuesToInt |
Returns the result of accumulating the given transformation of all values using the given reducer to combine values, and the given basis as an identity value. |
long |
reduceValuesToLong |
Returns the result of accumulating the given transformation of all values using the given reducer to combine values, and the given basis as an identity value. |
V |
remove |
Removes the key (and its corresponding value) from this map. |
boolean |
remove |
Removes the entry for a key only if currently mapped to a given value. |
V |
replace |
Replaces the entry for a key only if currently mapped to some value. |
boolean |
replace |
Replaces the entry for a key only if currently mapped to a given value. |
<U> U |
search |
Returns a non-null result from applying the given search function on each (key, value), or null if none. |
<U> U |
searchEntries |
Returns a non-null result from applying the given search function on each entry, or null if none. |
<U> U |
searchKeys |
Returns a non-null result from applying the given search function on each key, or null if none. |
<U> U |
searchValues |
Returns a non-null result from applying the given search function on each value, or null if none. |
int |
size() |
Returns the number of key-value mappings in this map. |
String |
toString() |
Returns a string representation of this map. |
Collection |
values() |
Returns a Collection view of the values contained in this map. |
clone, isEmpty, size
forEach, replaceAll
public ConcurrentHashMap()
public ConcurrentHashMap(int initialCapacity)
initialCapacity
- The implementation performs internal sizing to accommodate this many elements.IllegalArgumentException
- if the initial capacity of elements is negativepublic ConcurrentHashMap(Map<? extends K,? extends V> m)
m
- the mappublic ConcurrentHashMap(int initialCapacity, float loadFactor)
initialCapacity
) and initial table density (loadFactor
).initialCapacity
- the initial capacity. The implementation performs internal sizing to accommodate this many elements, given the specified load factor.loadFactor
- the load factor (table density) for establishing the initial table sizeIllegalArgumentException
- if the initial capacity of elements is negative or the load factor is nonpositivepublic ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel)
initialCapacity
), initial table density (loadFactor
), and number of concurrently updating threads (concurrencyLevel
).initialCapacity
- the initial capacity. The implementation performs internal sizing to accommodate this many elements, given the specified load factor.loadFactor
- the load factor (table density) for establishing the initial table sizeconcurrencyLevel
- the estimated number of concurrently updating threads. The implementation may use this value as a sizing hint.IllegalArgumentException
- if the initial capacity is negative or the load factor or concurrencyLevel are nonpositivepublic int size()
Integer.MAX_VALUE
elements, returns Integer.MAX_VALUE
.public boolean isEmpty()
true
if this map contains no key-value mappings.public V get(Object key)
null
if this map contains no mapping for the key. More formally, if this map contains a mapping from a key k
to a value v
such that key.equals(k)
, then this method returns v
; otherwise it returns null
. (There can be at most one such mapping.)
get
in interface Map<K,V>
get
in class AbstractMap<K,V>
key
- the key whose associated value is to be returnednull
if this map contains no mapping for the keyNullPointerException
- if the specified key is nullpublic boolean containsKey(Object key)
containsKey
in interface Map<K,V>
containsKey
in class AbstractMap<K,V>
key
- possible keytrue
if and only if the specified object is a key in this table, as determined by the equals
method; false
otherwiseNullPointerException
- if the specified key is nullpublic boolean containsValue(Object value)
true
if this map maps one or more keys to the specified value. Note: This method may require a full traversal of the map, and is much slower than method containsKey
.containsValue
in interface Map<K,V>
containsValue
in class AbstractMap<K,V>
value
- value whose presence in this map is to be testedtrue
if this map maps one or more keys to the specified valueNullPointerException
- if the specified value is nullpublic V put(K key, V value)
The value can be retrieved by calling the get
method with a key that is equal to the original key.
put
in interface Map<K,V>
put
in class AbstractMap<K,V>
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified keykey
, or null
if there was no mapping for key
NullPointerException
- if the specified key or value is nullpublic void putAll(Map<? extends K,? extends V> m)
public V remove(Object key)
remove
in interface Map<K,V>
remove
in class AbstractMap<K,V>
key
- the key that needs to be removedkey
, or null
if there was no mapping for key
NullPointerException
- if the specified key is nullpublic void clear()
public ConcurrentHashMap.KeySetView<K,V> keySet()
Set
view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove
, Set.remove
, removeAll
, retainAll
, and clear
operations. It does not support the add
or addAll
operations. The view's iterators and spliterators are weakly consistent.
The view's spliterator
reports Spliterator.CONCURRENT
, Spliterator.DISTINCT
, and Spliterator.NONNULL
.
public Collection<V> values()
Collection
view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove
, Collection.remove
, removeAll
, retainAll
, and clear
operations. It does not support the add
or addAll
operations. The view's iterators and spliterators are weakly consistent.
The view's spliterator
reports Spliterator.CONCURRENT
and Spliterator.NONNULL
.
public Set<Map.Entry<K,V>> entrySet()
Set
view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove
, Set.remove
, removeAll
, retainAll
, and clear
operations. The view's iterators and spliterators are weakly consistent.
The view's spliterator
reports Spliterator.CONCURRENT
, Spliterator.DISTINCT
, and Spliterator.NONNULL
.
public int hashCode()
Map
, i.e., the sum of, for each key-value pair in the map, key.hashCode() ^ value.hashCode()
.public String toString()
{}
"). Adjacent mappings are separated by the characters ", "
(comma and space). Each key-value mapping is rendered as the key followed by an equals sign ("=
") followed by the associated value.toString
in class AbstractMap<K,V>
public boolean equals(Object o)
true
if the given object is a map with the same mappings as this map. This operation may return misleading results if either map is concurrently modified during execution of this method.public V putIfAbsent(K key, V value)
map
:
if (!map.containsKey(key))
return map.put(key, value);
else
return map.get(key);
except that the action is performed atomically.putIfAbsent
in interface ConcurrentMap<K,V>
putIfAbsent
in interface Map<K,V>
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified keynull
if there was no mapping for the keyNullPointerException
- if the specified key or value is nullpublic boolean remove(Object key, Object value)
map
:
if (map.containsKey(key)
&& Objects.equals(map.get(key), value)) {
map.remove(key);
return true;
} else {
return false;
}
except that the action is performed atomically.remove
in interface ConcurrentMap<K,V>
remove
in interface Map<K,V>
key
- key with which the specified value is associatedvalue
- value expected to be associated with the specified keytrue
if the value was removedNullPointerException
- if the specified key is nullpublic boolean replace(K key, V oldValue, V newValue)
map
:
if (map.containsKey(key)
&& Objects.equals(map.get(key), oldValue)) {
map.put(key, newValue);
return true;
} else {
return false;
}
except that the action is performed atomically.replace
in interface ConcurrentMap<K,V>
replace
in interface Map<K,V>
key
- key with which the specified value is associatedoldValue
- value expected to be associated with the specified keynewValue
- value to be associated with the specified keytrue
if the value was replacedNullPointerException
- if any of the arguments are nullpublic V replace(K key, V value)
map
:
if (map.containsKey(key))
return map.put(key, value);
else
return null;
except that the action is performed atomically.replace
in interface ConcurrentMap<K,V>
replace
in interface Map<K,V>
key
- key with which the specified value is associatedvalue
- value to be associated with the specified keynull
if there was no mapping for the keyNullPointerException
- if the specified key or value is nullpublic V getOrDefault(Object key, V defaultValue)
getOrDefault
in interface ConcurrentMap<K,V>
getOrDefault
in interface Map<K,V>
key
- the key whose associated value is to be returneddefaultValue
- the value to return if this map contains no mapping for the given keyNullPointerException
- if the specified key is nullpublic V computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)
null
. The entire method invocation is performed atomically. The supplied function is invoked exactly once per invocation of this method if the key is absent, else not at all. Some attempted update operations on this map by other threads may be blocked while computation is in progress, so the computation should be short and simple. The mapping function must not modify this map during computation.
computeIfAbsent
in interface ConcurrentMap<K,V>
computeIfAbsent
in interface Map<K,V>
key
- key with which the specified value is to be associatedmappingFunction
- the function to compute a valueNullPointerException
- if the specified key or mappingFunction is nullIllegalStateException
- if the computation detectably attempts a recursive update to this map that would otherwise never completeRuntimeException
- or Error if the mappingFunction does so, in which case the mapping is left unestablishedpublic V computeIfPresent(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)
The remapping function must not modify this map during computation.
computeIfPresent
in interface ConcurrentMap<K,V>
computeIfPresent
in interface Map<K,V>
key
- key with which a value may be associatedremappingFunction
- the function to compute a valueNullPointerException
- if the specified key or remappingFunction is nullIllegalStateException
- if the computation detectably attempts a recursive update to this map that would otherwise never completeRuntimeException
- or Error if the remappingFunction does so, in which case the mapping is unchangedpublic V compute(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)
null
if there is no current mapping). The entire method invocation is performed atomically. The supplied function is invoked exactly once per invocation of this method. Some attempted update operations on this map by other threads may be blocked while computation is in progress, so the computation should be short and simple. The remapping function must not modify this map during computation.
compute
in interface ConcurrentMap<K,V>
compute
in interface Map<K,V>
key
- key with which the specified value is to be associatedremappingFunction
- the function to compute a valueNullPointerException
- if the specified key or remappingFunction is nullIllegalStateException
- if the computation detectably attempts a recursive update to this map that would otherwise never completeRuntimeException
- or Error if the remappingFunction does so, in which case the mapping is unchangedpublic V merge(K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)
null
. The entire method invocation is performed atomically. Some attempted update operations on this map by other threads may be blocked while computation is in progress, so the computation should be short and simple, and must not attempt to update any other mappings of this Map.merge
in interface ConcurrentMap<K,V>
merge
in interface Map<K,V>
key
- key with which the specified value is to be associatedvalue
- the value to use if absentremappingFunction
- the function to recompute a value if presentNullPointerException
- if the specified key or the remappingFunction is nullRuntimeException
- or Error if the remappingFunction does so, in which case the mapping is unchangedpublic boolean contains(Object value)
Note that this method is identical in functionality to containsValue(Object)
, and exists solely to ensure full compatibility with class Hashtable
, which supported this method prior to introduction of the Java Collections Framework.
value
- a value to search fortrue
if and only if some key maps to the value
argument in this table as determined by the equals
method; false
otherwiseNullPointerException
- if the specified value is nullpublic Enumeration<K> keys()
public Enumeration<V> elements()
public long mappingCount()
size()
because a ConcurrentHashMap may contain more mappings than can be represented as an int. The value returned is an estimate; the actual count may differ if there are concurrent insertions or removals.public static <K> ConcurrentHashMap.KeySetView<K,Boolean> newKeySet()
Set
backed by a ConcurrentHashMap from the given type to Boolean.TRUE
.K
- the element type of the returned setpublic static <K> ConcurrentHashMap.KeySetView<K,Boolean> newKeySet(int initialCapacity)
Set
backed by a ConcurrentHashMap from the given type to Boolean.TRUE
.K
- the element type of the returned setinitialCapacity
- The implementation performs internal sizing to accommodate this many elements.IllegalArgumentException
- if the initial capacity of elements is negativepublic ConcurrentHashMap.KeySetView<K,V> keySet(V mappedValue)
Set
view of the keys in this map, using the given common mapped value for any additions (i.e., Collection.add(E)
and Collection.addAll(Collection)
). This is of course only appropriate if it is acceptable to use the same value for all additions from this view.mappedValue
- the mapped value to use for any additionsNullPointerException
- if the mappedValue is nullpublic void forEach(long parallelismThreshold, BiConsumer<? super K,? super V> action)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelaction
- the actionpublic <U> void forEach(long parallelismThreshold, BiFunction<? super K,? super V,? extends U> transformer, Consumer<? super U> action)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case the action is not applied)action
- the actionpublic <U> U search(long parallelismThreshold, BiFunction<? super K,? super V,? extends U> searchFunction)
U
- the return type of the search functionparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelsearchFunction
- a function returning a non-null result on success, else nullpublic <U> U reduce(long parallelismThreshold, BiFunction<? super K,? super V,? extends U> transformer, BiFunction<? super U,? super U,? extends U> reducer)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case it is not combined)reducer
- a commutative associative combining functionpublic double reduceToDouble(long parallelismThreshold, ToDoubleBiFunction<? super K,? super V> transformer, double basis, DoubleBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic long reduceToLong(long parallelismThreshold, ToLongBiFunction<? super K,? super V> transformer, long basis, LongBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic int reduceToInt(long parallelismThreshold, ToIntBiFunction<? super K,? super V> transformer, int basis, IntBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic void forEachKey(long parallelismThreshold, Consumer<? super K> action)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelaction
- the actionpublic <U> void forEachKey(long parallelismThreshold, Function<? super K,? extends U> transformer, Consumer<? super U> action)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case the action is not applied)action
- the actionpublic <U> U searchKeys(long parallelismThreshold, Function<? super K,? extends U> searchFunction)
U
- the return type of the search functionparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelsearchFunction
- a function returning a non-null result on success, else nullpublic K reduceKeys(long parallelismThreshold, BiFunction<? super K,? super K,? extends K> reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelreducer
- a commutative associative combining functionpublic <U> U reduceKeys(long parallelismThreshold, Function<? super K,? extends U> transformer, BiFunction<? super U,? super U,? extends U> reducer)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case it is not combined)reducer
- a commutative associative combining functionpublic double reduceKeysToDouble(long parallelismThreshold, ToDoubleFunction<? super K> transformer, double basis, DoubleBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic long reduceKeysToLong(long parallelismThreshold, ToLongFunction<? super K> transformer, long basis, LongBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic int reduceKeysToInt(long parallelismThreshold, ToIntFunction<? super K> transformer, int basis, IntBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic void forEachValue(long parallelismThreshold, Consumer<? super V> action)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelaction
- the actionpublic <U> void forEachValue(long parallelismThreshold, Function<? super V,? extends U> transformer, Consumer<? super U> action)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case the action is not applied)action
- the actionpublic <U> U searchValues(long parallelismThreshold, Function<? super V,? extends U> searchFunction)
U
- the return type of the search functionparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelsearchFunction
- a function returning a non-null result on success, else nullpublic V reduceValues(long parallelismThreshold, BiFunction<? super V,? super V,? extends V> reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelreducer
- a commutative associative combining functionpublic <U> U reduceValues(long parallelismThreshold, Function<? super V,? extends U> transformer, BiFunction<? super U,? super U,? extends U> reducer)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case it is not combined)reducer
- a commutative associative combining functionpublic double reduceValuesToDouble(long parallelismThreshold, ToDoubleFunction<? super V> transformer, double basis, DoubleBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic long reduceValuesToLong(long parallelismThreshold, ToLongFunction<? super V> transformer, long basis, LongBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic int reduceValuesToInt(long parallelismThreshold, ToIntFunction<? super V> transformer, int basis, IntBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic void forEachEntry(long parallelismThreshold, Consumer<? super Map.Entry<K,V>> action)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelaction
- the actionpublic <U> void forEachEntry(long parallelismThreshold, Function<Map.Entry<K,V>,? extends U> transformer, Consumer<? super U> action)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case the action is not applied)action
- the actionpublic <U> U searchEntries(long parallelismThreshold, Function<Map.Entry<K,V>,? extends U> searchFunction)
U
- the return type of the search functionparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelsearchFunction
- a function returning a non-null result on success, else nullpublic Map.Entry<K,V> reduceEntries(long parallelismThreshold, BiFunction<Map.Entry<K,V>,Map.Entry<K,V>,? extends Map.Entry<K,V>> reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in parallelreducer
- a commutative associative combining functionpublic <U> U reduceEntries(long parallelismThreshold, Function<Map.Entry<K,V>,? extends U> transformer, BiFunction<? super U,? super U,? extends U> reducer)
U
- the return type of the transformerparallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an element, or null if there is no transformation (in which case it is not combined)reducer
- a commutative associative combining functionpublic double reduceEntriesToDouble(long parallelismThreshold, ToDoubleFunction<Map.Entry<K,V>> transformer, double basis, DoubleBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic long reduceEntriesToLong(long parallelismThreshold, ToLongFunction<Map.Entry<K,V>> transformer, long basis, LongBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining functionpublic int reduceEntriesToInt(long parallelismThreshold, ToIntFunction<Map.Entry<K,V>> transformer, int basis, IntBinaryOperator reducer)
parallelismThreshold
- the (estimated) number of elements needed for this operation to be executed in paralleltransformer
- a function returning the transformation for an elementbasis
- the identity (initial default value) for the reductionreducer
- a commutative associative combining function
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