jsr166e

Class LongAdderTable<K>

java.lang.Object

jsr166e.LongAdderTable<K>

All Implemented Interfaces:

Serializable

public class LongAdderTable<K>
extends Object
implements Serializable

A keyed table of adders, that may be useful in computing frequency counts and histograms, or may be used as a form of multiset. A LongAdder is associated with each key. Keys are added to the table implicitly upon any attempt to update, or may be added explicitly using method install(K).

jsr166e note: This class is targeted to be placed in java.util.concurrent.atomic.

Since:

1.8

Author:

Doug Lea

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LongAdderTable() Creates a new empty table.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(K key, long x) Adds the given value to the sum associated with the given key.
void	decrement(K key) Decrements the sum associated with the given key.
Set<Map.Entry<K,LongAdder>>	entrySet() Returns the current set of key-value mappings.
void	increment(K key) Increments the sum associated with the given key.
LongAdder	install(K key) If the given key does not already exist in the table, inserts the key with initial sum of zero; in either case returning the adder associated with this key.
Set<K>	keySet() Returns the current set of keys.
void	remove(K key) Removes the given key from the table.
void	removeAll() Removes all keys from the table.
void	reset(K key) Resets the sum associated with the given key to zero if the key exists in the table.
void	resetAll() Resets the sum associated with each key to zero.
long	sum(K key) Returns the sum associated with the given key, or zero if the key does not currently exist in the table.
long	sumAll() Returns the sum totalled across all keys.
long	sumThenReset(K key) Resets the sum associated with the given key to zero if the key exists in the table.
long	sumThenResetAll() Totals, then resets, the sums associated with all keys.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LongAdderTable

public LongAdderTable()

Creates a new empty table.

Method Detail

install

public LongAdder install(K key)

If the given key does not already exist in the table, inserts the key with initial sum of zero; in either case returning the adder associated with this key.

Parameters:

key - the key

Returns:

the adder associated with the key

add

public void add(K key,
       long x)

Adds the given value to the sum associated with the given key. If the key does not already exist in the table, it is inserted.

Parameters:

key - the key

x - the value to add

increment

public void increment(K key)

Increments the sum associated with the given key. If the key does not already exist in the table, it is inserted.

Parameters:

key - the key

decrement

public void decrement(K key)

Decrements the sum associated with the given key. If the key does not already exist in the table, it is inserted.

Parameters:

key - the key

sum

public long sum(K key)

Returns the sum associated with the given key, or zero if the key does not currently exist in the table.

Parameters:

key - the key

Returns:

the sum associated with the key, or zero if the key is not in the table

reset

public void reset(K key)

Resets the sum associated with the given key to zero if the key exists in the table. This method does NOT add or remove the key from the table (see remove(K)).

Parameters:

key - the key

sumThenReset

public long sumThenReset(K key)

Resets the sum associated with the given key to zero if the key exists in the table. This method does NOT add or remove the key from the table (see remove(K)).

Parameters:

key - the key

Returns:

the previous sum, or zero if the key is not in the table

sumAll

public long sumAll()

Returns the sum totalled across all keys.

Returns:

the sum totalled across all keys

resetAll

public void resetAll()

Resets the sum associated with each key to zero.

sumThenResetAll

public long sumThenResetAll()

Totals, then resets, the sums associated with all keys.

Returns:

the sum totalled across all keys

remove

public void remove(K key)

Removes the given key from the table.

Parameters:

key - the key

removeAll

public void removeAll()

Removes all keys from the table.

keySet

public Set<K> keySet()

Returns the current set of keys.

Returns:

the current set of keys

entrySet

public Set<Map.Entry<K,LongAdder>> entrySet()

Returns the current set of key-value mappings.

Returns:

the current set of key-value mappings