Class AtomicLongMap<K>

java.lang.Object
com.google.common.util.concurrent.AtomicLongMap<K>
All Implemented Interfaces:
Serializable
@GwtCompatible public final class AtomicLongMap<K> extends Object implements Serializable
A map containing long values that can be atomically updated. While writes to a traditional Map rely on put(K, V), the typical mechanism for writing to this map is addAndGet(K, long), which adds a long to the value currently associated with K. If a key has not yet been associated with a value, its implicit value is zero.

Most methods in this class treat absent values and zero values identically, as individually documented. Exceptions to this are containsKey(java.lang.Object), size(), isEmpty(), asMap, and toString().

Instances of this class may be used by multiple threads concurrently. All operations are atomic unless otherwise noted.

Instances of this class are serializable if the keys are serializable.

Note: If your values are always positive and less than 2^31, you may wish to use a Multiset such as ConcurrentHashMultiset instead.

Warning: Unlike Multiset, entries whose values are zero are not automatically removed from the map. Instead they must be removed manually with removeAllZeros().

Since:
11.0
Author:
Charles Fry
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    addAndGet(K key, long delta)
    Adds delta to the value currently associated with key, and returns the new value.
    Map<K,Long>
    asMap()
    Returns a live, read-only view of the map backing this AtomicLongMap.
    void
    clear()
    Removes all of the mappings from this map.
    boolean
    containsKey(Object key)
    Returns true if this map contains a mapping for the specified key.
    static <K> AtomicLongMap<K>
    create()
    Creates an AtomicLongMap.
    static <K> AtomicLongMap<K>
    create(Map<? extends K, ? extends Long> m)
    Creates an AtomicLongMap with the same mappings as the specified Map.
    long
    decrementAndGet(K key)
    Decrements by one the value currently associated with key, and returns the new value.
    long
    get(K key)
    Returns the value associated with key, or zero if there is no value associated with key.
    long
    getAndAdd(K key, long delta)
    Adds delta to the value currently associated with key, and returns the old value.
    long
    getAndDecrement(K key)
    Decrements by one the value currently associated with key, and returns the old value.
    long
    getAndIncrement(K key)
    Increments by one the value currently associated with key, and returns the old value.
    long
    incrementAndGet(K key)
    Increments by one the value currently associated with key, and returns the new value.
    boolean
    isEmpty()
    Returns true if this map contains no key-value mappings.
    long
    put(K key, long newValue)
    Associates newValue with key in this map, and returns the value previously associated with key, or zero if there was no such value.
    void
    putAll(Map<? extends K, ? extends Long> m)
    Copies all of the mappings from the specified map to this map.
    long
    remove(K key)
    Removes and returns the value associated with key.
    void
    removeAllZeros()
    Removes all mappings from this map whose values are zero.
    boolean
    removeIfZero(K key)
    Atomically remove key from the map iff its associated value is 0.
    int
    size()
    Returns the number of key-value mappings in this map.
    long
    sum()
    Returns the sum of all values in this map.
    String
    toString()
     

    Methods inherited from class java.lang.Object

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

  • Method Details

    • create

      public static <K> AtomicLongMap<K> create()
      Creates an AtomicLongMap.

    • create

      public static <K> AtomicLongMap<K> create(Map<? extends K, ? extends Long> m)
      Creates an AtomicLongMap with the same mappings as the specified Map.

    • get

      public long get(K key)
      Returns the value associated with key, or zero if there is no value associated with key.

    • incrementAndGet

      @CanIgnoreReturnValue public long incrementAndGet(K key)
      Increments by one the value currently associated with key, and returns the new value.

    • decrementAndGet

      @CanIgnoreReturnValue public long decrementAndGet(K key)
      Decrements by one the value currently associated with key, and returns the new value.

    • addAndGet

      @CanIgnoreReturnValue public long addAndGet(K key, long delta)
      Adds delta to the value currently associated with key, and returns the new value.

    • getAndIncrement

      @CanIgnoreReturnValue public long getAndIncrement(K key)
      Increments by one the value currently associated with key, and returns the old value.

    • getAndDecrement

      @CanIgnoreReturnValue public long getAndDecrement(K key)
      Decrements by one the value currently associated with key, and returns the old value.

    • getAndAdd

      @CanIgnoreReturnValue public long getAndAdd(K key, long delta)
      Adds delta to the value currently associated with key, and returns the old value.

    • put

      @CanIgnoreReturnValue public long put(K key, long newValue)
      Associates newValue with key in this map, and returns the value previously associated with key, or zero if there was no such value.

    • putAll

      public void putAll(Map<? extends K, ? extends Long> m)
      Copies all of the mappings from the specified map to this map. The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

    • remove

      @CanIgnoreReturnValue public long remove(K key)
      Removes and returns the value associated with key. If key is not in the map, this method has no effect and returns zero.

    • removeIfZero

      @CanIgnoreReturnValue public boolean removeIfZero(K key)
      Atomically remove key from the map iff its associated value is 0.
      Since:
      20.0

    • removeAllZeros

      public void removeAllZeros()
      Removes all mappings from this map whose values are zero.

      This method is not atomic: the map may be visible in intermediate states, where some of the zero values have been removed and others have not.

    • sum

      public long sum()
      Returns the sum of all values in this map.

      This method is not atomic: the sum may or may not include other concurrent operations.

    • asMap

      public Map<K,Long> asMap()
      Returns a live, read-only view of the map backing this AtomicLongMap.

    • containsKey

      public boolean containsKey(Object key)
      Returns true if this map contains a mapping for the specified key.

    • size

      public int size()
      Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

    • isEmpty

      public boolean isEmpty()
      Returns true if this map contains no key-value mappings.

    • clear

      public void clear()
      Removes all of the mappings from this map. The map will be empty after this call returns.

      This method is not atomic: the map may not be empty after returning if there were concurrent writes.

    • toString

      public String toString()
      Overrides:
      toString in class Object