Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Superinterfaces:

Map<K,V>

All Known Subinterfaces:

ConcurrentNavigableMap<K,V>

All Known Implementing Classes:

ConcurrentHashMap, ConcurrentSkipListMap

public interface ConcurrentMap<K,V>
extends Map<K,V>

Since:

1.5

• Nested Class Summary

  • Nested classes/interfaces inherited from interface java.util.Map

    Map.Entry<K,V>

• Method Summary

  Methods

  Modifier and Type	Method and Description
  V	putIfAbsent (K key, V value) If the specified key is not already associated with a value, associate it with the given value.
  boolean	remove (Object key, Object value) Removes the entry for a key only if currently mapped to a given value.
  V	replace (K key, V value) Replaces the entry for a key only if currently mapped to some value.
  boolean	replace (K key, V oldValue, V newValue) Replaces the entry for a key only if currently mapped to a given value.

  • Methods inherited from interface java.util.Map

    clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

• Method Detail

  • putIfAbsent

    V putIfAbsent(K key,
     V value)

    If the specified key is not already associated with a value, associate it with the given value. This is equivalent to

     if (!map.containsKey(key))
     return map.put(key, value);
     else
     return map.get(key);

    except that the action is performed atomically.

    Parameters:

    key - key with which the specified value is to be associated

    value - value to be associated with the specified key

    Returns:

    the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)

    Throws:

    UnsupportedOperationException - if the put operation is not supported by this map

    ClassCastException - if the class of the specified key or value prevents it from being stored in this map

    NullPointerException - if the specified key or value is null, and this map does not permit null keys or values

    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map

  • remove

    boolean remove(Object key,
     Object value)

    Removes the entry for a key only if currently mapped to a given value. This is equivalent to

     if (map.containsKey(key) && map.get(key).equals(value)) {
     map.remove(key);
     return true;
     } else return false;

    except that the action is performed atomically.

    Parameters:

    key - key with which the specified value is associated

    value - value expected to be associated with the specified key

    Returns:

    true if the value was removed

    Throws:

    UnsupportedOperationException - if the remove operation is not supported by this map

    ClassCastException - if the key or value is of an inappropriate type for this map (optional)

    NullPointerException - if the specified key or value is null, and this map does not permit null keys or values (optional)

  • replace

    boolean replace(K key,
     V oldValue,
     V newValue)

    Replaces the entry for a key only if currently mapped to a given value. This is equivalent to

     if (map.containsKey(key) && map.get(key).equals(oldValue)) {
     map.put(key, newValue);
     return true;
     } else return false;

    except that the action is performed atomically.

    Parameters:

    key - key with which the specified value is associated

    oldValue - value expected to be associated with the specified key

    newValue - value to be associated with the specified key

    Returns:

    true if the value was replaced

    Throws:

    UnsupportedOperationException - if the put operation is not supported by this map

    ClassCastException - if the class of a specified key or value prevents it from being stored in this map

    NullPointerException - if a specified key or value is null, and this map does not permit null keys or values

    IllegalArgumentException - if some property of a specified key or value prevents it from being stored in this map

  • replace

    V replace(K key,
     V value)

    Replaces the entry for a key only if currently mapped to some value. This is equivalent to

     if (map.containsKey(key)) {
     return map.put(key, value);
     } else return null;

    except that the action is performed atomically.

    Parameters:

    key - key with which the specified value is associated

    value - value to be associated with the specified key

    Returns:

    the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)

    Throws:

    UnsupportedOperationException - if the put operation is not supported by this map

    ClassCastException - if the class of the specified key or value prevents it from being stored in this map

    NullPointerException - if the specified key or value is null, and this map does not permit null keys or values

    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map