package java.util.concurrent;
import java.util.Map;
public interface ConcurrentMap<K, V> extends Map<K, V> {
/**
* If the specified key is not already associated
* with a value, associate it with the given value.
* This is equivalent to
* <pre>
* if (!map.containsKey(key))
* return map.put(key, value);
* else
* return map.get(key);</pre>
* except that the action is performed atomically.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with the specified key, or
* <tt>null</tt> if there was no mapping for the key.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with the key,
* if the implementation supports null values.)
* @throws UnsupportedOperationException if the <tt>put</tt> operation
* is not supported by this map
* @throws ClassCastException if the class of the specified key or value
* prevents it from being stored in this map
* @throws NullPointerException if the specified key or value is null,
* and this map does not permit null keys or values
* @throws IllegalArgumentException if some property of the specified key
* or value prevents it from being stored in this map
*
*/
V putIfAbsent(K key, V value);
/**
* Removes the entry for a key only if currently mapped to a given value.
* This is equivalent to
* <pre>
* if (map.containsKey(key) && map.get(key).equals(value)) {
* map.remove(key);
* return true;
* } else return false;</pre>
* except that the action is performed atomically.
*
* @param key key with which the specified value is associated
* @param value value expected to be associated with the specified key
* @return <tt>true</tt> if the value was removed
* @throws UnsupportedOperationException if the <tt>remove</tt> operation
* is not supported by this map
* @throws ClassCastException if the key or value is of an inappropriate
* type for this map (optional)
* @throws NullPointerException if the specified key or value is null,
* and this map does not permit null keys or values (optional)
*/
boolean remove(Object key, Object value);
/**
* Replaces the entry for a key only if currently mapped to a given value.
* This is equivalent to
* <pre>
* if (map.containsKey(key) && map.get(key).equals(oldValue)) {
* map.put(key, newValue);
* return true;
* } else return false;</pre>
* except that the action is performed atomically.
*
* @param key key with which the specified value is associated
* @param oldValue value expected to be associated with the specified key
* @param newValue value to be associated with the specified key
* @return <tt>true</tt> if the value was replaced
* @throws UnsupportedOperationException if the <tt>put</tt> operation
* is not supported by this map
* @throws ClassCastException if the class of a specified key or value
* prevents it from being stored in this map
* @throws NullPointerException if a specified key or value is null,
* and this map does not permit null keys or values
* @throws IllegalArgumentException if some property of a specified key
* or value prevents it from being stored in this map
*/
boolean replace(K key, V oldValue, V newValue);
/**
* Replaces the entry for a key only if currently mapped to some value.
* This is equivalent to
* <pre>
* if (map.containsKey(key)) {
* return map.put(key, value);
* } else return null;</pre>
* except that the action is performed atomically.
*
* @param key key with which the specified value is associated
* @param value value to be associated with the specified key
* @return the previous value associated with the specified key, or
* <tt>null</tt> if there was no mapping for the key.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with the key,
* if the implementation supports null values.)
* @throws UnsupportedOperationException if the <tt>put</tt> operation
* is not supported by this map
* @throws ClassCastException if the class of the specified key or value
* prevents it from being stored in this map
* @throws NullPointerException if the specified key or value is null,
* and this map does not permit null keys or values
* @throws IllegalArgumentException if some property of the specified key
* or value prevents it from being stored in this map
*/
V replace(K key, V value);
}