| /* |
| * Written by Doug Lea with assistance from members of JCP JSR-166 |
| * Expert Group and released to the public domain, as explained at |
| * http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| package java.util.concurrent; |
| |
| import java.util.Map; |
| |
| // BEGIN android-note |
| // removed link to collections framework docs |
| // END android-note |
| |
| /** |
| * A {@link java.util.Map} providing additional atomic |
| * {@code putIfAbsent}, {@code remove}, and {@code replace} methods. |
| * |
| * <p>Memory consistency effects: As with other concurrent |
| * collections, actions in a thread prior to placing an object into a |
| * {@code ConcurrentMap} as a key or value |
| * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> |
| * actions subsequent to the access or removal of that object from |
| * the {@code ConcurrentMap} in another thread. |
| * |
| * @since 1.5 |
| * @author Doug Lea |
| * @param <K> the type of keys maintained by this map |
| * @param <V> the type of mapped values |
| */ |
| 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> {@code |
| * 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 |
| * {@code null} if there was no mapping for the key. |
| * (A {@code null} return can also indicate that the map |
| * previously associated {@code null} with the key, |
| * if the implementation supports null values.) |
| * @throws UnsupportedOperationException if the {@code put} 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> {@code |
| * 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 {@code true} if the value was removed |
| * @throws UnsupportedOperationException if the {@code remove} operation |
| * is not supported by this map |
| * @throws ClassCastException if the key or value is of an inappropriate |
| * type for this map |
| * (<a href="../Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if the specified key or value is null, |
| * and this map does not permit null keys or values |
| * (<a href="../Collection.html#optional-restrictions">optional</a>) |
| */ |
| 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> {@code |
| * 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 {@code true} if the value was replaced |
| * @throws UnsupportedOperationException if the {@code put} 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> {@code |
| * 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 |
| * {@code null} if there was no mapping for the key. |
| * (A {@code null} return can also indicate that the map |
| * previously associated {@code null} with the key, |
| * if the implementation supports null values.) |
| * @throws UnsupportedOperationException if the {@code put} 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); |
| } |
