Package org.apache.commons.collections4.map

Class PredicatedMap<K,​V>

  • Type Parameters:
    K - the type of the keys in this map
    V - the type of the values in this map
    All Implemented Interfaces:
    Serializable, Map<K,​V>, Get<K,​V>, IterableGet<K,​V>, IterableMap<K,​V>, Put<K,​V>
    Direct Known Subclasses:
    PredicatedSortedMap
    public class PredicatedMap<K,​V>
extends AbstractMapDecorator<K,​V>
implements Serializable
    Decorates another Map to validate that additions match a specified predicate.

    This map exists to provide validation for the decorated map. It is normally created to decorate an empty map. If an object cannot be added to the map, an IllegalArgumentException is thrown.

    One usage would be to ensure that no null keys are added to the map. 

    Map map = PredicatedSet.decorate(new HashMap(), NotNullPredicate.INSTANCE, null);

    Note that PredicatedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

    This class is Serializable from Commons Collections 3.1.

    Since:
    3.0
    See Also:
    Serialized Form

    • Field Detail

      • keyPredicate

        protected final Predicate<? super K> keyPredicate
        The key predicate to use

      • valuePredicate

        protected final Predicate<? super V> valuePredicate
        The value predicate to use

    • Constructor Detail

      • PredicatedMap

        protected PredicatedMap​(Map<K,​V> map,
                        Predicate<? super K> keyPredicate,
                        Predicate<? super V> valuePredicate)
        Constructor that wraps (not copies).
        Parameters:
        map - the map to decorate, must not be null
        keyPredicate - the predicate to validate the keys, null means no check
        valuePredicate - the predicate to validate to values, null means no check
        Throws:
        NullPointerException - if the map is null

    • Method Detail

      • predicatedMap

        public static <K,​V> PredicatedMap<K,​V> predicatedMap​(Map<K,​V> map,
                                                                 Predicate<? super K> keyPredicate,
                                                                 Predicate<? super V> valuePredicate)
        Factory method to create a predicated (validating) map.

        If there are any elements already in the list being decorated, they are validated.

        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        map - the map to decorate, must not be null
        keyPredicate - the predicate to validate the keys, null means no check
        valuePredicate - the predicate to validate to values, null means no check
        Returns:
        a new predicated map
        Throws:
        NullPointerException - if the map is null
        Since:
        4.0

      • validate

        protected void validate​(K key,
                        V value)
        Validates a key value pair.
        Parameters:
        key - the key to validate
        value - the value to validate
        Throws:
        IllegalArgumentException - if invalid

      • checkSetValue

        protected V checkSetValue​(V value)
        Override to validate an object set into the map via setValue.
        Parameters:
        value - the value to validate
        Returns:
        the value itself
        Throws:
        IllegalArgumentException - if invalid
        Since:
        3.1

      • isSetValueChecking

        protected boolean isSetValueChecking()
        Override to only return true when there is a value transformer.
        Returns:
        true if a value predicate is in use
        Since:
        3.1

      • put

        public V put​(K key,
             V value)
        Description copied from interface: Put
        Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.
        Specified by:
        put in interface Map<K,​V>
        Specified by:
        put in interface Put<K,​V>
        Overrides:
        put in class AbstractMapDecorator<K,​V>
        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 key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)
        See Also:
        Map.put(Object, Object)