Package org.apache.commons.collections.map

Class DefaultedMap

java.lang.Object
org.apache.commons.collections.map.AbstractMapDecorator
org.apache.commons.collections.map.DefaultedMap
All Implemented Interfaces:
Serializable, Map
@Deprecated(since="2021-04-30") public class DefaultedMap extends AbstractMapDecorator implements Map, Serializable
Deprecated.
Apache Commons Collections version 3.x is being deprecated from AEMaaCS. The upgraded version 4.4 of Commons Collections is already included as replacement. Customers are advised to upgrade to this version of the library. Please note: the package name was changed to org.apache.commons.collections4. Further note that there are AEM APIs currently exposing the old collections classes; these will be updated in upcoming releases.
Decorates another Map returning a default value if the map does not contain the requested key.

When the get(Object) method is called with a key that does not exist in the map, this map will return the default value specified in the constructor/factory. Only the get method is altered, so the Map.containsKey(Object) can be used to determine if a key really is in the map or not.

The defaulted value is not added to the map. Compare this behaviour with LazyMap, which does add the value to the map (via a Transformer).

For instance: 

  Map map = new DefaultedMap("NULL");
  Object obj = map.get("Surname");
  // obj == "NULL"
After the above code is executed the map is still empty.

Note that DefaultedMap 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.

Since:
Commons Collections 3.2
See Also:

  • Constructor Details

    • DefaultedMap

      public DefaultedMap(Object defaultValue)
      Deprecated.
      Constructs a new empty DefaultedMap that decorates a HashMap.

      The object passed in will be returned by the map whenever an unknown key is requested.

      Parameters:
      defaultValue - the default value to return when the key is not found

  • Method Details

    • decorate

      public static Map decorate(Map map, Object defaultValue)
      Deprecated.
      Factory method to create a defaulting map.

      The value specified is returned when a missing key is found.

      Parameters:
      map - the map to decorate, must not be null
      defaultValue - the default value to return when the key is not found
      Throws:
      IllegalArgumentException - if map is null

    • decorate

      public static Map decorate(Map map, Factory factory)
      Deprecated.
      Factory method to create a defaulting map.

      The factory specified is called when a missing key is found. The result will be returned as the result of the map get(key) method.

      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Throws:
      IllegalArgumentException - if map or factory is null

    • decorate

      public static Map decorate(Map map, Transformer factory)
      Deprecated.
      Factory method to create a defaulting map.

      The transformer specified is called when a missing key is found. The key is passed to the transformer as the input, and the result will be returned as the result of the map get(key) method.

      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Throws:
      IllegalArgumentException - if map or factory is null

    • get

      public Object get(Object key)
      Deprecated.
      Specified by:
      get in interface Map
      Overrides:
      get in class AbstractMapDecorator