Class LazySortedMap<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>, SortedMap<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>

public class LazySortedMap<K,V> extends LazyMap<K,V> implements SortedMap<K,V>
Decorates another SortedMap to create objects in the map on demand.

When the LazyMap.get(Object) method is called with a key that does not exist in the map, the factory is used to create the object. The created object will be added to the map using the requested key.

For instance:

 Factory<Date> factory = new Factory<Date>() {
     public Date create() {
         return new Date();
     }
 }
 SortedMap<String, Date> lazy =
     LazySortedMap.lazySortedMap(new HashMap<String, Date>(), factory);
 Date date = lazy.get("NOW");
 

After the above code is executed, date will refer to a new Date instance. Furthermore, that Date instance is mapped to the "NOW" key in the map.

Note that LazySortedMap 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.synchronizedSortedMap(java.util.SortedMap<K, V>). 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:
  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serialization version
      See Also:
  • Constructor Details

    • LazySortedMap

      protected LazySortedMap(SortedMap<K,V> map, Factory<? extends V> factory)
      Constructor that wraps (not copies).
      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Throws:
      NullPointerException - if map or factory is null
    • LazySortedMap

      protected LazySortedMap(SortedMap<K,V> map, Transformer<? super K,? extends V> factory)
      Constructor that wraps (not copies).
      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Throws:
      NullPointerException - if map or factory is null
  • Method Details

    • lazySortedMap

      public static <K, V> LazySortedMap<K,V> lazySortedMap(SortedMap<K,V> map, Factory<? extends V> factory)
      Factory method to create a lazily instantiated sorted map.
      Type Parameters:
      K - the key type
      V - the value type
      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Returns:
      a new lazy sorted map
      Throws:
      NullPointerException - if map or factory is null
      Since:
      4.0
    • lazySortedMap

      public static <K, V> LazySortedMap<K,V> lazySortedMap(SortedMap<K,V> map, Transformer<? super K,? extends V> factory)
      Factory method to create a lazily instantiated sorted map.
      Type Parameters:
      K - the key type
      V - the value type
      Parameters:
      map - the map to decorate, must not be null
      factory - the factory to use, must not be null
      Returns:
      a new lazy sorted map
      Throws:
      NullPointerException - if map or factory is null
      Since:
      4.0
    • getSortedMap

      protected SortedMap<K,V> getSortedMap()
      Gets the map being decorated.
      Returns:
      the decorated map
    • firstKey

      public K firstKey()
      Specified by:
      firstKey in interface SortedMap<K,V>
    • lastKey

      public K lastKey()
      Specified by:
      lastKey in interface SortedMap<K,V>
    • comparator

      public Comparator<? super K> comparator()
      Specified by:
      comparator in interface SortedMap<K,V>
    • subMap

      public SortedMap<K,V> subMap(K fromKey, K toKey)
      Specified by:
      subMap in interface SortedMap<K,V>
    • headMap

      public SortedMap<K,V> headMap(K toKey)
      Specified by:
      headMap in interface SortedMap<K,V>
    • tailMap

      public SortedMap<K,V> tailMap(K fromKey)
      Specified by:
      tailMap in interface SortedMap<K,V>