org.apache.commons.collections.map

Class LazySortedMap

public class LazySortedMap extends LazyMap implements SortedMap

Decorates another SortedMap to create objects in the map on demand.

When the LazySortedMap 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 factory = new Factory() {
     public Object create() {
         return new Date();
     }
 }
 SortedMap lazy = Lazy.sortedMap(new HashMap(), factory);
 Object obj = lazy.get("NOW");
 
After the above code is executed, obj will contain 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 java.util.Collections#synchronizedSortedMap. This class may throw exceptions when accessed by concurrent threads without synchronization.

This class is Serializable from Commons Collections 3.1.

Since: Commons Collections 3.0

Version: $Revision: 348007 $ $Date: 2005-11-21 22:52:57 +0000 (Mon, 21 Nov 2005) $

Author: Stephen Colebourne Paul Jack

Constructor Summary
protected LazySortedMap(SortedMap map, Factory factory)
Constructor that wraps (not copies).
protected LazySortedMap(SortedMap map, Transformer factory)
Constructor that wraps (not copies).
Method Summary
Comparatorcomparator()
static SortedMapdecorate(SortedMap map, Factory factory)
Factory method to create a lazily instantiated sorted map.
static SortedMapdecorate(SortedMap map, Transformer factory)
Factory method to create a lazily instantiated sorted map.
ObjectfirstKey()
protected SortedMapgetSortedMap()
Gets the map being decorated.
SortedMapheadMap(Object toKey)
ObjectlastKey()
SortedMapsubMap(Object fromKey, Object toKey)
SortedMaptailMap(Object fromKey)

Constructor Detail

LazySortedMap

protected LazySortedMap(SortedMap map, Factory 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: IllegalArgumentException if map or factory is null

LazySortedMap

protected LazySortedMap(SortedMap map, Transformer 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: IllegalArgumentException if map or factory is null

Method Detail

comparator

public Comparator comparator()

decorate

public static SortedMap decorate(SortedMap map, Factory factory)
Factory method to create a lazily instantiated sorted map.

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 SortedMap decorate(SortedMap map, Transformer factory)
Factory method to create a lazily instantiated sorted map.

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

firstKey

public Object firstKey()

getSortedMap

protected SortedMap getSortedMap()
Gets the map being decorated.

Returns: the decorated map

headMap

public SortedMap headMap(Object toKey)

lastKey

public Object lastKey()

subMap

public SortedMap subMap(Object fromKey, Object toKey)

tailMap

public SortedMap tailMap(Object fromKey)
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