Overview  Package   Class  Use  Tree  Deprecated  Index  Help 
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD

org.apache.commons.collections.map
Class MultiKeyMap

java.lang.Object
  extended by org.apache.commons.collections.map.MultiKeyMap
All Implemented Interfaces:
java.io.Serializable, java.util.Map, IterableMap
public class MultiKeyMap
extends java.lang.Object
implements IterableMap, java.io.Serializable

A Map implementation that uses multiple keys to map the value.

This class is the most efficient way to uses multiple keys to map to a value. The best way to use this class is via the additional map-style methods. These provide get, containsKey, put and remove for individual keys which operate without extra object creation.

The additional methods are the main interface of this map. As such, you will not normally hold this map in a variable of type Map.

The normal map methods take in and return a MultiKey. If you try to use put() with any other object type a ClassCastException is thrown. If you try to use null as the key in put() a NullPointerException is thrown.

This map is implemented as a decorator of a AbstractHashedMap which enables extra behaviour to be added easily.

Note that IdentityMap and ReferenceIdentityMap are unsuitable for use as the key comparison would work on the whole MultiKey, not the elements within.

As an example, consider a least recently used cache that uses a String airline code and a Locale to lookup the airline's name: 

 private MultiKeyMap cache = MultiKeyMap.decorate(new LRUMap(50));
 
 public String getAirlineName(String code, String locale) {
   String name = (String) cache.get(code, locale);
   if (name == null) {
     name = getAirlineNameFromDB(code, locale);
     cache.put(code, locale, name);
   }
   return name;
 }

Note that MultiKeyMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. This class may throw exceptions when accessed by concurrent threads without synchronization.

Since:
Commons Collections 3.1
Version:
$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
Author:
Stephen Colebourne
See Also:
Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from interface java.util.Map
java.util.Map.Entry
 
Field Summary
protected  AbstractHashedMap map
          The decorated map
 
Constructor Summary
  MultiKeyMap()
          Constructs a new MultiKeyMap that decorates a HashedMap.
protected MultiKeyMap(AbstractHashedMap map)
          Constructor that decorates the specified map and is called from decorate(AbstractHashedMap).
 
Method Summary
protected  void checkKey(java.lang.Object key)
          Check to ensure that input keys are valid MultiKey objects.
 void clear()
           
 java.lang.Object clone()
          Clones the map without cloning the keys or values.
 boolean containsKey(java.lang.Object key)
           
 boolean containsKey(java.lang.Object key1, java.lang.Object key2)
          Checks whether the map contains the specified multi-key.
 boolean containsKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Checks whether the map contains the specified multi-key.
 boolean containsKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Checks whether the map contains the specified multi-key.
 boolean containsKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)
          Checks whether the map contains the specified multi-key.
 boolean containsValue(java.lang.Object value)
           
static MultiKeyMap decorate(AbstractHashedMap map)
          Decorates the specified map to add the MultiKeyMap API and fast query.
 java.util.Set entrySet()
           
 boolean equals(java.lang.Object obj)
           
 java.lang.Object get(java.lang.Object key)
           
 java.lang.Object get(java.lang.Object key1, java.lang.Object key2)
          Gets the value mapped to the specified multi-key.
 java.lang.Object get(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Gets the value mapped to the specified multi-key.
 java.lang.Object get(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Gets the value mapped to the specified multi-key.
 java.lang.Object get(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)
          Gets the value mapped to the specified multi-key.
protected  int hash(java.lang.Object key1, java.lang.Object key2)
          Gets the hash code for the specified multi-key.
protected  int hash(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Gets the hash code for the specified multi-key.
protected  int hash(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Gets the hash code for the specified multi-key.
protected  int hash(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)
          Gets the hash code for the specified multi-key.
 int hashCode()
           
 boolean isEmpty()
           
protected  boolean isEqualKey(AbstractHashedMap.HashEntry entry, java.lang.Object key1, java.lang.Object key2)
          Is the key equal to the combined key.
protected  boolean isEqualKey(AbstractHashedMap.HashEntry entry, java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Is the key equal to the combined key.
protected  boolean isEqualKey(AbstractHashedMap.HashEntry entry, java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Is the key equal to the combined key.
protected  boolean isEqualKey(AbstractHashedMap.HashEntry entry, java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)
          Is the key equal to the combined key.
 java.util.Set keySet()
           
 MapIterator mapIterator()
          Obtains a MapIterator over the map.
 java.lang.Object put(java.lang.Object key, java.lang.Object value)
          Puts the key and value into the map, where the key must be a non-null MultiKey object.
 java.lang.Object put(java.lang.Object key1, java.lang.Object key2, java.lang.Object value)
          Stores the value against the specified multi-key.
 java.lang.Object put(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object value)
          Stores the value against the specified multi-key.
 java.lang.Object put(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object value)
          Stores the value against the specified multi-key.
 java.lang.Object put(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5, java.lang.Object value)
          Stores the value against the specified multi-key.
 void putAll(java.util.Map mapToCopy)
          Copies all of the keys and values from the specified map to this map.
 java.lang.Object remove(java.lang.Object key)
           
 java.lang.Object remove(java.lang.Object key1, java.lang.Object key2)
          Removes the specified multi-key from this map.
 java.lang.Object remove(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Removes the specified multi-key from this map.
 java.lang.Object remove(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Removes the specified multi-key from this map.
 java.lang.Object remove(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)
          Removes the specified multi-key from this map.
 boolean removeAll(java.lang.Object key1)
          Removes all mappings where the first key is that specified.
 boolean removeAll(java.lang.Object key1, java.lang.Object key2)
          Removes all mappings where the first two keys are those specified.
 boolean removeAll(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)
          Removes all mappings where the first three keys are those specified.
 boolean removeAll(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)
          Removes all mappings where the first four keys are those specified.
 int size()
           
 java.lang.String toString()
           
 java.util.Collection values()
           
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

map

protected final AbstractHashedMap map
The decorated map

Constructor Detail

MultiKeyMap

public MultiKeyMap()
Constructs a new MultiKeyMap that decorates a HashedMap.

MultiKeyMap

protected MultiKeyMap(AbstractHashedMap map)
Constructor that decorates the specified map and is called from decorate(AbstractHashedMap). The map must not be null and should be empty or only contain valid keys. This constructor performs no validation.

Parameters:
map - the map to decorate
Method Detail

decorate

public static MultiKeyMap decorate(AbstractHashedMap map)
Decorates the specified map to add the MultiKeyMap API and fast query. The map must not be null and must be empty.

Parameters:
map - the map to decorate, not null
Throws:
java.lang.IllegalArgumentException - if the map is null or not empty

get

public java.lang.Object get(java.lang.Object key1,
                            java.lang.Object key2)
Gets the value mapped to the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
Returns:
the mapped value, null if no match

containsKey

public boolean containsKey(java.lang.Object key1,
                           java.lang.Object key2)
Checks whether the map contains the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
Returns:
true if the map contains the key

put

public java.lang.Object put(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object value)
Stores the value against the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
value - the value to store
Returns:
the value previously mapped to this combined key, null if none

remove

public java.lang.Object remove(java.lang.Object key1,
                               java.lang.Object key2)
Removes the specified multi-key from this map.

Parameters:
key1 - the first key
key2 - the second key
Returns:
the value mapped to the removed key, null if key not in map

hash

protected int hash(java.lang.Object key1,
                   java.lang.Object key2)
Gets the hash code for the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
Returns:
the hash code

isEqualKey

protected boolean isEqualKey(AbstractHashedMap.HashEntry entry,
                             java.lang.Object key1,
                             java.lang.Object key2)
Is the key equal to the combined key.

Parameters:
entry - the entry to compare to
key1 - the first key
key2 - the second key
Returns:
true if the key matches

get

public java.lang.Object get(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3)
Gets the value mapped to the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
the mapped value, null if no match

containsKey

public boolean containsKey(java.lang.Object key1,
                           java.lang.Object key2,
                           java.lang.Object key3)
Checks whether the map contains the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
true if the map contains the key

put

public java.lang.Object put(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3,
                            java.lang.Object value)
Stores the value against the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
value - the value to store
Returns:
the value previously mapped to this combined key, null if none

remove

public java.lang.Object remove(java.lang.Object key1,
                               java.lang.Object key2,
                               java.lang.Object key3)
Removes the specified multi-key from this map.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
the value mapped to the removed key, null if key not in map

hash

protected int hash(java.lang.Object key1,
                   java.lang.Object key2,
                   java.lang.Object key3)
Gets the hash code for the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
the hash code

isEqualKey

protected boolean isEqualKey(AbstractHashedMap.HashEntry entry,
                             java.lang.Object key1,
                             java.lang.Object key2,
                             java.lang.Object key3)
Is the key equal to the combined key.

Parameters:
entry - the entry to compare to
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
true if the key matches

get

public java.lang.Object get(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3,
                            java.lang.Object key4)
Gets the value mapped to the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
the mapped value, null if no match

containsKey

public boolean containsKey(java.lang.Object key1,
                           java.lang.Object key2,
                           java.lang.Object key3,
                           java.lang.Object key4)
Checks whether the map contains the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
true if the map contains the key

put

public java.lang.Object put(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3,
                            java.lang.Object key4,
                            java.lang.Object value)
Stores the value against the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
value - the value to store
Returns:
the value previously mapped to this combined key, null if none

remove

public java.lang.Object remove(java.lang.Object key1,
                               java.lang.Object key2,
                               java.lang.Object key3,
                               java.lang.Object key4)
Removes the specified multi-key from this map.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
the value mapped to the removed key, null if key not in map

hash

protected int hash(java.lang.Object key1,
                   java.lang.Object key2,
                   java.lang.Object key3,
                   java.lang.Object key4)
Gets the hash code for the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
the hash code

isEqualKey

protected boolean isEqualKey(AbstractHashedMap.HashEntry entry,
                             java.lang.Object key1,
                             java.lang.Object key2,
                             java.lang.Object key3,
                             java.lang.Object key4)
Is the key equal to the combined key.

Parameters:
entry - the entry to compare to
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
true if the key matches

get

public java.lang.Object get(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3,
                            java.lang.Object key4,
                            java.lang.Object key5)
Gets the value mapped to the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
Returns:
the mapped value, null if no match

containsKey

public boolean containsKey(java.lang.Object key1,
                           java.lang.Object key2,
                           java.lang.Object key3,
                           java.lang.Object key4,
                           java.lang.Object key5)
Checks whether the map contains the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
Returns:
true if the map contains the key

put

public java.lang.Object put(java.lang.Object key1,
                            java.lang.Object key2,
                            java.lang.Object key3,
                            java.lang.Object key4,
                            java.lang.Object key5,
                            java.lang.Object value)
Stores the value against the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
value - the value to store
Returns:
the value previously mapped to this combined key, null if none

remove

public java.lang.Object remove(java.lang.Object key1,
                               java.lang.Object key2,
                               java.lang.Object key3,
                               java.lang.Object key4,
                               java.lang.Object key5)
Removes the specified multi-key from this map.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
Returns:
the value mapped to the removed key, null if key not in map

hash

protected int hash(java.lang.Object key1,
                   java.lang.Object key2,
                   java.lang.Object key3,
                   java.lang.Object key4,
                   java.lang.Object key5)
Gets the hash code for the specified multi-key.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
Returns:
the hash code

isEqualKey

protected boolean isEqualKey(AbstractHashedMap.HashEntry entry,
                             java.lang.Object key1,
                             java.lang.Object key2,
                             java.lang.Object key3,
                             java.lang.Object key4,
                             java.lang.Object key5)
Is the key equal to the combined key.

Parameters:
entry - the entry to compare to
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
key5 - the fifth key
Returns:
true if the key matches

removeAll

public boolean removeAll(java.lang.Object key1)
Removes all mappings where the first key is that specified.

This method removes all the mappings where the MultiKey has one or more keys, and the first matches that specified.

Parameters:
key1 - the first key
Returns:
true if any elements were removed

removeAll

public boolean removeAll(java.lang.Object key1,
                         java.lang.Object key2)
Removes all mappings where the first two keys are those specified.

This method removes all the mappings where the MultiKey has two or more keys, and the first two match those specified.

Parameters:
key1 - the first key
key2 - the second key
Returns:
true if any elements were removed

removeAll

public boolean removeAll(java.lang.Object key1,
                         java.lang.Object key2,
                         java.lang.Object key3)
Removes all mappings where the first three keys are those specified.

This method removes all the mappings where the MultiKey has three or more keys, and the first three match those specified.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
Returns:
true if any elements were removed

removeAll

public boolean removeAll(java.lang.Object key1,
                         java.lang.Object key2,
                         java.lang.Object key3,
                         java.lang.Object key4)
Removes all mappings where the first four keys are those specified.

This method removes all the mappings where the MultiKey has four or more keys, and the first four match those specified.

Parameters:
key1 - the first key
key2 - the second key
key3 - the third key
key4 - the fourth key
Returns:
true if any elements were removed

checkKey

protected void checkKey(java.lang.Object key)
Check to ensure that input keys are valid MultiKey objects.

Parameters:
key - the key to check

clone

public java.lang.Object clone()
Clones the map without cloning the keys or values.

Overrides:
clone in class java.lang.Object
Returns:
a shallow clone

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)
Puts the key and value into the map, where the key must be a non-null MultiKey object.

Specified by:
put in interface java.util.Map
Parameters:
key - the non-null MultiKey object
value - the value to store
Returns:
the previous value for the key
Throws:
java.lang.NullPointerException - if the key is null
java.lang.ClassCastException - if the key is not a MultiKey

putAll

public void putAll(java.util.Map mapToCopy)
Copies all of the keys and values from the specified map to this map. Each key must be non-null and a MultiKey object.

Specified by:
putAll in interface java.util.Map
Parameters:
mapToCopy - to this map
Throws:
java.lang.NullPointerException - if the mapToCopy or any key within is null
java.lang.ClassCastException - if any key in mapToCopy is not a MultiKey

mapIterator

public MapIterator mapIterator()
Description copied from interface: IterableMap
Obtains a MapIterator over the map.

A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or cast to Map Entry objects. 

 IterableMap map = new HashedMap();
 MapIterator it = map.mapIterator();
 while (it.hasNext()) {
   Object key = it.next();
   Object value = it.getValue();
   it.setValue("newValue");
 }

Specified by:
mapIterator in interface IterableMap
Returns:
a map iterator

size

public int size()
Specified by:
size in interface java.util.Map

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface java.util.Map

containsKey

public boolean containsKey(java.lang.Object key)
Specified by:
containsKey in interface java.util.Map

containsValue

public boolean containsValue(java.lang.Object value)
Specified by:
containsValue in interface java.util.Map

get

public java.lang.Object get(java.lang.Object key)
Specified by:
get in interface java.util.Map

remove

public java.lang.Object remove(java.lang.Object key)
Specified by:
remove in interface java.util.Map

clear

public void clear()
Specified by:
clear in interface java.util.Map

keySet

public java.util.Set keySet()
Specified by:
keySet in interface java.util.Map

values

public java.util.Collection values()
Specified by:
values in interface java.util.Map

entrySet

public java.util.Set entrySet()
Specified by:
entrySet in interface java.util.Map

equals

public boolean equals(java.lang.Object obj)
Specified by:
equals in interface java.util.Map
Overrides:
equals in class java.lang.Object

hashCode

public int hashCode()
Specified by:
hashCode in interface java.util.Map
Overrides:
hashCode in class java.lang.Object

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object
Overview  Package   Class  Use  Tree  Deprecated  Index  Help 
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD
Copyright © 2001-2008 The Apache Software Foundation. All Rights Reserved.