com.tangosol.util
Class ChainedMap

java.lang.Object
  java.util.AbstractMap
      com.tangosol.util.ChainedMap

All Implemented Interfaces:

Serializable, Map

public class ChainedMap
extends AbstractMap
implements Serializable

Chains two maps into one virtual map.

The contents of the first map take precedence over the contents in the second map. If there are already entries in the two maps when this map is constructed, then the keys in the second map that are also in the first map will be removed from the second map.

Since:

Coherence 2.4

Author:

cp 2004.03.24

Nested Class Summary

class

ChainedMap.EntrySet A set of entries backed by this map.

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry

Field Summary

protected Map	m_mapFirst The first map.
protected Map	m_mapSecond The second map.
protected ChainedMap.EntrySet	m_setEntries The entry set.

Constructor Summary

ChainedMap(Map mapFirst, Map mapSecond)
Construct a ChainedMap out of two maps.

Method Summary

boolean	containsKey(Object oKey) Returns true if this map contains a mapping for the specified key.
Set	entrySet() Returns a set view of the mappings contained in this map.
Object	get(Object oKey) Returns the value to which this map maps the specified key.
Map	getFirstMap() Get the first (front) map.
Map	getSecondMap() Get the second (back) map.
protected ChainedMap.EntrySet	instantiateEntrySet() (Factory pattern) Instantiate an Entry Set or subclass thereof.
Object	put(Object oKey, Object oValue) Associates the specified value with the specified key in this map.
Object	remove(Object oKey) Removes the mapping for this key from this map if present.
int	size() Returns the number of key-value mappings in this map.

Methods inherited from class java.util.AbstractMap

clear, clone, containsValue, equals, hashCode, isEmpty, keySet, putAll, toString, values

Field Detail

m_mapFirst

protected Map m_mapFirst

The first map.

m_mapSecond

protected Map m_mapSecond

The second map.

m_setEntries

protected transient ChainedMap.EntrySet m_setEntries

The entry set.

Constructor Detail

ChainedMap

public ChainedMap(Map mapFirst,
                  Map mapSecond)

Construct a ChainedMap out of two maps.

Parameters:

mapFirst - the map whose mappings are to be placed in this map.

Method Detail

getFirstMap

public Map getFirstMap()

Get the first (front) map.

Note: direct modifications of the returned map may cause an unpredictable behavior of the ChainedMap.

Returns:

the first Map

getSecondMap

public Map getSecondMap()

Get the second (back) map.

Note: direct modifications of the returned map may cause an unpredictable behavior of the ChainedMap.

Returns:

the second Map

size

public int size()

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Specified by:

size in interface Map

Overrides:

size in class AbstractMap

Returns:

the number of key-value mappings in this map

containsKey

public boolean containsKey(Object oKey)

Returns true if this map contains a mapping for the specified key.

Specified by:

containsKey in interface Map

Overrides:

containsKey in class AbstractMap

Parameters:

oKey - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

get

public Object get(Object oKey)

Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

Specified by:

get in interface Map

Overrides:

get in class AbstractMap

Parameters:

oKey - key whose associated value is to be returned

Returns:

the value to which this map maps the specified key, or null if the map contains no mapping for this key

put

public Object put(Object oKey,
                  Object oValue)

Associates the specified value with the specified key in this map. If the map previously contained a mapping for this key, the old value is replaced.

Specified by:

put in interface Map

Overrides:

put in class AbstractMap

Parameters:

oKey - key with which the specified value is to be associated

oValue - value to be associated with the specified key

Returns:

previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values

remove

public Object remove(Object oKey)

Removes the mapping for this key from this map if present.

Specified by:

remove in interface Map

Overrides:

remove in class AbstractMap

Parameters:

oKey - key whose mapping is to be removed from the map

Returns:

previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values

entrySet

public Set entrySet()

Returns a set view of the mappings contained in this map. Each element in the returned set is a Map.Entry. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Specified by:

entrySet in interface Map

Specified by:

entrySet in class AbstractMap

Returns:

a set view of the mappings contained in this map.

instantiateEntrySet

protected ChainedMap.EntrySet instantiateEntrySet()

(Factory pattern) Instantiate an Entry Set or subclass thereof. This method permits inheriting classes to easily override the implementation of the EntrySet object.

Returns:

an instance of EntrySet