org.exolab.core.database.recman
Class PMDHashMap

java.lang.Object
  org.exolab.core.foundation.PersistentObject
      org.exolab.core.database.recman.PMDHashMap

All Implemented Interfaces:

java.lang.Cloneable, java.io.Externalizable, HashMapIfc, PersistentCapableIfc, java.io.Serializable

public class PMDHashMap

extends PersistentObject

implements HashMapIfc, java.io.Externalizable

This is an implementation of the HashMapIfc specific to the page managed database where references to objects are managed as PMDHandle instances rather than the objects themselves. This is necessary to optimise the concurrency and performance of the database.

In addition this class deals with PersistentObjects rather than just Object instance, since it assumes you are using this clas in a persistence context. Therefore some method, that take an Object may throw a runtime exception if the objects are not of this type.

Finally, an instance of this class is created within the context of a session and within a valid transaction....which I don't have a plan for

Instrument for better serialization by overriding the writeObject and readObject methods in a later version

Version:

$Revision: 1.4 $ $Date: 2001/06/12 07:11:35 $

Author:

Jim Alateras

See Also:

Serialized Form

Constructor Summary

PMDHashMap()

Method Summary

void	clear() Clear the map
boolean	containsKey(java.lang.Object key) Return true if the specified key maps to an element in the map
boolean	containsValue(PersistentCapableIfc element) Test to see whether the map contains the specified value
java.util.Enumeration	elements() Return an enumeration of all the elements in the map
PersistentCapableIfc	get(java.lang.Object key) Return the object mapped to this key.
java.lang.Object	getMapObject() Return a refernece to the enclosed map.
boolean	isEmpty() Test for an empty hashmap
java.util.Enumeration	keys() Return the enumeration of all keys in the map
PersistentCapableIfc	put(java.lang.Object key, PersistentCapableIfc element) Add the key and associated element to the map and return a reference to the object.
void	readExternal(java.io.ObjectInput stream)
PersistentCapableIfc	remove(java.lang.Object key) Remove the object mapped to the specified key from the map and return it to the client
int	size() Return the size of the map
void	writeExternal(java.io.ObjectOutput stream)

Methods inherited from class org.exolab.core.foundation.PersistentObject

clone, equals, getId, getMinimumObjectSize, getObjectId, getObjectVersion, getVersion, setId, setMinimumObjectSize, setObjectId, setObjectVersion, setVersion

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.exolab.core.foundation.PersistentCapableIfc

getMinimumObjectSize, getObjectId, getObjectVersion, setMinimumObjectSize

Constructor Detail

PMDHashMap

public PMDHashMap()

Method Detail

size

public int size()

Return the size of the map

Specified by:

size in interface HashMapIfc

Returns:

int

isEmpty

public boolean isEmpty()

Test for an empty hashmap

Specified by:

isEmpty in interface HashMapIfc

Returns:

boolean true if empty; false otherwise

keys

public java.util.Enumeration keys()

Return the enumeration of all keys in the map

Specified by:

keys in interface HashMapIfc

Returns:

Enumeration

elements

public java.util.Enumeration elements()

Return an enumeration of all the elements in the map

Specified by:

elements in interface HashMapIfc

Returns:

Enumeration

containsValue

public boolean containsValue(PersistentCapableIfc element)

Test to see whether the map contains the specified value

Specified by:

containsValue in interface HashMapIfc

Parameters:

element - element to test against

Returns:

boolean true if key is mapped; false otherwise

containsKey

public boolean containsKey(java.lang.Object key)

Return true if the specified key maps to an element in the map

Specified by:

containsKey in interface HashMapIfc

Parameters:

key - key to test against

Returns:

boolean true if it maps; false otherwise

get

public PersistentCapableIfc get(java.lang.Object key)

Return the object mapped to this key.

Specified by:

get in interface HashMapIfc

Parameters:

key - key to lookup

Returns:

PersistentCapableIfc

put

public PersistentCapableIfc put(java.lang.Object key,
                                PersistentCapableIfc element)

Add the key and associated element to the map and return a reference to the object. In this implementation of the HashMapIfc the element must also be of type PersistentCapableIfc

Specified by:

put in interface HashMapIfc

Parameters:

key - key to map

element - corresponding element

Returns:

PersistentCapableIfc

remove

public PersistentCapableIfc remove(java.lang.Object key)

Remove the object mapped to the specified key from the map and return it to the client

Specified by:

remove in interface HashMapIfc

Parameters:

key - key to remove

clear

public void clear()

Clear the map

Specified by:

clear in interface HashMapIfc

getMapObject

public java.lang.Object getMapObject()

Return a refernece to the enclosed map. To be used it will have be cast to the Hashtable

Specified by:

getMapObject in interface HashMapIfc

Returns:

Object

writeExternal

public void writeExternal(java.io.ObjectOutput stream)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Overrides:

writeExternal in class PersistentObject

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput stream)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Overrides:

readExternal in class PersistentObject

Throws:

java.io.IOException

java.lang.ClassNotFoundException