com.sosnoski.util.hashmap
Class ObjectObjectHashMap

java.lang.Object
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  +--com.sosnoski.util.ObjectHashBase
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        +--com.sosnoski.util.hashmap.ObjectKeyBase
              |
              +--com.sosnoski.util.hashmap.ObjectObjectHashMap

public class ObjectObjectHashMap

extends ObjectKeyBase

Hash map using Object values as keys mapped to Object values. This implementation is unsynchronized in order to provide the best possible performance for typical usage scenarios, so explicit synchronization must be implemented by a wrapper class or directly by the application in cases where instances are modified in a multithreaded environment. See the base classes for other details of the implementation.

Version:

1.1

Author:

Dennis M. Sosnoski

Field Summary

protected java.lang.Object[]	m_keyTable Array of key table slots.
protected java.lang.Object[]	m_valueTable Array of value table slots.

Fields inherited from class com.sosnoski.util.ObjectHashBase

DEFAULT_FILL, IDENTITY_COMP, IDENTITY_HASH, m_arraySize, m_entryCount, m_entryLimit, m_fillFraction, m_hitOffset, m_identCompare, m_identHash, MINIMUM_SIZE, STANDARD_HASH

Constructor Summary

ObjectObjectHashMap()
Default constructor.

ObjectObjectHashMap(int count)
Constructor with only size supplied.

ObjectObjectHashMap(int count, double fill)
Constructor with size and fill fraction specified.

ObjectObjectHashMap(int count, double fill, java.lang.Object tech)
Constructor with full specification.

ObjectObjectHashMap(int count, java.lang.Object tech)
Constructor with only size and hash technique supplied.

ObjectObjectHashMap(java.lang.Object tech)
Constructor with technique specified.

ObjectObjectHashMap(ObjectObjectHashMap base)
Copy (clone) constructor.

Method Summary

java.lang.Object	add(java.lang.Object key, java.lang.Object value) Add an entry to the table.
protected int	assignSlot(java.lang.Object key, java.lang.Object value) Assign slot for entry.
java.lang.Object	clone() Construct a copy of the table.
boolean	containsKey(java.lang.Object key) Check if an entry is present in the table.
java.lang.Object	get(java.lang.Object key) Find an entry in the table.
protected java.lang.Object[]	getKeyArray() Get the backing array of keys.
protected java.lang.Object	getValueArray() Get the backing array of values.
protected boolean	reinsert(int slot) Reinsert an entry into the hash map.
java.lang.Object	remove(java.lang.Object key) Remove an entry from the table.
protected void	restructure(java.lang.Object karray, java.lang.Object varray) Restructure the table.
protected void	setKeyArray(java.lang.Object array) Set the backing array of keys.
protected void	setValueArray(java.lang.Object array) Set the backing array of values.
java.util.Iterator	valueIterator() Return an iterator for the value Objects in this map.

Methods inherited from class com.sosnoski.util.hashmap.ObjectKeyBase

clear, internalRemove, iterator, reallocate

Methods inherited from class com.sosnoski.util.ObjectHashBase

ensureCapacity, freeSlot, growCapacity, size, standardFind, standardSlot, stepSlot

Methods inherited from class java.lang.Object

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

Field Detail

m_keyTable

protected java.lang.Object[] m_keyTable

Array of key table slots.

m_valueTable

protected java.lang.Object[] m_valueTable

Array of value table slots.

Constructor Detail

ObjectObjectHashMap

public ObjectObjectHashMap(int count,
                           double fill,
                           java.lang.Object tech)

Constructor with full specification.

Parameters:

count - number of values to assume in initial sizing of table

fill - fraction full allowed for table before growing

tech - hash technique specifier (one of STANDARD_HASH, IDENTITY_COMP, or IDENTITY_HASH, inherited from ObjectHashBase)

ObjectObjectHashMap

public ObjectObjectHashMap(int count,
                           double fill)

Constructor with size and fill fraction specified. Uses default hash technique.

Parameters:

count - number of values to assume in initial sizing of table

fill - fraction full allowed for table before growing

ObjectObjectHashMap

public ObjectObjectHashMap(int count,
                           java.lang.Object tech)

Constructor with only size and hash technique supplied. Uses default value for fill fraction.

Parameters:

count - number of values to assume in initial sizing of table

tech - hash technique specifier (one of STANDARD_HASH, IDENTITY_COMP, or IDENTITY_HASH, inherited from ObjectHashBase)

ObjectObjectHashMap

public ObjectObjectHashMap(int count)

Constructor with only size supplied. Uses default hash technique and value for fill fraction.

Parameters:

count - number of values to assume in initial sizing of table

ObjectObjectHashMap

public ObjectObjectHashMap(java.lang.Object tech)

Constructor with technique specified. Uses standard default values for size and fill fraction.

Parameters:

tech - hash technique specifier (one of STANDARD_HASH, IDENTITY_COMP, or IDENTITY_HASH, inherited from ObjectHashBase)

ObjectObjectHashMap

public ObjectObjectHashMap()

Default constructor.

ObjectObjectHashMap

public ObjectObjectHashMap(ObjectObjectHashMap base)

Copy (clone) constructor.

Parameters:

base - instance being copied

Method Detail

getKeyArray

protected final java.lang.Object[] getKeyArray()

Get the backing array of keys. This implementation of an abstract method is used by the type-agnostic base class code to access the array used for type-specific storage by the child class.

Overrides:

getKeyArray in class ObjectHashBase

Returns:

backing key array object

setKeyArray

protected final void setKeyArray(java.lang.Object array)

Set the backing array of keys. This implementation of an abstract method is used by the type-agnostic base class code to set the array used for type-specific storage by the child class.

Overrides:

setKeyArray in class ObjectHashBase

Parameters:

array - backing key array object

getValueArray

protected final java.lang.Object getValueArray()

Get the backing array of values. This implementation of an abstract method is used by the type-agnostic base class code to access the array used for type-specific storage by the child class.

Overrides:

getValueArray in class ObjectKeyBase

Returns:

backing key array object

setValueArray

protected final void setValueArray(java.lang.Object array)

Set the backing array of values. This implementation of an abstract method is used by the type-agnostic base class code to set the array used for type-specific storage by the child class.

Overrides:

setValueArray in class ObjectKeyBase

Parameters:

array - backing value array object

reinsert

protected final boolean reinsert(int slot)

Reinsert an entry into the hash map. This implementation of an abstract method is used when the table is being directly modified by the base class, and does not adjust the count present or check the table capacity.

Overrides:

reinsert in class ObjectKeyBase

Parameters:

slot - position of entry to be reinserted into hash map

Returns:

true if the slot number used by the entry has has changed, false if not

restructure

protected void restructure(java.lang.Object karray,
                           java.lang.Object varray)

Restructure the table. This implementation of an abstract method is used when the table is increasing or decreasing in size, and works directly with the old table representation arrays. It inserts pairs from the old arrays directly into the table without adjusting the count present or checking the table size.

Overrides:

restructure in class ObjectKeyBase

Parameters:

karray - array of keys

varray - array of values

assignSlot

protected int assignSlot(java.lang.Object key,
                         java.lang.Object value)

Assign slot for entry. Starts at the slot found by the hashed key value. If this slot is already occupied, it steps the slot number and checks the resulting slot, repeating until an unused slot is found. This method does not check for duplicate keys, so it should only be used for internal reordering of the tables.

Parameters:

key - to be added to table

value - associated value for key

Returns:

slot at which entry was added

add

public java.lang.Object add(java.lang.Object key,
                            java.lang.Object value)

Add an entry to the table. If the key is already present in the table, this replaces the existing value associated with the key.

Parameters:

key - key to be added to table (non-null)

value - associated value for key (non-null)

Returns:

value previously associated with key, or null if key not previously present in table

containsKey

public final boolean containsKey(java.lang.Object key)

Check if an entry is present in the table. This method is supplied to support the use of values matching the reserved not found value.

Parameters:

key - key for entry to be found

Returns:

true if key found in table, false if not

get

public final java.lang.Object get(java.lang.Object key)

Find an entry in the table.

Parameters:

key - key for entry to be returned

Returns:

value for key, or null if key not found

remove

public java.lang.Object remove(java.lang.Object key)

Remove an entry from the table. If multiple entries are present with the same key value, only the first one found will be removed.

Parameters:

key - key to be removed from table

Returns:

value associated with removed key, or null if key not found in table

valueIterator

public final java.util.Iterator valueIterator()

Return an iterator for the value Objects in this map. The iterator returns all values in arbitrary order, but is not "live". Any changes to the map while the iteration is in progress will give indeterminant results.

Returns:

iterator for values in array

clone

public java.lang.Object clone()

Construct a copy of the table.

Overrides:

clone in class java.lang.Object

Returns:

shallow copy of table