org.opensubsystems.core.util
Class HashCodeUtils

java.lang.Object
  org.opensubsystems.core.util.HashCodeUtils

public final class HashCodeUtils
extends java.lang.Object

Collection of methods making implementation of hashcode easier. Example how hashCode can be implemented using this method: public int hashCode() { int iResult = HashCodeUtils.SEED; iResult = HashCodeUtils.hash(iResult, primitiveValue); iResult = HashCodeUtils.hash(iResult, object); iResult = HashCodeUtils.hash(iResult, array); return iResult; } This code was inspired by class published at http://www.javapractices.com/Topic28.cjp

Version:

$Id: HashCodeUtils.java,v 1.3 2007/01/07 06:14:00 bastafidli Exp $

Author:

Miro Halas

Code reviewer:

Miro Halas

Code reviewed:

1.1 2005/07/29 07:36:24 bastafidli

Field Summary

static int	ODD_PRIME_NUMBER Constant to add to seed or previous term.
static int	SEED An initial value to decreases collisons of computed values.

Method Summary

protected static int	firstTerm(int iSeed) Compute first term for hashcode
static int	hash(int iSeed, boolean bValue) Hash for booleans.
static int	hash(int iSeed, char cValue) Hash for chars.
static int	hash(int iSeed, double dValue) Hash for doubles.
static int	hash(int iSeed, float fValue) Hash for floats.
static int	hash(int iSeed, int iValue) Hash for ints.
static int	hash(int iSeed, long lValue) Hash for longs.
static int	hash(int iSeed, java.lang.Object oValue) Hash for objects .
protected static boolean	isArray(java.lang.Object oObject) Test if object is an array

Methods inherited from class java.lang.Object

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

Field Detail

SEED

public static final int SEED

An initial value to decreases collisons of computed values.

See Also:

Constant Field Values

ODD_PRIME_NUMBER

public static final int ODD_PRIME_NUMBER

Constant to add to seed or previous term.

See Also:

Constant Field Values

Method Detail

hash

public static int hash(int iSeed,
                       boolean bValue)

Hash for booleans.

Parameters:

iSeed - - previous hashcode contributor or seed value

bValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       char cValue)

Hash for chars.

Parameters:

iSeed - - previous hashcode contributor or seed value

cValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       int iValue)

Hash for ints. Byte and short are handled by this method, through implicit conversion.

Parameters:

iSeed - - previous hashcode contributor or seed value

iValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       long lValue)

Hash for longs.

Parameters:

iSeed - - previous hashcode contributor or seed value

lValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       float fValue)

Hash for floats.

Parameters:

iSeed - - previous hashcode contributor or seed value

fValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       double dValue)

Hash for doubles.

Parameters:

iSeed - - previous hashcode contributor or seed value

dValue - - value contributing to hashcode

Returns:

int - computed hashcode contributor

hash

public static int hash(int iSeed,
                       java.lang.Object oValue)

Hash for objects .

Parameters:

iSeed - - previous hashcode contributor or seed value

oValue - - value contributing to hashcode. It is a possibly null object field, and possibly an array. If it is an array, then each element may be a primitive or a possibly null object.

Returns:

int - computed hashcode contributor

firstTerm

protected static int firstTerm(int iSeed)

Compute first term for hashcode

Parameters:

iSeed - - value to use to compute first temr

Returns:

int - hashcode contributor

isArray

protected static boolean isArray(java.lang.Object oObject)

Test if object is an array

Parameters:

oObject - - object to test

Returns:

boolean