com.bbn.openmap.util
Class HashCodeUtil

java.lang.Object
  com.bbn.openmap.util.HashCodeUtil

public final class HashCodeUtil
extends java.lang.Object

Collected methods which allow easy implementation of hashCode. Algorithm from Effective Java by Joshua Bloch. Implementation found at http://www.javapractices.com. Example use case:

 public int hashCode() {
     int result = HashCodeUtil.SEED;
     // collect the contributions of various fields
     result = HashCodeUtil.hash(result, fPrimitive);
     result = HashCodeUtil.hash(result, fObject);
     result = HashCodeUtil.hash(result, fArray);
     return result;
 }
 

Field Summary

static int

SEED An initial value for a hashCode, to which is added contributions from fields.

Constructor Summary

HashCodeUtil()

Method Summary

static int	hash(int aSeed, boolean aBoolean) hash booleans.
static int	hash(int aSeed, char aChar) hash chars.
static int	hash(int aSeed, double aDouble) hash for doubles
static int	hash(int aSeed, float aFloat) hash floats.
static int	hash(int aSeed, int aInt) hash ints.
static int	hash(int aSeed, long aLong) hash longs.
static int	hash(int aSeed, java.lang.Object aObject) aObject is a possibly-null object field, and possibly 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 for a hashCode, to which is added contributions from fields. Using a non-zero value decreases collisons of hashCode values.

See Also:

Constant Field Values

Constructor Detail

HashCodeUtil

public HashCodeUtil()

Method Detail

hash

public static int hash(int aSeed,
                       boolean aBoolean)

hash booleans.

Parameters:

aSeed - seeding int to start with

aBoolean - object to hash

Returns:

hash for boolean

hash

public static int hash(int aSeed,
                       char aChar)

hash chars.

Parameters:

aSeed - seeding int to start with

aChar - object to hash

Returns:

hash for char

hash

public static int hash(int aSeed,
                       int aInt)

hash ints.

Parameters:

aSeed - seeding int to start with

aInt - object to hash

Returns:

hash for int

hash

public static int hash(int aSeed,
                       long aLong)

hash longs.

Parameters:

aSeed - seeding int to start with

aLong - object to hash

Returns:

hash for long

hash

public static int hash(int aSeed,
                       float aFloat)

hash floats.

Parameters:

aSeed - seeding int to start with

aFloat - object to hash

Returns:

hash for float

hash

public static int hash(int aSeed,
                       double aDouble)

hash for doubles

Parameters:

aSeed - seeding int to start with

aDouble - to hash

Returns:

hash for double

hash

public static int hash(int aSeed,
                       java.lang.Object aObject)

aObject is a possibly-null object field, and possibly an array. If aObject is an array, then each element may be a primitive or a possibly-null object.

Parameters:

aSeed - seeding int to start with

aObject - object to hash

Returns:

hash for aObject