org.jcoderz.commons.util
Class HashCodeUtil

java.lang.Object
  org.jcoderz.commons.util.HashCodeUtil

public final class HashCodeUtil
extends Object

Collected methods which allow easy implementation of hashCode. Example use case:

 public int hashCode ()
 {
    int result = HashCodeUtil.SEED;
    //collect the contributions of various fields
    result = HashCodeUtil.hash(result, mPrimitive);
    result = HashCodeUtil.hash(result, mObject);
    result = HashCodeUtil.hash(result, mArray);
    return result;
 }
 

Author:

Michael Griffel

Field Summary

static int

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

Method Summary

static int	hash(int aSeed, boolean aBoolean) Constructs a new seed using the given Boolean and the previous seed.
static int	hash(int aSeed, char aChar) Constructs a new seed using the given boolean and the previous seed.
static int	hash(int aSeed, double aDouble) Constructs a new seed using the given double and the previous seed.
static int	hash(int aSeed, float aFloat) Constructs a new seed using the given float and the previous seed.
static int	hash(int aSeed, int aInt) Constructs a new seed using the given integer and the previous seed.
static int	hash(int aSeed, long aLong) Constructs a new seed using the given long and the previous seed.
static int	hash(int aSeed, Object aObject) Constructs a new seed using the given object and the previous seed.

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

Method Detail

hash

public static int hash(int aSeed,
                       boolean aBoolean)

Constructs a new seed using the given Boolean and the previous seed.

Parameters:

aSeed - the previous seed value.

aBoolean - the Boolean that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       char aChar)

Constructs a new seed using the given boolean and the previous seed.

Parameters:

aSeed - the previous seed value.

aChar - the character that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       int aInt)

Constructs a new seed using the given integer and the previous seed. Note that byte and short are handled by this method, through implicit conversion.

Parameters:

aSeed - the previous seed value.

aInt - the integer that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       long aLong)

Constructs a new seed using the given long and the previous seed.

Parameters:

aSeed - the previous seed value.

aLong - the long value that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       float aFloat)

Constructs a new seed using the given float and the previous seed.

Parameters:

aSeed - the previous seed value.

aFloat - the float that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       double aDouble)

Constructs a new seed using the given double and the previous seed.

Parameters:

aSeed - the previous seed value.

aDouble - the double that should be added to the new seed.

Returns:

the new seed.

hash

public static int hash(int aSeed,
                       Object aObject)

Constructs a new seed using the given object and the previous seed. 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 - the previous seed value.

aObject - the integer that should be added to the new seed.

Returns:

the new seed.