jodd.util

Class HashCode

java.lang.Object

jodd.util.HashCode

public class HashCode
extends java.lang.Object

Collected methods which allow easy implementation of hashCode(). Based on items #7 and #8 from "Effective Java" book.

Usage scenario:

 int result = HashCodeUtil.SEED;
 result = HashCodeUtil.hash(result, value1);
 result = HashCodeUtil.hash(result, value2);
 ...
 return result;
 

Field Summary

Fields

Modifier and Type	Field and Description
static int	PRIME
static int	SEED An initial hash code value to which is added contributions from fields.

Constructor Summary

Constructors

Constructor and Description
HashCode()

Method Summary

Modifier and Type	Method and Description
static int	hash(int seed, boolean aBoolean) Calculates hash code for booleans.
static int	hash(int seed, boolean[] booleanArray) Calculates hash code for boolean array.
static int	hash(int seed, byte[] byteArray) Calculates hash code for byte array.
static int	hash(int seed, char aChar) Calculates hash code for chars.
static int	hash(int seed, char[] charArray) Calculates hash code for char array.
static int	hash(int seed, double aDouble) Calculates hash code for doubles.
static int	hash(int seed, double[] doubleArray) Calculates hash code for double array.
static int	hash(int seed, float aFloat) Calculates hash code for floats.
static int	hash(int seed, float[] floatArray) Calculates hash code for float array.
static int	hash(int seed, int anInt) Calculates hash code for ints.
static int	hash(int seed, int[] intArray) Calculates hash code for int array.
static int	hash(int seed, long aLong) Calculates hash code for longs.
static int	hash(int seed, long[] longArray) Calculates hash code for long array.
static int	hash(int seed, java.lang.Object aObject) Calculates hash code for Objects.
static int	hash(int seed, short[] shortArray) Calculates hash code for short array.
static int	hashBooleanArray(int seed, boolean... booleanArray) Calculates hash code for boolean array.
static int	hashByteArray(int seed, byte... byteArray) Calculates hash code for byte array.
static int	hashCharArray(int seed, char... charArray) Calculates hash code for char array.
static int	hashDoubleArray(int seed, double... doubleArray) Calculates hash code for double array.
static int	hashFloatArray(int seed, float... floatArray) Calculates hash code for float array.
static int	hashIntArray(int seed, int... intArray) Calculates hash code for int array.
static int	hashLongArray(int seed, long... longArray) Calculates hash code for long array.
static int	hashShortArray(int seed, short... shortArray) Calculates hash code for short array.
static int	smear(int hashCode) Smear hash code.

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 hash code value to which is added contributions from fields. Using a non-zero value decreases collisions of hash code values.

See Also:

Constant Field Values

PRIME

public static final int PRIME

See Also:

Constant Field Values

Constructor Detail

HashCode

public HashCode()

Method Detail

smear

public static int smear(int hashCode)

Smear hash code.

hash

public static int hash(int seed,
                       boolean aBoolean)

Calculates hash code for booleans.

hash

public static int hash(int seed,
                       boolean[] booleanArray)

Calculates hash code for boolean array.

hashBooleanArray

public static int hashBooleanArray(int seed,
                                   boolean... booleanArray)

Calculates hash code for boolean array.

hash

public static int hash(int seed,
                       char aChar)

Calculates hash code for chars.

hash

public static int hash(int seed,
                       char[] charArray)

Calculates hash code for char array.

hashCharArray

public static int hashCharArray(int seed,
                                char... charArray)

Calculates hash code for char array.

hash

public static int hash(int seed,
                       int anInt)

Calculates hash code for ints.

hash

public static int hash(int seed,
                       int[] intArray)

Calculates hash code for int array.

hashIntArray

public static int hashIntArray(int seed,
                               int... intArray)

Calculates hash code for int array.

hash

public static int hash(int seed,
                       short[] shortArray)

Calculates hash code for short array.

hashShortArray

public static int hashShortArray(int seed,
                                 short... shortArray)

Calculates hash code for short array.

hash

public static int hash(int seed,
                       byte[] byteArray)

Calculates hash code for byte array.

hashByteArray

public static int hashByteArray(int seed,
                                byte... byteArray)

Calculates hash code for byte array.

hash

public static int hash(int seed,
                       long aLong)

Calculates hash code for longs.

hash

public static int hash(int seed,
                       long[] longArray)

Calculates hash code for long array.

hashLongArray

public static int hashLongArray(int seed,
                                long... longArray)

Calculates hash code for long array.

hash

public static int hash(int seed,
                       float aFloat)

Calculates hash code for floats.

hash

public static int hash(int seed,
                       float[] floatArray)

Calculates hash code for float array.

hashFloatArray

public static int hashFloatArray(int seed,
                                 float... floatArray)

Calculates hash code for float array.

hash

public static int hash(int seed,
                       double aDouble)

Calculates hash code for doubles.

hash

public static int hash(int seed,
                       double[] doubleArray)

Calculates hash code for double array.

hashDoubleArray

public static int hashDoubleArray(int seed,
                                  double... doubleArray)

Calculates hash code for double array.

hash

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

Calculates hash code for Objects. Object 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.