| HashCode.java |
/***************************************
* *
* JBoss: The OpenSource J2EE WebOS *
* *
* Distributable under LGPL license. *
* See terms of license at gnu.org. *
* *
***************************************/
package org.jboss.util;
import java.io.Serializable;
/**
* A hash-code generator and a collection of static hash-code generation
* methods.
*
* @version <tt>$Revision: 1.1.28.1 $</tt>
* @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
*/
public final class HashCode
implements Serializable, Cloneable, Comparable
{
static final long serialVersionUID = 2391396931740264021L;
/** Hashcode for a 'null' value. */
private static final int NULL_HASHCODE = 0;
/** Hashcode for a 'true' boolean */
private static final int TRUE_HASHCODE = 1231; // completely arbitrary
/** Hashcode for a 'false' boolean */
private static final int FALSE_HASHCODE = 1237; // completely arbitrary
/** The hash-code value. */
private int value;
/**
* Construct a new <tt>HashCode</tt> using the given <tt>int</tt> as the
* base value.
*
* @param value <tt>int</tt> to use as the base value.
*/
public HashCode(final int value) {
this.value = value;
}
/**
* Construct a new <tt>HashCode</tt>.
*/
public HashCode() {
this(0);
}
/**
* Add the hash-code of the given value.
*
* @param b Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final boolean b) {
value ^= generate(b);
return this;
}
/**
* Add the hash-code of the given value.
*
* @param n Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final byte n) {
value ^= n;
return this;
}
/**
* Add the hash-code of the given value.
*
* @param n Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final char n) {
value ^= n;
return this;
}
/**
* Add the hash-code of the given value.
*
* @param n Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final short n) {
value ^= n;
return this;
}
/**
* Add the hash-code of the given value.
*
* @param n Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final int n) {
value ^= n;
return this;
}
/**
* Add the hash-code of the given value.
*
* @param n Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final long n) {
value ^= generate(n);
return this;
}
/**
* Add the hash-code of the given value.
*
* @param f Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final float f) {
value ^= generate(f);
return this;
}
/**
* Add the hash-code of the given value.
*
* @param f Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final double f) {
value ^= generate(f);
return this;
}
/**
* Add the hash-code of the given object.
*
* @param obj Value to get hash-code from.
* @return <i>This</i> <tt>HashCode</tt>.
*/
public HashCode add(final Object obj) {
value ^= generate(obj);
return this;
}
/**
* Get the hash-code.
*
* @return Hash-code.
*/
public int hashCode() {
return (int)value;
}
/**
* Compares this object with the specified <tt>int</tt> for order.
*
* @param other Value to compare with.
* @return A negative integer, zero, or a positive integer as
* this object is less than, equal to, or greater than
* the specified object.
*/
public int compareTo(final int other) {
return (value < other) ? -1 : (value == other) ? 0 : 1;
}
/**
* Compares this object with the specified object for order.
*
* @param other Value to compare with.
* @return A negative integer, zero, or a positive integer as
* this object is less than, equal to, or greater than
* the specified object.
*
* @throws ClassCastException Object is not a <tt>HashCode</tt>.
*/
public int compareTo(final Object obj) throws ClassCastException {
HashCode hashCode = (HashCode)obj;
return compareTo(hashCode.value);
}
/**
* Test the equality of this <tt>HashCode</tt> and another object.
*
* @param obj Object to test equality with.
* @return True if object is equal.
*/
public boolean equals(final Object obj) {
if (obj == this) return true;
if (obj != null && obj.getClass() == getClass()) {
return value == ((HashCode)obj).value;
}
return false;
}
/**
* Return a string representation of this <tt>HashCode</tt>.
*
* @return A string representation of this <tt>HashCode</tt>.
*/
public String toString() {
return String.valueOf(value);
}
/**
* Return a cloned copy of this <tt>HashCode</tt>.
*
* @return Cloned <tt>HashCode</tt>.
*/
public Object clone() {
try {
return super.clone();
}
catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/////////////////////////////////////////////////////////////////////////
// Generation Methods //
/////////////////////////////////////////////////////////////////////////
/**
* Generate a hash code for a boolean value.
*
* @param value Boolean value to generate hash code from.
* @return Hash code.
*/
public static int generate(final boolean value) {
return value ? TRUE_HASHCODE : FALSE_HASHCODE;
}
/**
* Generate a hash code for a long value.
*
* @param value Long value to generate hash code from.
* @return Hash code.
*/
public static int generate(final long value) {
return (int)(value ^ (value >> 32));
}
/**
* Generate a hash code for a double value.
*
* @param value Double value to generate hash code from.
* @return Hash code.
*/
public static int generate(final double value) {
return generate(Double.doubleToLongBits(value));
}
/**
* Generate a hash code for a float value.
*
* @param value Float value to generate hash code from.
* @return Hash code.
*/
public static int generate(final float value) {
return Float.floatToIntBits(value);
}
/**
* Generate a hash code for a byte array.
*
* @param bytes An array of bytes to generate a hash code from.
* @return Hash code.
*/
public static int generate(final byte[] bytes) {
int hashcode = 0;
for (int i=0; i<bytes.length; i++) {
hashcode <<= 1;
hashcode ^= bytes[i];
}
return hashcode;
}
/**
* Generate a hash code for an object array.
*
* <p>Does not handle nested primitive array elements.
*
* @param array Array to generate hashcode for.
* @param deep True to traverse elements which are arrays to
* determine the elements hash code.
* @return Hash code.
*/
public static int generate(final Object array[], final boolean deep) {
int hashcode = 0;
for (int i=0; i<array.length; i++) {
if (deep && (array[i] instanceof Object[])) {
hashcode ^= generate((Object[])array[i], true);
}
else {
hashcode ^= array[i].hashCode();
}
}
return hashcode;
}
/**
* Generate a shallow hash code for an object array.
*
* @param array Array to generate hashcode for.
* @return Hash code.
*/
public static int generate(final Object array[]) {
return generate(array, false);
}
/**
* Generate a hash code for an object.
*
* @param obj Object to generate hashcode for.
* @return Hash code.
*/
public static int generate(final Object obj) {
if (obj != null) {
return obj.hashCode();
}
return NULL_HASHCODE;
}
}
| HashCode.java |