Moved to builder subpackage
git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137015 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne
parent
370914eb5a
commit
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@ -1,409 +0,0 @@
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package org.apache.commons.lang;
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2002 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution, if
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* any, must include the following acknowlegement:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowlegement may appear in the software itself,
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* if and wherever such third-party acknowlegements normally appear.
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*
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* 4. The names "The Jakarta Project", "Commons", and "Apache Software
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* Foundation" must not be used to endorse or promote products derived
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* from this software without prior written permission. For written
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* permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache"
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* nor may "Apache" appear in their names without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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/**
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* <code>HashCode</code> generation routines.
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* <p>
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* This class enables a good hashcode to be built for any class. It follows
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* the rules laid out in the book Effective Java, by Joshua Bloch. Writing a
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* good hashCode is actually quite difficult. This class aims to simplify the
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* process.
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* <p>
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* All relevant fields from the object should be included in the hashCode. Derived
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* fields may be excluded. In general, any field used in the equals method must be
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* used in the hashCode method.
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* <p>
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* To use this class write code as follows:
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* <code>
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* public class Person {
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* String name;
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* int age;
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* boolean isSmoker;
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*
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* ...
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*
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* public int hashCode() {
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* // you pick a hard-coded, randomly chosen, non-zero, odd number
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* // ideally different for each class
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* return new HashCodeBuilder(17).
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* append(name).
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* append(age).
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* append(smoker).
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* toHashCode();
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* }
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* }
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* </code>
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*
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* @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
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* @version $Id: HashCodeBuilder.java,v 1.1 2002/08/15 22:37:29 scolebourne Exp $
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*/
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public class HashCodeBuilder {
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/**
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* Constant to use in building the hashCode
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*/
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private final int iConstant;
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/**
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* Running total of the hashCode
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*/
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private int iTotal = 0;
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/**
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* Constructor for HashCodeBuilder.
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* This constructor uses two hard coded choices for the constants needed
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* to build a hashCode.
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*/
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public HashCodeBuilder() {
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super();
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iConstant = 37;
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iTotal = 17;
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}
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/**
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* Constructor for HashCodeBuilder.
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* Two randomly chosen, non-zero, odd numbers must be passed in. Ideally
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* these should be different for each class, however this is not vital.
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* Prime numbers are preferred, especially for the multiplier.
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*
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* @param initialNonZeroOddNumber
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* @param multiplierNonZeroOddNumber
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* @throws IllegalArgumentException if the number is zero or even
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*/
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public HashCodeBuilder(int initialNonZeroOddNumber, int multiplierNonZeroOddNumber) {
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super();
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if (initialNonZeroOddNumber == 0) {
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throw new IllegalArgumentException("HashCodeBuilder requires a non zero initial value");
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}
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if (initialNonZeroOddNumber % 2 == 0) {
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throw new IllegalArgumentException("HashCodeBuilder requires an odd initial value");
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}
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if (multiplierNonZeroOddNumber == 0) {
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throw new IllegalArgumentException("HashCodeBuilder requires a non zero multiplier");
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}
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if (multiplierNonZeroOddNumber % 2 == 0) {
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throw new IllegalArgumentException("HashCodeBuilder requires an odd multiplier");
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}
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iConstant = multiplierNonZeroOddNumber;
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iTotal = initialNonZeroOddNumber;
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}
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/**
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* Append a hashCode for an Object.
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*
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* @param object the object to add to the hashCode
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* @return updated totalSoFar
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*/
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public HashCodeBuilder append(Object object) {
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if (object == null) {
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iTotal = iTotal * iConstant;
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} else {
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iTotal = iTotal * iConstant + object.hashCode();
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}
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return this;
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}
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/**
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* Append a hashCode for a long.
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*
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* @param value the long to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(long value) {
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iTotal = iTotal * iConstant + ((int) (value ^ (value >> 32)));
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return this;
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}
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/**
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* Append a hashCode for an int.
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*
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* @param value the int to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(int value) {
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iTotal = iTotal * iConstant + value;
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return this;
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}
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/**
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* Append a hashCode for a short.
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*
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* @param value the short to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(short value) {
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iTotal = iTotal * iConstant + (int) value;
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return this;
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}
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/**
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* Append a hashCode for a char.
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*
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* @param value the char to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(char value) {
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iTotal = iTotal * iConstant + (int) value;
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return this;
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}
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/**
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* Append a hashCode for a byte.
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*
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* @param value the byte to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(byte value) {
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iTotal = iTotal * iConstant + (int) value;
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return this;
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}
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/**
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* Append a hashCode for a double.
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*
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* @param value the double to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(double value) {
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return append(Double.doubleToLongBits(value));
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}
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/**
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* Append a hashCode for a float.
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*
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* @param value the float to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(float value) {
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iTotal = iTotal * iConstant + Float.floatToIntBits(value);
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return this;
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}
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/**
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* Append a hashCode for a long.
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*
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* @param value the long to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(boolean value) {
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iTotal = iTotal * iConstant + (value ? 0 : 1);
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return this;
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}
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/**
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* Append a hashCode for an Object array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(Object[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a long array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(long[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for an int array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(int[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a short array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(short[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a char array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(char[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a byte array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(byte[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a double array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(double[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a float array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(float[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Append a hashCode for a boolean array.
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*
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* @param array the array to add to the hashCode
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* @return this
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*/
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public HashCodeBuilder append(boolean[] array) {
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if (array == null) {
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iTotal = iTotal * iConstant;
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} else {
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for (int i = 0; i < array.length; i++) {
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append(array[i]);
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}
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}
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return this;
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}
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/**
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* Return the computed hashCode
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*
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* @return int hashCode based on the fields appended
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*/
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public int toHashCode() {
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return iTotal;
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}
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}
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