- /* ====================================================================
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 2002-2003 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution, if
- * any, must include the following acknowledgement:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowledgement may appear in the software itself,
- * if and wherever such third-party acknowledgements normally appear.
- *
- * 4. The names "The Jakarta Project", "Commons", and "Apache Software
- * Foundation" must not be used to endorse or promote products derived
- * from this software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache"
- * nor may "Apache" appear in their names without prior written
- * permission of the Apache Software Foundation.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- */
- package org.apache.commons.lang.builder;
-
- import java.lang.reflect.AccessibleObject;
- import java.lang.reflect.Field;
- import java.lang.reflect.Modifier;
-
- /**
- * <p>Assists in implementing {@link Object#hashCode()} methods.</p>
- *
- * <p> This class enables a good <code>hashCode</code> method to be built for any class. It
- * follows the rules laid out in the book
- * <a href="http://java.sun.com/docs/books/effective/index.html">Effective Java</a>
- * by Joshua Bloch. Writing a good <code>hashCode</code> method is actually quite
- * difficult. This class aims to simplify the process.</p>
- *
- * <p>All relevant fields from the object should be included in the
- * <code>hashCode</code> method. Derived fields may be excluded. In general, any
- * field used in the <code>equals</code> method must be used in the <code>hashCode</code>
- * method.</p>
- *
- * <p>To use this class write code as follows:</p>
- * <pre>
- * public class Person {
- * String name;
- * int age;
- * boolean isSmoker;
- * ...
- *
- * public int hashCode() {
- * // you pick a hard-coded, randomly chosen, non-zero, odd number
- * // ideally different for each class
- * return new HashCodeBuilder(17, 37).
- * append(name).
- * append(age).
- * append(smoker).
- * toHashCode();
- * }
- * }
- * </pre>
- *
- * <p>If required, the superclass <code>hashCode()</code> can be added
- * using {@link #appendSuper}.</p>
- *
- * <p>Alternatively, there is a method that uses reflection to determine
- * the fields to test. Because these fields are usually private, the method,
- * <code>reflectionHashCode</code>, uses <code>AccessibleObject.setAccessible</code> to
- * change the visibility of the fields. This will fail under a security manager,
- * unless the appropriate permissions are set up correctly. It is also slower
- * than testing explicitly.</p>
- *
- * <p>A typical invocation for this method would look like:</p>
- * <pre>
- * public int hashCode() {
- * return HashCodeBuilder.reflectionHashCode(this);
- * }
- * </pre>
- *
- * @author Stephen Colebourne
- * @author Gary Gregory
- * @author Pete Gieser
- * @since 1.0
- * @version $Id: HashCodeBuilder.java,v 1.20 2003/08/23 00:21:49 ggregory Exp $
- */
- public class HashCodeBuilder {
-
- /**
- * Constant to use in building the hashCode.
- */
- private final int iConstant;
- /**
- * Running total of the hashCode.
- */
- private int iTotal = 0;
-
- /**
- * <p>Constructor.</p>
- *
- * <p>This constructor uses two hard coded choices for the constants
- * needed to build a <code>hashCode</code>.</p>
- */
- public HashCodeBuilder() {
- super();
- iConstant = 37;
- iTotal = 17;
- }
-
- /**
- * <p>Constructor.</p>
- *
- * <p>Two randomly chosen, non-zero, odd numbers must be passed in.
- * Ideally these should be different for each class, however this is
- * not vital.</p>
- *
- * <p>Prime numbers are preferred, especially for the multiplier.</p>
- *
- * @param initialNonZeroOddNumber a non-zero, odd number used as the initial value
- * @param multiplierNonZeroOddNumber a non-zero, odd number used as the multiplier
- * @throws IllegalArgumentException if the number is zero or even
- */
- public HashCodeBuilder(int initialNonZeroOddNumber, int multiplierNonZeroOddNumber) {
- super();
- if (initialNonZeroOddNumber == 0) {
- throw new IllegalArgumentException("HashCodeBuilder requires a non zero initial value");
- }
- if (initialNonZeroOddNumber % 2 == 0) {
- throw new IllegalArgumentException("HashCodeBuilder requires an odd initial value");
- }
- if (multiplierNonZeroOddNumber == 0) {
- throw new IllegalArgumentException("HashCodeBuilder requires a non zero multiplier");
- }
- if (multiplierNonZeroOddNumber % 2 == 0) {
- throw new IllegalArgumentException("HashCodeBuilder requires an odd multiplier");
- }
- iConstant = multiplierNonZeroOddNumber;
- iTotal = initialNonZeroOddNumber;
- }
-
- //-------------------------------------------------------------------------
-
- /**
- * <p>This method uses reflection to build a valid hash code.</p>
- *
- * <p>This constructor uses two hard coded choices for the constants
- * needed to build a hash code.</p>
- *
- * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
- * fields. This means that it will throw a security exception if run under
- * a security manager, if the permissions are not set up correctly. It is
- * also not as efficient as testing explicitly.</p>
- *
- * <p>Transient members will be not be used, as they are likely derived
- * fields, and not part of the value of the <code>Object</code>.</p>
- *
- * <p>Static fields will not be tested. Superclass fields will be included.</p>
- *
- * @param object the Object to create a <code>hashCode</code> for
- * @return int hash code
- * @throws IllegalArgumentException if the object is <code>null</code>
- */
- public static int reflectionHashCode(Object object) {
- return reflectionHashCode(17, 37, object, false, null);
- }
-
- /**
- * <p>This method uses reflection to build a valid hash code.</p>
- *
- * <p>This constructor uses two hard coded choices for the constants needed
- * to build a hash code.</p>
- *
- * <p> It uses <code>AccessibleObject.setAccessible</code> to gain access to private
- * fields. This means that it will throw a security exception if run under
- * a security manager, if the permissions are not set up correctly. It is
- * also not as efficient as testing explicitly.</p>
- *
- * <P>If the TestTransients parameter is set to <code>true</code>, transient
- * members will be tested, otherwise they are ignored, as they are likely
- * derived fields, and not part of the value of the <code>Object</code>.</p>
- *
- * <p>Static fields will not be tested. Superclass fields will be included.</p>
- *
- * @param object the Object to create a <code>hashCode</code> for
- * @param testTransients whether to include transient fields
- * @return int hash code
- * @throws IllegalArgumentException if the object is <code>null</code>
- */
- public static int reflectionHashCode(Object object, boolean testTransients) {
- return reflectionHashCode(17, 37, object, testTransients, null);
- }
-
- /**
- * <p>This method uses reflection to build a valid hash code.</p>
- *
- * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
- * fields. This means that it will throw a security exception if run under
- * a security manager, if the permissions are not set up correctly. It is
- * also not as efficient as testing explicitly.</p>
- *
- * <p>Transient members will be not be used, as they are likely derived
- * fields, and not part of the value of the <code>Object</code>.</p>
- *
- * <p>Static fields will not be tested. Superclass fields will be included.</p>
- *
- * <p>Two randomly chosen, non-zero, odd numbers must be passed in. Ideally
- * these should be different for each class, however this is not vital.
- * Prime numbers are preferred, especially for the multiplier.</p>
- *
- * @param initialNonZeroOddNumber a non-zero, odd number used as the initial value
- * @param multiplierNonZeroOddNumber a non-zero, odd number used as the multiplier
- * @param object the Object to create a <code>hashCode</code> for
- * @return int hash code
- * @throws IllegalArgumentException if the Object is <code>null</code>
- * @throws IllegalArgumentException if the number is zero or even
- */
- public static int reflectionHashCode(
- int initialNonZeroOddNumber, int multiplierNonZeroOddNumber, Object object) {
- return reflectionHashCode(initialNonZeroOddNumber, multiplierNonZeroOddNumber, object, false, null);
- }
-
- /**
- * <p>This method uses reflection to build a valid hash code.</p>
- *
- * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
- * fields. This means that it will throw a security exception if run under
- * a security manager, if the permissions are not set up correctly. It is also
- * not as efficient as testing explicitly.</p>
- *
- * <p>If the TestTransients parameter is set to <code>true</code>, transient
- * members will be tested, otherwise they are ignored, as they are likely
- * derived fields, and not part of the value of the <code>Object</code>.</p>
- *
- * <p>Static fields will not be tested. Superclass fields will be included.</p>
- *
- * <p>Two randomly chosen, non-zero, odd numbers must be passed in. Ideally
- * these should be different for each class, however this is not vital.
- * Prime numbers are preferred, especially for the multiplier.</p>
- *
- * @param initialNonZeroOddNumber a non-zero, odd number used as the initial value
- * @param multiplierNonZeroOddNumber a non-zero, odd number used as the multiplier
- * @param object the Object to create a <code>hashCode</code> for
- * @param testTransients whether to include transient fields
- * @return int hash code
- * @throws IllegalArgumentException if the Object is <code>null</code>
- * @throws IllegalArgumentException if the number is zero or even
- */
- public static int reflectionHashCode(
- int initialNonZeroOddNumber, int multiplierNonZeroOddNumber,
- Object object, boolean testTransients) {
- return reflectionHashCode(initialNonZeroOddNumber, multiplierNonZeroOddNumber, object, testTransients, null);
- }
-
- /**
- * <p>This method uses reflection to build a valid hash code.</p>
- *
- * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
- * fields. This means that it will throw a security exception if run under
- * a security manager, if the permissions are not set up correctly. It is also
- * not as efficient as testing explicitly.</p>
- *
- * <p>If the TestTransients parameter is set to <code>true</code>, transient
- * members will be tested, otherwise they are ignored, as they are likely
- * derived fields, and not part of the value of the <code>Object</code>.</p>
- *
- * <p>Static fields will not be included. Superclass fields will be included
- * up to and including the specified superclass. A null superclass is treated
- * as java.lang.Object.</p>
- *
- * <p>Two randomly chosen, non-zero, odd numbers must be passed in. Ideally
- * these should be different for each class, however this is not vital.
- * Prime numbers are preferred, especially for the multiplier.</p>
- *
- * @param initialNonZeroOddNumber a non-zero, odd number used as the initial value
- * @param multiplierNonZeroOddNumber a non-zero, odd number used as the multiplier
- * @param object the Object to create a <code>hashCode</code> for
- * @param testTransients whether to include transient fields
- * @param reflectUpToClass the superclass to reflect up to (inclusive),
- * may be <code>null</code>
- * @return int hash code
- * @throws IllegalArgumentException if the Object is <code>null</code>
- * @throws IllegalArgumentException if the number is zero or even
- * @since 2.0
- */
- public static int reflectionHashCode(
- int initialNonZeroOddNumber,
- int multiplierNonZeroOddNumber,
- Object object,
- boolean testTransients,
- Class reflectUpToClass) {
-
- if (object == null) {
- throw new IllegalArgumentException("The object to build a hash code for must not be null");
- }
- HashCodeBuilder builder = new HashCodeBuilder(initialNonZeroOddNumber, multiplierNonZeroOddNumber);
- Class clazz = object.getClass();
- reflectionAppend(object, clazz, builder, testTransients);
- while (clazz.getSuperclass() != null && clazz != reflectUpToClass) {
- clazz = clazz.getSuperclass();
- reflectionAppend(object, clazz, builder, testTransients);
- }
- return builder.toHashCode();
- }
-
- /**
- * <p>Appends the fields and values defined by the given object of the
- * given <code>Class</code>.</p>
- *
- * @param object the object to append details of
- * @param clazz the class to append details of
- * @param builder the builder to append to
- * @param useTransients whether to use transient fields
- */
- private static void reflectionAppend(Object object, Class clazz, HashCodeBuilder builder, boolean useTransients) {
- Field[] fields = clazz.getDeclaredFields();
- AccessibleObject.setAccessible(fields, true);
- for (int i = 0; i < fields.length; i++) {
- Field f = fields[i];
- if ((f.getName().indexOf('$') == -1)
- && (useTransients || !Modifier.isTransient(f.getModifiers()))
- && (!Modifier.isStatic(f.getModifiers()))) {
- try {
- builder.append(f.get(object));
- } catch (IllegalAccessException e) {
- //this can't happen. Would get a Security exception instead
- //throw a runtime exception in case the impossible happens.
- throw new InternalError("Unexpected IllegalAccessException");
- }
- }
- }
- }
-
- //-------------------------------------------------------------------------
-
- /**
- * <p>Adds the result of super.hashCode() to this builder.</p>
- *
- * @param superHashCode the result of calling <code>super.hashCode()</code>
- * @return this HashCodeBuilder, used to chain calls.
- * @since 2.0
- */
- public HashCodeBuilder appendSuper(int superHashCode) {
- iTotal = iTotal * iConstant + superHashCode;
- return this;
- }
-
- //-------------------------------------------------------------------------
-
- /**
- * <p>Append a <code>hashCode</code> for an <code>Object</code>.</p>
- *
- * @param object the Object to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(Object object) {
- if (object == null) {
- iTotal = iTotal * iConstant;
-
- } else {
- if (object.getClass().isArray() == false) {
- //the simple case, not an array, just the element
- iTotal = iTotal * iConstant + object.hashCode();
-
- } else {
- //'Switch' on type of array, to dispatch to the correct handler
- // This handles multi dimensional arrays
- if (object instanceof long[]) {
- append((long[]) object);
- } else if (object instanceof int[]) {
- append((int[]) object);
- } else if (object instanceof short[]) {
- append((short[]) object);
- } else if (object instanceof char[]) {
- append((char[]) object);
- } else if (object instanceof byte[]) {
- append((byte[]) object);
- } else if (object instanceof double[]) {
- append((double[]) object);
- } else if (object instanceof float[]) {
- append((float[]) object);
- } else if (object instanceof boolean[]) {
- append((boolean[]) object);
- } else {
- // Not an array of primitives
- append((Object[]) object);
- }
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>long</code>.</p>
- *
- * @param value the long to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(long value) {
- iTotal = iTotal * iConstant + ((int) (value ^ (value >> 32)));
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for an <code>int</code>.</p>
- *
- * @param value the int to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(int value) {
- iTotal = iTotal * iConstant + value;
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>short</code>.</p>
- *
- * @param value the short to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(short value) {
- iTotal = iTotal * iConstant + value;
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>char</code>.</p>
- *
- * @param value the char to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(char value) {
- iTotal = iTotal * iConstant + value;
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>byte</code>.</p>
- *
- * @param value the byte to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(byte value) {
- iTotal = iTotal * iConstant + value;
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>double</code>.</p>
- *
- * @param value the double to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(double value) {
- return append(Double.doubleToLongBits(value));
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>float</code>.</p>
- *
- * @param value the float to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(float value) {
- iTotal = iTotal * iConstant + Float.floatToIntBits(value);
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>boolean</code>.</p>
- *
- * @param value the boolean to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(boolean value) {
- iTotal = iTotal * iConstant + (value ? 0 : 1);
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for an <code>Object</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(Object[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>long</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(long[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for an <code>int</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(int[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>short</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(short[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>char</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(char[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>byte</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(byte[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>double</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(double[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>float</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(float[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Append a <code>hashCode</code> for a <code>boolean</code> array.</p>
- *
- * @param array the array to add to the <code>hashCode</code>
- * @return this
- */
- public HashCodeBuilder append(boolean[] array) {
- if (array == null) {
- iTotal = iTotal * iConstant;
- } else {
- for (int i = 0; i < array.length; i++) {
- append(array[i]);
- }
- }
- return this;
- }
-
- /**
- * <p>Return the computed <code>hashCode</code>.</p>
- *
- * @return <code>hashCode</code> based on the fields appended
- */
- public int toHashCode() {
- return iTotal;
- }
-
- }