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/* ====================================================================
* 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 acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements 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"
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* ====================================================================
*
* 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.Field;
import java.lang.reflect.Modifier;
/**
* <p><code>Equals</code> generation routines.</p>
*
* <p> This class provides methods to build a good equals method for any
* class. It follows rules laid out in
* <a href="http://java.sun.com/docs/books/effective/index.html">Effective Java</a>
* , by Joshua Bloch. In particular the rule for comparing <code>doubles</code>,
* <code>floats</code>, and arrays can be tricky. Also, making sure that
* <code>equals()</code> and <code>hashCode()</code> are consistent can be
* difficult.</p>
*
* <p>Two Object that compare as equals must generate the same hash code.
* But two Objects with the same hash code do not have to be equal.</p>
*
* <p>All relevant fields should be included in the calculation of equals.
* Derived fields may be ignored. In particular, any field used in
* generating a hash code must be used in the equals method, and vice
* versa.</p>
*
* <p>Typical use for the code is as follows:</p>
* <pre>
* public boolean equals(Object o) {
* if ( !(o instanceof MyClass) ) {
* return false;
* }
* MyClass rhs = (MyClass) o;
* return new EqualsBuilder()
* .appendSuper(super.equals(o))
* .append(field1, rhs.field1)
* .append(field2, rhs.field2)
* .append(field3, rhs.field3)
* .isEquals();
* }
* </pre>
*
* <p> Alternatively, there is a method that uses reflection to determine
* the fields to test. Because these fields are usually private, the method,
* <code>reflectionEquals</code>, uses <code>Field.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 boolean equals(Object o) {
* return EqualsBuilder.reflectionEquals(this, o);
* }
* </pre>
*
* @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
* @author Stephen Colebourne
* @author Gary Gregory
* @since 1.0
* @version $Id: EqualsBuilder.java,v 1.14 2003/07/14 22:25:03 bayard Exp $
*/
public class EqualsBuilder {
/**
* If the fields tested are equals.
*/
private boolean isEquals;
/**
* <p>Constructor for EqualsBuilder.</p>
*
* <p>Starts off assuming that equals is <code>true</code>.</p>
* @see java.lang.Object#Object()
*/
public EqualsBuilder() {
super();
isEquals = true;
}
//-------------------------------------------------------------------------
/**
* <p>This method uses reflection to determine if the two <code>Object</code>s
* are equal.</p>
*
* <p>It uses <code>Field.setAccessible</code> to gain access to private
* fields. This means that it will throw a security exception if run under
* a security manger, 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 tested, as they are likely derived
* fields, and not part of the value of the Object.</p>
*
* <p>Static fields will not be tested. Superclass fields will be included.</p>
*
* @param lhs <code>this</code> object
* @param rhs the other object
* @return <code>true</code> if the two Objects have tested equals.
*/
public static boolean reflectionEquals(Object lhs, Object rhs) {
return reflectionEquals(lhs, rhs, false, null);
}
/**
* <p>This method uses reflection to determine if the two <code>Object</code>s
* are equal.</p>
*
* <p>It uses <code>Field.setAccessible</code> to gain access to private
* fields. This means that it will throw a security exception if run under
* a security manger, 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 lhs <code>this</code> object
* @param rhs the other object
* @param testTransients whether to include transient fields
* @return <code>true</code> if the two Objects have tested equals.
*/
public static boolean reflectionEquals(Object lhs, Object rhs, boolean testTransients) {
return reflectionEquals(lhs, rhs, testTransients, null);
}
/**
* <p>This method uses reflection to determine if the two <code>Object</code>s
* are equal.</p>
*
* <p>It uses <code>Field.setAccessible</code> to gain access to private
* fields. This means that it will throw a security exception if run under
* a security manger, 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 appended
* up to and including the specified superclass. A null superclass is treated
* as java.lang.Object.</p>
*
* @param lhs <code>this</code> object
* @param rhs the other object
* @param testTransients whether to include transient fields
* @param reflectUpToClass the superclass to reflect up to (inclusive),
* may be <code>null</code>
* @return <code>true</code> if the two Objects have tested equals.
*/
public static boolean reflectionEquals(Object lhs, Object rhs, boolean testTransients, Class reflectUpToClass) {
if (lhs == rhs) {
return true;
}
if (lhs == null || rhs == null) {
return false;
}
// Find the leaf class since there may be transients in the leaf
// class or in classes between the leaf and root.
// If we are not testing transients or a subclass has no ivars,
// then a subclass can test equals to a superclass.
Class lhsClass = lhs.getClass();
Class rhsClass = rhs.getClass();
Class testClass;
if (lhsClass.isInstance(rhs)) {
testClass = lhsClass;
if (!rhsClass.isInstance(lhs)) {
// rhsClass is a subclass of lhsClass
testClass = rhsClass;
}
} else if (rhsClass.isInstance(lhs)) {
testClass = rhsClass;
if (!lhsClass.isInstance(rhs)) {
// lhsClass is a subclass of rhsClass
testClass = lhsClass;
}
} else {
// The two classes are not related.
return false;
}
EqualsBuilder equalsBuilder = new EqualsBuilder();
try {
reflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients);
while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
testClass = testClass.getSuperclass();
reflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients);
}
} catch (IllegalArgumentException e) {
// In this case, we tried to test a subclass vs. a superclass and
// the subclass has ivars or the ivars are transient and
// we are testing transients.
// If a subclass has ivars that we are trying to test them, we get an
// exception and we know that the objects are not equal.
return false;
}
return equalsBuilder.isEquals();
}
/**
* <p>Appends the fields and values defined by the given object of the
* given Class.</p>
*
* @param lhs the left hand object
* @param rhs the right hand object
* @param clazz the class to append details of
* @param builder the builder to append to
* @param useTransients whether to test transient fields
*/
private static void reflectionAppend(
Object lhs,
Object rhs,
Class clazz,
EqualsBuilder builder,
boolean useTransients) {
Field[] fields = clazz.getDeclaredFields();
Field.setAccessible(fields, true);
for (int i = 0; i < fields.length && builder.isEquals; i++) {
Field f = fields[i];
if ((f.getName().indexOf('$') == -1)
&& (useTransients || !Modifier.isTransient(f.getModifiers()))
&& (!Modifier.isStatic(f.getModifiers()))) {
try {
builder.append(f.get(lhs), f.get(rhs));
} 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 <code>super.equals()</code> to this builder.</p>
*
* @param superEquals the result of calling <code>super.equals()</code>
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder appendSuper(boolean superEquals) {
if (isEquals == false) {
return this;
}
isEquals = superEquals;
return this;
}
//-------------------------------------------------------------------------
/**
* <p>Test if two <code>Object</code>s are equal using their
* <code>equals</code> method.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(Object lhs, Object rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
Class lhsClass = lhs.getClass();
if (!lhsClass.isArray()) {
//the simple case, not an array, just test the element
isEquals = lhs.equals(rhs);
} else {
//'Switch' on type of array, to dispatch to the correct handler
// This handles multi dimensional arrays
if (lhs instanceof long[]) {
append((long[]) lhs, (long[]) rhs);
} else if (lhs instanceof int[]) {
append((int[]) lhs, (int[]) rhs);
} else if (lhs instanceof short[]) {
append((short[]) lhs, (short[]) rhs);
} else if (lhs instanceof char[]) {
append((char[]) lhs, (char[]) rhs);
} else if (lhs instanceof byte[]) {
append((byte[]) lhs, (byte[]) rhs);
} else if (lhs instanceof double[]) {
append((double[]) lhs, (double[]) rhs);
} else if (lhs instanceof float[]) {
append((float[]) lhs, (float[]) rhs);
} else if (lhs instanceof boolean[]) {
append((boolean[]) lhs, (boolean[]) rhs);
} else {
// Not an array of primitives
append((Object[]) lhs, (Object[]) rhs);
}
}
return this;
}
/**
* <p>Test if two <code>long</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(long lhs, long rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Test if two <code>int</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(int lhs, int rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Test if two <code>short</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(short lhs, short rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Test if two <code>char</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(char lhs, char rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Test if two <code>byte</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(byte lhs, byte rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Test if two <code>double</code>s are equal by testing that the
* pattern of bits returned by <code>doubleToLong</code> are equal.</p>
*
* <p>This handles NaNs, Infinties, and <code>-0.0</code>.</p>
*
* <p>It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(double lhs, double rhs) {
if (isEquals == false) {
return this;
}
return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
}
/**
* <p>Test if two <code>float</code>s are equal byt testing that the
* pattern of bits returned by doubleToLong are equal.</p>
*
* <p>This handles NaNs, Infinties, and <code>-0.0</code>.</p>
*
* <p>It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(float lhs, float rhs) {
if (isEquals == false) {
return this;
}
return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
}
/**
* <p>Test if two <code>booleans</code>s are equal using ==.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(boolean lhs, boolean rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
* <p>Performs a deep comparison of two <code>Object</code> arrays.</p>
*
* <p>This also will be called for the top level of
* multi-dimensional, ragged, and multi-typed arrays.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(Object[] lhs, Object[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
Class lhsClass = lhs[i].getClass();
if (!lhsClass.isInstance(rhs[i])) {
isEquals = false; //If the types don't match, not equal
break;
}
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>long</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(long, long)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(long[] lhs, long[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>int</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(int, int)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(int[] lhs, int[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>short</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(short, short)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(short[] lhs, short[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>char</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(char, char)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(char[] lhs, char[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>byte</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(byte, byte)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(byte[] lhs, byte[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>double</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(double, double)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(double[] lhs, double[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>float</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(float, float)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(float[] lhs, float[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Deep comparison of array of <code>boolean</code>. Length and all
* values are compared.</p>
*
* <p>The method {@link #append(boolean, boolean)} is used.</p>
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(boolean[] lhs, boolean[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
isEquals = false;
return this;
}
if (lhs.length != rhs.length) {
isEquals = false;
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Return <code>true</code> if the fields that have been checked
* are all equal.</p>
*
* @return boolean
*/
public boolean isEquals() {
return isEquals;
}
}