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Posted to dev@commons.apache.org by sc...@apache.org on 2002/09/13 00:00:00 UTC
cvs commit: jakarta-commons/lang/src/java/org/apache/commons/lang/builder EqualsBuilder.java
scolebourne 2002/09/12 15:00:00
Added: lang/src/java/org/apache/commons/lang/builder
EqualsBuilder.java
Log:
Added code from Steve Downey,
with some formatting changes and minor bug fixes
Revision Changes Path
1.1 jakarta-commons/lang/src/java/org/apache/commons/lang/builder/EqualsBuilder.java
Index: EqualsBuilder.java
===================================================================
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2002 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"
* 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.Field;
import java.lang.reflect.Modifier;
/**
* <code>Equals</code> generation routines.
* <p>
* This class provides methods to build a good equals method for any class.
* It follows rules laid out in Effective Java, 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>
* 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>
* 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>
* Typical use for the code is as follows:
* <code>
* public boolean equals(Object o) {
* if (!o instanceof MyClass) {
* return false;
* }
* MyClass rhs = (MyClass) o;
* return new EqualsBuilder()
* .test(field1, rhs.field1)
* .test(field2, rhs.field2)
* .test(field3, rhs.field3)
* .isEquals();
* }
* </code>
* <p>
* Alternatively, there is a method that uses reflection to determine
* the fields to test. Because these fields are usually private, the method,
* <code>reflectionTest</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. It is also slower than testing
* explicitly.
* <p>
* A typical invocation for this method would look like:
* <code>
* public boolean equals(Object o) {
* return EqualsBuilder.reflectionEquals(this, obj);
* }
* </code>
*
* @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
* @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
* @version $Id: EqualsBuilder.java,v 1.1 2002/09/12 22:00:00 scolebourne Exp $
*/
public class EqualsBuilder {
/**
* If the fields tested are equals.
*/
protected boolean isEquals;
/**
* Constructor for EqualsBuilder.
* Starts off assuming that equals is true.
* @see java.lang.Object#Object()
*/
public EqualsBuilder() {
super();
isEquals = true;
}
//-------------------------------------------------------------------------
/**
* This method uses reflection to determine if the two object are equal.
* <p>
* It uses Field.setAccessible 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.
* It is also not as efficient as testing explicitly.
* Transient members will be not be tested, as they are likely derived
* fields, and not part of the value of the object.
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @return boolean - if the two objects have tested equals.
*/
public static boolean reflectionEquals(Object lhs, Object rhs) {
return reflectionEquals(lhs, rhs, false);
}
/**
* This method uses reflection to determine if the two object are equal.
* <p>
* It uses Field.setAccessible 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.
* It is also not as efficient as testing explicitly.
* If the TestTransients parameter is set to true, transient members will be
* tested, otherwise they are ignored, as they are likely derived fields, and
* not part of the value of the object.
*
* @param lhs - Left Hand Side
* @param rhs - Right Hand Side
* @param testTransients - whether to include transient fields
* @return boolean - if the two objects have tested equals.
*/
public static boolean reflectionEquals(Object lhs, Object rhs, boolean testTransients) {
if (lhs == rhs) {
return true;
}
if (lhs == null || rhs == null) {
return false;
}
Class c1 = lhs.getClass();
if (!c1.isInstance(rhs)) {
return false;
}
Field[] fields = c1.getDeclaredFields();
Field.setAccessible(fields, true);
EqualsBuilder equalsBuilder = new EqualsBuilder();
for (int i = 0; i < fields.length && equalsBuilder.isEquals; ++i) {
Field f = fields[i];
if (testTransients || !Modifier.isTransient(f.getModifiers())) {
try {
equalsBuilder.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");
}
}
}
return equalsBuilder.isEquals();
}
//-------------------------------------------------------------------------
/**
* Test if two <code>Object</code>s are equal using their <code>equals</code>
* method.
* @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;
}
/**
* Test if two <code>long</code>s are equal using ==.
* @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;
}
/**
* Test if two <code>int</code>s are equal using ==.
* @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;
}
/**
* Test if two <code>short</code>s are equal using ==.
* @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;
}
/**
* Test if two <code>char</code>s are equal using ==.
* @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;
}
/**
* Test if two <code>byte</code>s are equal using ==.
* @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;
}
/**
* Test if two <code>double</code>s are equal by testing that the
* pattern of bits returned by doubleToLong are equal. This handles NaNs,
* Infinties, and -0.0. It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.
* @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));
}
/**
* Test if two <code>float</code>s are equal byt testing that the
* pattern of bits returned by doubleToLong are equal. This handles NaNs,
* Infinties, and -0.0. It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.
* @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));
}
/**
* Test if two <code>booleans</code>s are equal using ==.
* @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;
}
/**
* Performs a deep comparison of two object arrays. This also will be
* called for the top level of multi-dimensional, ragged, and multi-typed
* arrays.
* @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;
}
/**
* Deep comparison of array of <code>long</code> Length and all values
* are compared. The method append(long, long) is used.
* @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;
}
/**
* Deep comparison of array of <code>int</code> Length and all values
* are compared. The method append(int, int) is used.
* @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;
}
/**
* Deep comparison of array of <code>short</code> Length and all values
* are compared. The method append(short, short) is used.
* @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;
}
/**
* Deep comparison of array of <code>char</code> Length and all values
* are compared. The method append(char, char) is used.
* @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;
}
/**
* Deep comparison of array of <code>byte</code> Length and all values
* are compared. The method append(byte, byte) is used.
* @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;
}
/**
* Deep comparison of array of <code>double</code> Length and all values
* are compared. The method append(double, double) is used.
* @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;
}
/**
* Deep comparison of array of <code>float</code> Length and all values
* are compared. The method append(float, float) is used.
* @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;
}
/**
* Deep comparison of array of <code>boolean</code> Length and all values
* are compared. The method append(boolean, boolean) is used.
* @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;
}
/**
* Return true if the fields that have been checked are all equal.
* @return boolean
*/
public boolean isEquals() {
return isEquals;
}
}
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