/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.lang.builder;
/**
* <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
* <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/>
* <p>Two Objects 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/>
* <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/>
* <p>Typical use for the code is as follows:</p>
* <pre>
* public boolean equals(Object obj) {
* if (obj instanceof MyClass == false) {
* return false;
* }
* if (this == obj) {
* return true;
* }
* MyClass rhs = (MyClass) obj;
* return new EqualsBuilder()
* .appendSuper(super.equals(obj))
* .append(field1, rhs.field1)
* .append(field2, rhs.field2)
* .append(field3, rhs.field3)
* .isEquals();
* }
* </pre>
* <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>reflectionEquals</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/>
* <p> A typical invocation for this method would look like:</p>
* <pre>
* public boolean equals(Object obj) {
* return EqualsBuilder.reflectionEquals(this, obj);
* }
* </pre>
*
* @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
* @author Stephen Colebourne
* @author Gary Gregory
* @author Pete Gieser
* @author Arun Mammen Thomas
* @version $Id: EqualsBuilder.java 437554 2006-08-28 06:21:41Z bayard $
* @since 1.0
*/
@SuppressWarnings("PointlessBooleanExpression")
public class EqualsBuilder {
/**
* If the fields tested are equals.
* The default value is <code>true</code>.
*/
private boolean isEquals = true;
/**
* <p>Constructor for EqualsBuilder.</p>
* <p/>
* <p>Starts off assuming that equals is <code>true</code>.</p>
*
* @see Object#equals(Object)
*/
public EqualsBuilder() {
// do nothing for now.
}
//-------------------------------------------------------------------------
/**
* <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.
* @since 2.0
*/
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 the left hand object
* @param rhs the right hand object
* @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) {
this.setEquals(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 if (lhs.getClass() != rhs.getClass()) {
// Here when we compare different dimensions, for example: a boolean[][] to a boolean[]
this.setEquals(false);
}
// 'Switch' on type of array, to dispatch to the correct handler
// This handles multi dimensional arrays of the same depth
else 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.
* </p>
*
* @param lhs the left hand <code>long</code>
* @param rhs the right hand <code>long</code>
* @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.</p>
*
* @param lhs the left hand <code>int</code>
* @param rhs the right hand <code>int</code>
* @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.</p>
*
* @param lhs the left hand <code>short</code>
* @param rhs the right hand <code>short</code>
* @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.</p>
*
* @param lhs the left hand <code>char</code>
* @param rhs the right hand <code>char</code>
* @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.</p>
*
* @param lhs the left hand <code>byte</code>
* @param rhs the right hand <code>byte</code>
* @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/>
* <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
* <p/>
* <p>It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.</p>
*
* @param lhs the left hand <code>double</code>
* @param rhs the right hand <code>double</code>
* @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/>
* <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
* <p/>
* <p>It is compatible with the hash code generated by
* <code>HashCodeBuilder</code>.</p>
*
* @param lhs the left hand <code>float</code>
* @param rhs the right hand <code>float</code>
* @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.</p>
*
* @param lhs the left hand <code>boolean</code>
* @param rhs the right hand <code>boolean</code>
* @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/>
* <p>This also will be called for the top level of
* multi-dimensional, ragged, and multi-typed arrays.</p>
*
* @param lhs the left hand <code>Object[]</code>
* @param rhs the right hand <code>Object[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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>long</code>. Length and all
* values are compared.</p>
* <p/>
* <p>The method {@link #append(long, long)} is used.</p>
*
* @param lhs the left hand <code>long[]</code>
* @param rhs the right hand <code>long[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(int, int)} is used.</p>
*
* @param lhs the left hand <code>int[]</code>
* @param rhs the right hand <code>int[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(short, short)} is used.</p>
*
* @param lhs the left hand <code>short[]</code>
* @param rhs the right hand <code>short[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(char, char)} is used.</p>
*
* @param lhs the left hand <code>char[]</code>
* @param rhs the right hand <code>char[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(byte, byte)} is used.</p>
*
* @param lhs the left hand <code>byte[]</code>
* @param rhs the right hand <code>byte[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(double, double)} is used.</p>
*
* @param lhs the left hand <code>double[]</code>
* @param rhs the right hand <code>double[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(float, float)} is used.</p>
*
* @param lhs the left hand <code>float[]</code>
* @param rhs the right hand <code>float[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(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/>
* <p>The method {@link #append(boolean, boolean)} is used.</p>
*
* @param lhs the left hand <code>boolean[]</code>
* @param rhs the right hand <code>boolean[]</code>
* @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) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
* <p>Returns <code>true</code> if the fields that have been checked
* are all equal.</p>
*
* @return boolean
*/
public boolean isEquals() {
return this.isEquals;
}
/**
* Sets the <code>isEquals</code> value.
*
* @param isEquals The value to set.
* @since 2.1
*/
protected void setEquals(boolean isEquals) {
this.isEquals = isEquals;
}
}