/*
 * 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.lang3.builder;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.tuple.Pair;

Assists in implementing Object.equals(Object) methods.
 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 doubles,
floats, and arrays can be tricky. Also, making sure that
equals() and hashCode() are consistent can be
difficult.
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.
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.
Typical use for the code is as follows:
public boolean equals(Object obj) {
  if (obj == null) { return false; }
  if (obj == this) { return true; }
  if (obj.getClass() != getClass()) {
    return false;
  }
  MyClass rhs = (MyClass) obj;
  return new EqualsBuilder()
                .appendSuper(super.equals(obj))
                .append(field1, rhs.field1)
                .append(field2, rhs.field2)
                .append(field3, rhs.field3)
                .isEquals();
 }

 Alternatively, there is a method that uses reflection to determine
the fields to test. Because these fields are usually private, the method,
reflectionEquals, uses AccessibleObject.setAccessible 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.  Non-primitive fields are compared using
equals().
 A typical invocation for this method would look like:
public boolean equals(Object obj) {
  return EqualsBuilder.reflectionEquals(this, obj);
}

The EqualsExclude annotation can be used to exclude fields from being used by the reflectionEquals methods.
Since:
1.0/**
 * <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
 *
 * <p> This class provides methods to build a good equals method for any
 * class. It follows rules laid out in
 * <a href="http://www.oracle.com/technetwork/java/effectivejava-136174.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 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>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 obj) {
 *   if (obj == null) { return false; }
 *   if (obj == this) { return true; }
 *   if (obj.getClass() != getClass()) {
 *     return false;
 *   }
 *   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> 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.  Non-primitive fields are compared using
 * <code>equals()</code>.</p>
 *
 * <p> A typical invocation for this method would look like:</p>
 * <pre>
 * public boolean equals(Object obj) {
 *   return EqualsBuilder.reflectionEquals(this, obj);
 * }
 * </pre>
 *
 * <p>The {@link EqualsExclude} annotation can be used to exclude fields from being
 * used by the <code>reflectionEquals</code> methods.</p>
 *
 * @since 1.0
 */
public class EqualsBuilder implements Builder<Boolean> {

    

A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.

Since:
3.0/**
     * <p>
     * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
     * </p>
     *
     * @since 3.0
     */
    private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = new ThreadLocal<>();

    /*
     * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
     * we are in the process of calculating.
     *
     * So we generate a one-to-one mapping from the original object to a new object.
     *
     * Now HashSet uses equals() to determine if two elements with the same hash code really
     * are equal, so we also need to ensure that the replacement objects are only equal
     * if the original objects are identical.
     *
     * The original implementation (2.4 and before) used the System.identityHashCode()
     * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
     *
     * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
     * to disambiguate the duplicate ids.
     */

    

Returns the registry of object pairs being traversed by the reflection
methods in the current thread.

Returns:
Set the registry of objects being traversed
Since:
3.0/**
     * <p>
     * Returns the registry of object pairs being traversed by the reflection
     * methods in the current thread.
     * </p>
     *
     * @return Set the registry of objects being traversed
     * @since 3.0
     */
    static Set<Pair<IDKey, IDKey>> getRegistry() {
        return REGISTRY.get();
    }

    

Converters value pair into a register pair.

Params:
lhs – this object
rhs – the other object
Returns:
the pair/**
     * <p>
     * Converters value pair into a register pair.
     * </p>
     *
     * @param lhs <code>this</code> object
     * @param rhs the other object
     *
     * @return the pair
     */
    static Pair<IDKey, IDKey> getRegisterPair(final Object lhs, final Object rhs) {
        final IDKey left = new IDKey(lhs);
        final IDKey right = new IDKey(rhs);
        return Pair.of(left, right);
    }

    

Returns true if the registry contains the given object pair.
Used by the reflection methods to avoid infinite loops.
Objects might be swapped therefore a check is needed if the object pair
is registered in given or swapped order.

Params:
lhs – this object to lookup in registry
rhs – the other object to lookup on registry
Returns:
boolean true if the registry contains the given object.
Since:
3.0/**
     * <p>
     * Returns <code>true</code> if the registry contains the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * Objects might be swapped therefore a check is needed if the object pair
     * is registered in given or swapped order.
     * </p>
     *
     * @param lhs <code>this</code> object to lookup in registry
     * @param rhs the other object to lookup on registry
     * @return boolean <code>true</code> if the registry contains the given object.
     * @since 3.0
     */
    static boolean isRegistered(final Object lhs, final Object rhs) {
        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getRight(), pair.getLeft());

        return registry != null
                && (registry.contains(pair) || registry.contains(swappedPair));
    }

    

Registers the given object pair.
Used by the reflection methods to avoid infinite loops.

Params:
lhs – this object to register
rhs – the other object to register/**
     * <p>
     * Registers the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * </p>
     *
     * @param lhs <code>this</code> object to register
     * @param rhs the other object to register
     */
    private static void register(final Object lhs, final Object rhs) {
        Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry == null) {
            registry = new HashSet<>();
            REGISTRY.set(registry);
        }
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        registry.add(pair);
    }

    

Unregisters the given object pair.


Used by the reflection methods to avoid infinite loops.
Params:
lhs – this object to unregister
rhs – the other object to unregister
Since:
3.0/**
     * <p>
     * Unregisters the given object pair.
     * </p>
     *
     * <p>
     * Used by the reflection methods to avoid infinite loops.
     *
     * @param lhs <code>this</code> object to unregister
     * @param rhs the other object to unregister
     * @since 3.0
     */
    private static void unregister(final Object lhs, final Object rhs) {
        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry != null) {
            final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
            registry.remove(pair);
            if (registry.isEmpty()) {
                REGISTRY.remove();
            }
        }
    }

    
If the fields tested are equals.
The default value is true.
/**
     * If the fields tested are equals.
     * The default value is <code>true</code>.
     */
    private boolean isEquals = true;

    private boolean testTransients = false;
    private boolean testRecursive = false;
    private Class<?> reflectUpToClass = null;
    private String[] excludeFields = null;

    
Constructor for EqualsBuilder.
Starts off assuming that equals is true.
See Also:
equals.equals(Object)/**
     * <p>Constructor for EqualsBuilder.</p>
     *
     * <p>Starts off assuming that equals is <code>true</code>.</p>
     * @see Object#equals(Object)
     */
    public EqualsBuilder() {
        // do nothing for now.
    }

    //-------------------------------------------------------------------------

    
Set whether to include transient fields when reflectively comparing objects.
Params:
testTransients – whether to test transient fields
Returns:
EqualsBuilder - used to chain calls.
Since:
3.6/**
     * Set whether to include transient fields when reflectively comparing objects.
     * @param testTransients whether to test transient fields
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setTestTransients(final boolean testTransients) {
        this.testTransients = testTransients;
        return this;
    }

    
Set whether to include transient fields when reflectively comparing objects.
Params:
testRecursive –  whether to do a recursive test
Returns:
EqualsBuilder - used to chain calls.
Since:
3.6/**
     * Set whether to include transient fields when reflectively comparing objects.
     * @param testRecursive  whether to do a recursive test
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setTestRecursive(final boolean testRecursive) {
        this.testRecursive = testRecursive;
        return this;
    }

    
Set the superclass to reflect up to at reflective tests.
Params:
reflectUpToClass – the super class to reflect up to
Returns:
EqualsBuilder - used to chain calls.
Since:
3.6/**
     * Set the superclass to reflect up to at reflective tests.
     * @param reflectUpToClass the super class to reflect up to
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass) {
        this.reflectUpToClass = reflectUpToClass;
        return this;
    }

    
Set field names to be excluded by reflection tests.
Params:
excludeFields – the fields to exclude
Returns:
EqualsBuilder - used to chain calls.
Since:
3.6/**
     * Set field names to be excluded by reflection tests.
     * @param excludeFields the fields to exclude
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setExcludeFields(final String... excludeFields) {
        this.excludeFields = excludeFields;
        return this;
    }


    
This method uses reflection to determine if the two Objects
are equal.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
Transient members will be not be tested, as they are likely derived
fields, and not part of the value of the Object.
Static fields will not be tested. Superclass fields will be included.
Params:
lhs –  this object
rhs –  the other object
excludeFields –  Collection of String field names to exclude from testing
See Also:
EqualsExclude
Returns:
true if the two Objects have tested equals./**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</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
     * @param excludeFields  Collection of String field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
        return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
    }

    
This method uses reflection to determine if the two Objects
are equal.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
Transient members will be not be tested, as they are likely derived
fields, and not part of the value of the Object.
Static fields will not be tested. Superclass fields will be included.
Params:
lhs –  this object
rhs –  the other object
excludeFields –  array of field names to exclude from testing
See Also:
EqualsExclude
Returns:
true if the two Objects have tested equals./**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</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
     * @param excludeFields  array of field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
        return reflectionEquals(lhs, rhs, false, null, excludeFields);
    }

    
This method uses reflection to determine if the two Objects
are equal.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
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.
Static fields will not be tested. Superclass fields will be included.
Params:
lhs –  this object
rhs –  the other object
testTransients –  whether to include transient fields
See Also:
EqualsExclude
Returns:
true if the two Objects have tested equals./**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</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.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
        return reflectionEquals(lhs, rhs, testTransients, null);
    }

    
This method uses reflection to determine if the two Objects
are equal.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
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.
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.
Params:
lhs –  this object
rhs –  the other object
testTransients –  whether to include transient fields
reflectUpToClass –  the superclass to reflect up to (inclusive),
 may be null
excludeFields –  array of field names to exclude from testing
See Also:
EqualsExclude
Returns:
true if the two Objects have tested equals.
Since:
2.0/**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</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>
     * @param excludeFields  array of field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     *
     * @see EqualsExclude
     * @since 2.0
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
            final String... excludeFields) {
        return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
    }

    
This method uses reflection to determine if the two Objects
are equal.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
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.
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.
If the testRecursive parameter is set to true, non primitive
(and non primitive wrapper) field types will be compared by
EqualsBuilder recursively instead of invoking their
equals() method. Leading to a deep reflection equals test.
Params:
lhs –  this object
rhs –  the other object
testTransients –  whether to include transient fields
reflectUpToClass –  the superclass to reflect up to (inclusive),
 may be null
testRecursive –  whether to call reflection equals on non primitive
 fields recursively.
excludeFields –  array of field names to exclude from testing
See Also:
EqualsExclude
Returns:
true if the two Objects have tested equals.
Since:
3.6/**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</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>
     *
     * <p>If the testRecursive parameter is set to <code>true</code>, non primitive
     * (and non primitive wrapper) field types will be compared by
     * <code>EqualsBuilder</code> recursively instead of invoking their
     * <code>equals()</code> method. Leading to a deep reflection equals test.
     *
     * @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>
     * @param testRecursive  whether to call reflection equals on non primitive
     *  fields recursively.
     * @param excludeFields  array of field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     *
     * @see EqualsExclude
     * @since 3.6
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
            final boolean testRecursive, final String... excludeFields) {
        if (lhs == rhs) {
            return true;
        }
        if (lhs == null || rhs == null) {
            return false;
        }
        return new EqualsBuilder()
                    .setExcludeFields(excludeFields)
                    .setReflectUpToClass(reflectUpToClass)
                    .setTestTransients(testTransients)
                    .setTestRecursive(testRecursive)
                    .reflectionAppend(lhs, rhs)
                    .isEquals();
    }

    
Tests if two objects by using reflection.
It uses AccessibleObject.setAccessible 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. Non-primitive fields are compared using
equals().
If the testTransients field 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.
Static fields will not be included. Superclass fields will be appended
up to and including the specified superclass in field reflectUpToClass.
A null superclass is treated as java.lang.Object.
Field names listed in field excludeFields will be ignored.
Params:
lhs –  the left hand object
rhs –  the left hand object
Returns:
EqualsBuilder - used to chain calls./**
     * <p>Tests if two <code>objects</code> by using reflection.</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. Non-primitive fields are compared using
     * <code>equals()</code>.</p>
     *
     * <p>If the testTransients field 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 in field <code>reflectUpToClass</code>.
     * A null superclass is treated as java.lang.Object.</p>
     *
     * <p>Field names listed in field <code>excludeFields</code> will be ignored.</p>
     *
     * @param lhs  the left hand object
     * @param rhs  the left hand object
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder reflectionAppend(final Object lhs, final Object rhs) {
        if (!isEquals) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }

        // 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.
        final Class<?> lhsClass = lhs.getClass();
        final 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.
            isEquals = false;
            return this;
        }

        try {
            if (testClass.isArray()) {
                append(lhs, rhs);
            } else {
                reflectionAppend(lhs, rhs, testClass);
                while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
                    testClass = testClass.getSuperclass();
                    reflectionAppend(lhs, rhs, testClass);
                }
            }
        } catch (final 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.
            isEquals = false;
            return this;
        }
        return this;
    }

    
Appends the fields and values defined by the given object of the
given Class.
Params:
lhs –  the left hand object
rhs –  the right hand object
clazz –  the class to append details of/**
     * <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
     */
    private void reflectionAppend(
        final Object lhs,
        final Object rhs,
        final Class<?> clazz) {

        if (isRegistered(lhs, rhs)) {
            return;
        }

        try {
            register(lhs, rhs);
            final Field[] fields = clazz.getDeclaredFields();
            AccessibleObject.setAccessible(fields, true);
            for (int i = 0; i < fields.length && isEquals; i++) {
                final Field f = fields[i];
                if (!ArrayUtils.contains(excludeFields, f.getName())
                    && !f.getName().contains("$")
                    && (testTransients || !Modifier.isTransient(f.getModifiers()))
                    && !Modifier.isStatic(f.getModifiers())
                    && !f.isAnnotationPresent(EqualsExclude.class)) {
                    try {
                        append(f.get(lhs), f.get(rhs));
                    } catch (final 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");
                    }
                }
            }
        } finally {
            unregister(lhs, rhs);
        }
    }

    //-------------------------------------------------------------------------

    
Adds the result of super.equals() to this builder.
Params:
superEquals –  the result of calling super.equals()
Returns:
EqualsBuilder - used to chain calls.
Since:
2.0/**
     * <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(final boolean superEquals) {
        if (!isEquals) {
            return this;
        }
        isEquals = superEquals;
        return this;
    }

    //-------------------------------------------------------------------------

    
Test if two Objects are equal using either #reflectionAppend(Object, Object), if object are non primitives (or wrapper of primitives) or if field testRecursive
is set to false. Otherwise, using their
equals method.
Params:
lhs –  the left hand object
rhs –  the right hand object
Returns:
EqualsBuilder - used to chain calls./**
     * <p>Test if two <code>Object</code>s are equal using either
     * #{@link #reflectionAppend(Object, Object)}, if object are non
     * primitives (or wrapper of primitives) or if field <code>testRecursive</code>
     * is set to <code>false</code>. Otherwise, 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(final Object lhs, final Object rhs) {
        if (!isEquals) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        final Class<?> lhsClass = lhs.getClass();
        if (!lhsClass.isArray()) {
            // The simple case, not an array, just test the element
            if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)) {
                reflectionAppend(lhs, rhs);
            } else {
                isEquals = lhs.equals(rhs);
            }
        } else {
            // factor out array case in order to keep method small enough
            // to be inlined
            appendArray(lhs, rhs);
        }
        return this;
    }

    
Test if an Object is equal to an array.
Params:
lhs –  the left hand object, an array
rhs –  the right hand object/**
     * <p>Test if an <code>Object</code> is equal to an array.</p>
     *
     * @param lhs  the left hand object, an array
     * @param rhs  the right hand object
     */
    private void appendArray(final Object lhs, final Object rhs) {
        // First we compare different dimensions, for example: a boolean[][] to a boolean[]
        // then we 'Switch' on type of array, to dispatch to the correct handler
        // This handles multi dimensional arrays of the same depth
        if (lhs.getClass() != rhs.getClass()) {
            this.setEquals(false);
        } 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);
        }
    }

    

Test if two long s are equal.

Params:
lhs – 
                 the left hand long
rhs – 
                 the right hand long
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final long lhs, final long rhs) {
        if (!isEquals) {
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    
Test if two ints are equal.
Params:
lhs –  the left hand int
rhs –  the right hand int
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final int lhs, final int rhs) {
        if (!isEquals) {
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    
Test if two shorts are equal.
Params:
lhs –  the left hand short
rhs –  the right hand short
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final short lhs, final short rhs) {
        if (!isEquals) {
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    
Test if two chars are equal.
Params:
lhs –  the left hand char
rhs –  the right hand char
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final char lhs, final char rhs) {
        if (!isEquals) {
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    
Test if two bytes are equal.
Params:
lhs –  the left hand byte
rhs –  the right hand byte
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final byte lhs, final byte rhs) {
        if (!isEquals) {
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    
Test if two doubles are equal by testing that the
pattern of bits returned by doubleToLong are equal.
This handles NaNs, Infinities, and -0.0.
It is compatible with the hash code generated by
HashCodeBuilder.
Params:
lhs –  the left hand double
rhs –  the right hand double
Returns:
EqualsBuilder - used to chain calls./**
     * <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, Infinities, and <code>-0.0</code>.</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(final double lhs, final double rhs) {
        if (!isEquals) {
            return this;
        }
        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    }

    
Test if two floats are equal byt testing that the
pattern of bits returned by doubleToLong are equal.
This handles NaNs, Infinities, and -0.0.
It is compatible with the hash code generated by
HashCodeBuilder.
Params:
lhs –  the left hand float
rhs –  the right hand float
Returns:
EqualsBuilder - used to chain calls./**
     * <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, Infinities, and <code>-0.0</code>.</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(final float lhs, final float rhs) {
        if (!isEquals) {
            return this;
        }
        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    }

    
Test if two booleanss are equal.
Params:
lhs –  the left hand boolean
rhs –  the right hand boolean
Returns:
EqualsBuilder - used to chain calls./**
     * <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(final boolean lhs, final boolean rhs) {
        if (!isEquals) {
            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.
Note that this method does not compare the type of the arrays; it only
compares the contents.
Params:
lhs –  the left hand Object[]
rhs –  the right hand Object[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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>
     *
     * <p>Note that this method does not compare the type of the arrays; it only
     * compares the contents.</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(final Object[] lhs, final Object[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of long. Length and all
values are compared.
The method append(long, long) is used.
Params:
lhs –  the left hand long[]
rhs –  the right hand long[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>long[]</code>
     * @param rhs  the right hand <code>long[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final long[] lhs, final long[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of int. Length and all
values are compared.
The method append(int, int) is used.
Params:
lhs –  the left hand int[]
rhs –  the right hand int[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>int[]</code>
     * @param rhs  the right hand <code>int[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final int[] lhs, final int[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of short. Length and all
values are compared.
The method append(short, short) is used.
Params:
lhs –  the left hand short[]
rhs –  the right hand short[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>short[]</code>
     * @param rhs  the right hand <code>short[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final short[] lhs, final short[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of char. Length and all
values are compared.
The method append(char, char) is used.
Params:
lhs –  the left hand char[]
rhs –  the right hand char[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>char[]</code>
     * @param rhs  the right hand <code>char[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final char[] lhs, final char[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of byte. Length and all
values are compared.
The method append(byte, byte) is used.
Params:
lhs –  the left hand byte[]
rhs –  the right hand byte[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>byte[]</code>
     * @param rhs  the right hand <code>byte[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of double. Length and all
values are compared.
The method append(double, double) is used.
Params:
lhs –  the left hand double[]
rhs –  the right hand double[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>double[]</code>
     * @param rhs  the right hand <code>double[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final double[] lhs, final double[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of float. Length and all
values are compared.
The method append(float, float) is used.
Params:
lhs –  the left hand float[]
rhs –  the right hand float[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>float[]</code>
     * @param rhs  the right hand <code>float[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final float[] lhs, final float[] rhs) {
        if (!isEquals) {
            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;
    }

    
Deep comparison of array of boolean. Length and all
values are compared.
The method append(boolean, boolean) is used.
Params:
lhs –  the left hand boolean[]
rhs –  the right hand boolean[]
Returns:
EqualsBuilder - used to chain calls./**
     * <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  the left hand <code>boolean[]</code>
     * @param rhs  the right hand <code>boolean[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
        if (!isEquals) {
            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;
    }

    
Returns true if the fields that have been checked
are all equal.
Returns:
boolean/**
     * <p>Returns <code>true</code> if the fields that have been checked
     * are all equal.</p>
     *
     * @return boolean
     */
    public boolean isEquals() {
        return this.isEquals;
    }

    
Returns true if the fields that have been checked
are all equal.
Returns:
true if all of the fields that have been checked
        are equal, false otherwise.
Since:
3.0/**
     * <p>Returns <code>true</code> if the fields that have been checked
     * are all equal.</p>
     *
     * @return <code>true</code> if all of the fields that have been checked
     *         are equal, <code>false</code> otherwise.
     *
     * @since 3.0
     */
    @Override
    public Boolean build() {
        return Boolean.valueOf(isEquals());
    }

    
Sets the isEquals value.
Params:
isEquals – The value to set.
Since:
2.1/**
     * Sets the <code>isEquals</code> value.
     *
     * @param isEquals The value to set.
     * @since 2.1
     */
    protected void setEquals(final boolean isEquals) {
        this.isEquals = isEquals;
    }

    
Reset the EqualsBuilder so you can use the same object again
Since:
2.5/**
     * Reset the EqualsBuilder so you can use the same object again
     * @since 2.5
     */
    public void reset() {
        this.isEquals = true;
    }
}