    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.lang3.builder;
    018
    019import java.lang.reflect.AccessibleObject;
    020import java.lang.reflect.Field;
    021import java.lang.reflect.Modifier;
    022import java.util.ArrayList;
    023import java.util.Collection;
    024import java.util.HashSet;
    025import java.util.List;
    026import java.util.Set;
    027
    028import org.apache.commons.lang3.ArrayUtils;
    029import org.apache.commons.lang3.ClassUtils;
    030import org.apache.commons.lang3.tuple.Pair;
    031
    032/**
    033 * <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
    034 *
    035 * <p> This class provides methods to build a good equals method for any
    036 * class. It follows rules laid out in
    037 * <a href="http://www.oracle.com/technetwork/java/effectivejava-136174.html">Effective Java</a>
    038 * , by Joshua Bloch. In particular the rule for comparing {@code doubles},
    039 * {@code floats}, and arrays can be tricky. Also, making sure that
    040 * {@code equals()} and {@code hashCode()} are consistent can be
    041 * difficult.</p>
    042 *
    043 * <p>Two Objects that compare as equals must generate the same hash code,
    044 * but two Objects with the same hash code do not have to be equal.</p>
    045 *
    046 * <p>All relevant fields should be included in the calculation of equals.
    047 * Derived fields may be ignored. In particular, any field used in
    048 * generating a hash code must be used in the equals method, and vice
    049 * versa.</p>
    050 *
    051 * <p>Typical use for the code is as follows:</p>
    052 * <pre>
    053 * public boolean equals(Object obj) {
    054 *   if (obj == null) { return false; }
    055 *   if (obj == this) { return true; }
    056 *   if (obj.getClass() != getClass()) {
    057 *     return false;
    058 *   }
    059 *   MyClass rhs = (MyClass) obj;
    060 *   return new EqualsBuilder()
    061 *                 .appendSuper(super.equals(obj))
    062 *                 .append(field1, rhs.field1)
    063 *                 .append(field2, rhs.field2)
    064 *                 .append(field3, rhs.field3)
    065 *                 .isEquals();
    066 *  }
    067 * </pre>
    068 *
    069 * <p> Alternatively, there is a method that uses reflection to determine
    070 * the fields to test. Because these fields are usually private, the method,
    071 * {@code reflectionEquals}, uses {@code AccessibleObject.setAccessible} to
    072 * change the visibility of the fields. This will fail under a security
    073 * manager, unless the appropriate permissions are set up correctly. It is
    074 * also slower than testing explicitly.  Non-primitive fields are compared using
    075 * {@code equals()}.</p>
    076 *
    077 * <p> A typical invocation for this method would look like:</p>
    078 * <pre>
    079 * public boolean equals(Object obj) {
    080 *   return EqualsBuilder.reflectionEquals(this, obj);
    081 * }
    082 * </pre>
    083 *
    084 * <p>The {@link EqualsExclude} annotation can be used to exclude fields from being
    085 * used by the {@code reflectionEquals} methods.</p>
    086 *
    087 * @since 1.0
    088 */
    089public class EqualsBuilder implements Builder<Boolean> {
    090
    091    /**
    092     * <p>
    093     * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
    094     * </p>
    095     *
    096     * @since 3.0
    097     */
    098    private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = new ThreadLocal<>();
    099
    100    /*
    101     * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
    102     * we are in the process of calculating.
    103     *
    104     * So we generate a one-to-one mapping from the original object to a new object.
    105     *
    106     * Now HashSet uses equals() to determine if two elements with the same hash code really
    107     * are equal, so we also need to ensure that the replacement objects are only equal
    108     * if the original objects are identical.
    109     *
    110     * The original implementation (2.4 and before) used the System.identityHashCode()
    111     * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
    112     *
    113     * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
    114     * to disambiguate the duplicate ids.
    115     */
    116
    117    /**
    118     * <p>
    119     * Returns the registry of object pairs being traversed by the reflection
    120     * methods in the current thread.
    121     * </p>
    122     *
    123     * @return Set the registry of objects being traversed
    124     * @since 3.0
    125     */
    126    static Set<Pair<IDKey, IDKey>> getRegistry() {
    127        return REGISTRY.get();
    128    }
    129
    130    /**
    131     * <p>
    132     * Converters value pair into a register pair.
    133     * </p>
    134     *
    135     * @param lhs {@code this} object
    136     * @param rhs the other object
    137     *
    138     * @return the pair
    139     */
    140    static Pair<IDKey, IDKey> getRegisterPair(final Object lhs, final Object rhs) {
    141        final IDKey left = new IDKey(lhs);
    142        final IDKey right = new IDKey(rhs);
    143        return Pair.of(left, right);
    144    }
    145
    146    /**
    147     * <p>
    148     * Returns {@code true} if the registry contains the given object pair.
    149     * Used by the reflection methods to avoid infinite loops.
    150     * Objects might be swapped therefore a check is needed if the object pair
    151     * is registered in given or swapped order.
    152     * </p>
    153     *
    154     * @param lhs {@code this} object to lookup in registry
    155     * @param rhs the other object to lookup on registry
    156     * @return boolean {@code true} if the registry contains the given object.
    157     * @since 3.0
    158     */
    159    static boolean isRegistered(final Object lhs, final Object rhs) {
    160        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
    161        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
    162        final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getRight(), pair.getLeft());
    163
    164        return registry != null
    165                && (registry.contains(pair) || registry.contains(swappedPair));
    166    }
    167
    168    /**
    169     * <p>
    170     * Registers the given object pair.
    171     * Used by the reflection methods to avoid infinite loops.
    172     * </p>
    173     *
    174     * @param lhs {@code this} object to register
    175     * @param rhs the other object to register
    176     */
    177    private static void register(final Object lhs, final Object rhs) {
    178        Set<Pair<IDKey, IDKey>> registry = getRegistry();
    179        if (registry == null) {
    180            registry = new HashSet<>();
    181            REGISTRY.set(registry);
    182        }
    183        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
    184        registry.add(pair);
    185    }
    186
    187    /**
    188     * <p>
    189     * Unregisters the given object pair.
    190     * </p>
    191     *
    192     * <p>
    193     * Used by the reflection methods to avoid infinite loops.
    194     *
    195     * @param lhs {@code this} object to unregister
    196     * @param rhs the other object to unregister
    197     * @since 3.0
    198     */
    199    private static void unregister(final Object lhs, final Object rhs) {
    200        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
    201        if (registry != null) {
    202            final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
    203            registry.remove(pair);
    204            if (registry.isEmpty()) {
    205                REGISTRY.remove();
    206            }
    207        }
    208    }
    209
    210    /**
    211     * If the fields tested are equals.
    212     * The default value is {@code true}.
    213     */
    214    private boolean isEquals = true;
    215
    216    private boolean testTransients;
    217    private boolean testRecursive;
    218    private List<Class<?>> bypassReflectionClasses;
    219    private Class<?> reflectUpToClass;
    220    private String[] excludeFields;
    221
    222    /**
    223     * <p>Constructor for EqualsBuilder.</p>
    224     *
    225     * <p>Starts off assuming that equals is {@code true}.</p>
    226     * @see Object#equals(Object)
    227     */
    228    public EqualsBuilder() {
    229        // set up default classes to bypass reflection for
    230        bypassReflectionClasses = new ArrayList<>();
    231        bypassReflectionClasses.add(String.class); //hashCode field being lazy but not transient
    232    }
    233
    234    //-------------------------------------------------------------------------
    235
    236    /**
    237     * Set whether to include transient fields when reflectively comparing objects.
    238     * @param testTransients whether to test transient fields
    239     * @return EqualsBuilder - used to chain calls.
    240     * @since 3.6
    241     */
    242    public EqualsBuilder setTestTransients(final boolean testTransients) {
    243        this.testTransients = testTransients;
    244        return this;
    245    }
    246
    247    /**
    248     * Set whether to test fields recursively, instead of using their equals method, when reflectively comparing objects.
    249     * String objects, which cache a hash value, are automatically excluded from recursive testing.
    250     * You may specify other exceptions by calling {@link #setBypassReflectionClasses(List)}.
    251     * @param testRecursive whether to do a recursive test
    252     * @return EqualsBuilder - used to chain calls.
    253     * @see #setBypassReflectionClasses(List)
    254     * @since 3.6
    255     */
    256    public EqualsBuilder setTestRecursive(final boolean testRecursive) {
    257        this.testRecursive = testRecursive;
    258        return this;
    259    }
    260
    261    /**
    262     * <p>Set {@code Class}es whose instances should be compared by calling their {@code equals}
    263     * although being in recursive mode. So the fields of theses classes will not be compared recursively by reflection.</p>
    264     *
    265     * <p>Here you should name classes having non-transient fields which are cache fields being set lazily.<br>
    266     * Prominent example being {@link String} class with its hash code cache field. Due to the importance
    267     * of the {@code String} class, it is included in the default bypasses classes. Usually, if you use
    268     * your own set of classes here, remember to include {@code String} class, too.</p>
    269     * @param bypassReflectionClasses  classes to bypass reflection test
    270     * @return EqualsBuilder - used to chain calls.
    271     * @see #setTestRecursive(boolean)
    272     * @since 3.8
    273     */
    274    public EqualsBuilder setBypassReflectionClasses(final List<Class<?>> bypassReflectionClasses) {
    275        this.bypassReflectionClasses = bypassReflectionClasses;
    276        return this;
    277    }
    278
    279    /**
    280     * Set the superclass to reflect up to at reflective tests.
    281     * @param reflectUpToClass the super class to reflect up to
    282     * @return EqualsBuilder - used to chain calls.
    283     * @since 3.6
    284     */
    285    public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass) {
    286        this.reflectUpToClass = reflectUpToClass;
    287        return this;
    288    }
    289
    290    /**
    291     * Set field names to be excluded by reflection tests.
    292     * @param excludeFields the fields to exclude
    293     * @return EqualsBuilder - used to chain calls.
    294     * @since 3.6
    295     */
    296    public EqualsBuilder setExcludeFields(final String... excludeFields) {
    297        this.excludeFields = excludeFields;
    298        return this;
    299    }
    300
    301
    302    /**
    303     * <p>This method uses reflection to determine if the two {@code Object}s
    304     * are equal.</p>
    305     *
    306     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    307     * fields. This means that it will throw a security exception if run under
    308     * a security manager, if the permissions are not set up correctly. It is also
    309     * not as efficient as testing explicitly. Non-primitive fields are compared using
    310     * {@code equals()}.</p>
    311     *
    312     * <p>Transient members will be not be tested, as they are likely derived
    313     * fields, and not part of the value of the Object.</p>
    314     *
    315     * <p>Static fields will not be tested. Superclass fields will be included.</p>
    316     *
    317     * @param lhs  {@code this} object
    318     * @param rhs  the other object
    319     * @param excludeFields  Collection of String field names to exclude from testing
    320     * @return {@code true} if the two Objects have tested equals.
    321     *
    322     * @see EqualsExclude
    323     */
    324    public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
    325        return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
    326    }
    327
    328    /**
    329     * <p>This method uses reflection to determine if the two {@code Object}s
    330     * are equal.</p>
    331     *
    332     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    333     * fields. This means that it will throw a security exception if run under
    334     * a security manager, if the permissions are not set up correctly. It is also
    335     * not as efficient as testing explicitly. Non-primitive fields are compared using
    336     * {@code equals()}.</p>
    337     *
    338     * <p>Transient members will be not be tested, as they are likely derived
    339     * fields, and not part of the value of the Object.</p>
    340     *
    341     * <p>Static fields will not be tested. Superclass fields will be included.</p>
    342     *
    343     * @param lhs  {@code this} object
    344     * @param rhs  the other object
    345     * @param excludeFields  array of field names to exclude from testing
    346     * @return {@code true} if the two Objects have tested equals.
    347     *
    348     * @see EqualsExclude
    349     */
    350    public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
    351        return reflectionEquals(lhs, rhs, false, null, excludeFields);
    352    }
    353
    354    /**
    355     * <p>This method uses reflection to determine if the two {@code Object}s
    356     * are equal.</p>
    357     *
    358     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    359     * fields. This means that it will throw a security exception if run under
    360     * a security manager, if the permissions are not set up correctly. It is also
    361     * not as efficient as testing explicitly. Non-primitive fields are compared using
    362     * {@code equals()}.</p>
    363     *
    364     * <p>If the TestTransients parameter is set to {@code true}, transient
    365     * members will be tested, otherwise they are ignored, as they are likely
    366     * derived fields, and not part of the value of the {@code Object}.</p>
    367     *
    368     * <p>Static fields will not be tested. Superclass fields will be included.</p>
    369     *
    370     * @param lhs  {@code this} object
    371     * @param rhs  the other object
    372     * @param testTransients  whether to include transient fields
    373     * @return {@code true} if the two Objects have tested equals.
    374     *
    375     * @see EqualsExclude
    376     */
    377    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
    378        return reflectionEquals(lhs, rhs, testTransients, null);
    379    }
    380
    381    /**
    382     * <p>This method uses reflection to determine if the two {@code Object}s
    383     * are equal.</p>
    384     *
    385     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    386     * fields. This means that it will throw a security exception if run under
    387     * a security manager, if the permissions are not set up correctly. It is also
    388     * not as efficient as testing explicitly. Non-primitive fields are compared using
    389     * {@code equals()}.</p>
    390     *
    391     * <p>If the testTransients parameter is set to {@code true}, transient
    392     * members will be tested, otherwise they are ignored, as they are likely
    393     * derived fields, and not part of the value of the {@code Object}.</p>
    394     *
    395     * <p>Static fields will not be included. Superclass fields will be appended
    396     * up to and including the specified superclass. A null superclass is treated
    397     * as java.lang.Object.</p>
    398     *
    399     * @param lhs  {@code this} object
    400     * @param rhs  the other object
    401     * @param testTransients  whether to include transient fields
    402     * @param reflectUpToClass  the superclass to reflect up to (inclusive),
    403     *  may be {@code null}
    404     * @param excludeFields  array of field names to exclude from testing
    405     * @return {@code true} if the two Objects have tested equals.
    406     *
    407     * @see EqualsExclude
    408     * @since 2.0
    409     */
    410    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
    411            final String... excludeFields) {
    412        return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
    413    }
    414
    415    /**
    416     * <p>This method uses reflection to determine if the two {@code Object}s
    417     * are equal.</p>
    418     *
    419     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    420     * fields. This means that it will throw a security exception if run under
    421     * a security manager, if the permissions are not set up correctly. It is also
    422     * not as efficient as testing explicitly. Non-primitive fields are compared using
    423     * {@code equals()}.</p>
    424     *
    425     * <p>If the testTransients parameter is set to {@code true}, transient
    426     * members will be tested, otherwise they are ignored, as they are likely
    427     * derived fields, and not part of the value of the {@code Object}.</p>
    428     *
    429     * <p>Static fields will not be included. Superclass fields will be appended
    430     * up to and including the specified superclass. A null superclass is treated
    431     * as java.lang.Object.</p>
    432     *
    433     * <p>If the testRecursive parameter is set to {@code true}, non primitive
    434     * (and non primitive wrapper) field types will be compared by
    435     * {@code EqualsBuilder} recursively instead of invoking their
    436     * {@code equals()} method. Leading to a deep reflection equals test.
    437     *
    438     * @param lhs  {@code this} object
    439     * @param rhs  the other object
    440     * @param testTransients  whether to include transient fields
    441     * @param reflectUpToClass  the superclass to reflect up to (inclusive),
    442     *  may be {@code null}
    443     * @param testRecursive  whether to call reflection equals on non primitive
    444     *  fields recursively.
    445     * @param excludeFields  array of field names to exclude from testing
    446     * @return {@code true} if the two Objects have tested equals.
    447     *
    448     * @see EqualsExclude
    449     * @since 3.6
    450     */
    451    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
    452            final boolean testRecursive, final String... excludeFields) {
    453        if (lhs == rhs) {
    454            return true;
    455        }
    456        if (lhs == null || rhs == null) {
    457            return false;
    458        }
    459        return new EqualsBuilder()
    460                    .setExcludeFields(excludeFields)
    461                    .setReflectUpToClass(reflectUpToClass)
    462                    .setTestTransients(testTransients)
    463                    .setTestRecursive(testRecursive)
    464                    .reflectionAppend(lhs, rhs)
    465                    .isEquals();
    466    }
    467
    468    /**
    469     * <p>Tests if two {@code objects} by using reflection.</p>
    470     *
    471     * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
    472     * fields. This means that it will throw a security exception if run under
    473     * a security manager, if the permissions are not set up correctly. It is also
    474     * not as efficient as testing explicitly. Non-primitive fields are compared using
    475     * {@code equals()}.</p>
    476     *
    477     * <p>If the testTransients field is set to {@code true}, transient
    478     * members will be tested, otherwise they are ignored, as they are likely
    479     * derived fields, and not part of the value of the {@code Object}.</p>
    480     *
    481     * <p>Static fields will not be included. Superclass fields will be appended
    482     * up to and including the specified superclass in field {@code reflectUpToClass}.
    483     * A null superclass is treated as java.lang.Object.</p>
    484     *
    485     * <p>Field names listed in field {@code excludeFields} will be ignored.</p>
    486     *
    487     * <p>If either class of the compared objects is contained in
    488     * {@code bypassReflectionClasses}, both objects are compared by calling
    489     * the equals method of the left hand object with the right hand object as an argument.</p>
    490     *
    491     * @param lhs  the left hand object
    492     * @param rhs  the left hand object
    493     * @return EqualsBuilder - used to chain calls.
    494     */
    495    public EqualsBuilder reflectionAppend(final Object lhs, final Object rhs) {
    496        if (!isEquals) {
    497            return this;
    498        }
    499        if (lhs == rhs) {
    500            return this;
    501        }
    502        if (lhs == null || rhs == null) {
    503            isEquals = false;
    504            return this;
    505        }
    506
    507        // Find the leaf class since there may be transients in the leaf
    508        // class or in classes between the leaf and root.
    509        // If we are not testing transients or a subclass has no ivars,
    510        // then a subclass can test equals to a superclass.
    511        final Class<?> lhsClass = lhs.getClass();
    512        final Class<?> rhsClass = rhs.getClass();
    513        Class<?> testClass;
    514        if (lhsClass.isInstance(rhs)) {
    515            testClass = lhsClass;
    516            if (!rhsClass.isInstance(lhs)) {
    517                // rhsClass is a subclass of lhsClass
    518                testClass = rhsClass;
    519            }
    520        } else if (rhsClass.isInstance(lhs)) {
    521            testClass = rhsClass;
    522            if (!lhsClass.isInstance(rhs)) {
    523                // lhsClass is a subclass of rhsClass
    524                testClass = lhsClass;
    525            }
    526        } else {
    527            // The two classes are not related.
    528            isEquals = false;
    529            return this;
    530        }
    531
    532        try {
    533            if (testClass.isArray()) {
    534                append(lhs, rhs);
    535            } else //If either class is being excluded, call normal object equals method on lhsClass.
    536            if (bypassReflectionClasses != null
    537                    && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))) {
    538                isEquals = lhs.equals(rhs);
    539            } else {
    540                reflectionAppend(lhs, rhs, testClass);
    541                while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
    542                    testClass = testClass.getSuperclass();
    543                    reflectionAppend(lhs, rhs, testClass);
    544                }
    545            }
    546        } catch (final IllegalArgumentException e) {
    547            // In this case, we tried to test a subclass vs. a superclass and
    548            // the subclass has ivars or the ivars are transient and
    549            // we are testing transients.
    550            // If a subclass has ivars that we are trying to test them, we get an
    551            // exception and we know that the objects are not equal.
    552            isEquals = false;
    553        }
    554        return this;
    555    }
    556
    557    /**
    558     * <p>Appends the fields and values defined by the given object of the
    559     * given Class.</p>
    560     *
    561     * @param lhs  the left hand object
    562     * @param rhs  the right hand object
    563     * @param clazz  the class to append details of
    564     */
    565    private void reflectionAppend(
    566        final Object lhs,
    567        final Object rhs,
    568        final Class<?> clazz) {
    569
    570        if (isRegistered(lhs, rhs)) {
    571            return;
    572        }
    573
    574        try {
    575            register(lhs, rhs);
    576            final Field[] fields = clazz.getDeclaredFields();
    577            AccessibleObject.setAccessible(fields, true);
    578            for (int i = 0; i < fields.length && isEquals; i++) {
    579                final Field f = fields[i];
    580                if (!ArrayUtils.contains(excludeFields, f.getName())
    581                    && !f.getName().contains("$")
    582                    && (testTransients || !Modifier.isTransient(f.getModifiers()))
    583                    && !Modifier.isStatic(f.getModifiers())
    584                    && !f.isAnnotationPresent(EqualsExclude.class)) {
    585                    try {
    586                        append(f.get(lhs), f.get(rhs));
    587                    } catch (final IllegalAccessException e) {
    588                        //this can't happen. Would get a Security exception instead
    589                        //throw a runtime exception in case the impossible happens.
    590                        throw new InternalError("Unexpected IllegalAccessException");
    591                    }
    592                }
    593            }
    594        } finally {
    595            unregister(lhs, rhs);
    596        }
    597    }
    598
    599    //-------------------------------------------------------------------------
    600
    601    /**
    602     * <p>Adds the result of {@code super.equals()} to this builder.</p>
    603     *
    604     * @param superEquals  the result of calling {@code super.equals()}
    605     * @return EqualsBuilder - used to chain calls.
    606     * @since 2.0
    607     */
    608    public EqualsBuilder appendSuper(final boolean superEquals) {
    609        if (!isEquals) {
    610            return this;
    611        }
    612        isEquals = superEquals;
    613        return this;
    614    }
    615
    616    //-------------------------------------------------------------------------
    617
    618    /**
    619     * <p>Test if two {@code Object}s are equal using either
    620     * #{@link #reflectionAppend(Object, Object)}, if object are non
    621     * primitives (or wrapper of primitives) or if field {@code testRecursive}
    622     * is set to {@code false}. Otherwise, using their
    623     * {@code equals} method.</p>
    624     *
    625     * @param lhs  the left hand object
    626     * @param rhs  the right hand object
    627     * @return EqualsBuilder - used to chain calls.
    628     */
    629    public EqualsBuilder append(final Object lhs, final Object rhs) {
    630        if (!isEquals) {
    631            return this;
    632        }
    633        if (lhs == rhs) {
    634            return this;
    635        }
    636        if (lhs == null || rhs == null) {
    637            this.setEquals(false);
    638            return this;
    639        }
    640        final Class<?> lhsClass = lhs.getClass();
    641        if (lhsClass.isArray()) {
    642            // factor out array case in order to keep method small enough
    643            // to be inlined
    644            appendArray(lhs, rhs);
    645        } else // The simple case, not an array, just test the element
    646        if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)) {
    647            reflectionAppend(lhs, rhs);
    648        } else {
    649            isEquals = lhs.equals(rhs);
    650        }
    651        return this;
    652    }
    653
    654    /**
    655     * <p>Test if an {@code Object} is equal to an array.</p>
    656     *
    657     * @param lhs  the left hand object, an array
    658     * @param rhs  the right hand object
    659     */
    660    private void appendArray(final Object lhs, final Object rhs) {
    661        // First we compare different dimensions, for example: a boolean[][] to a boolean[]
    662        // then we 'Switch' on type of array, to dispatch to the correct handler
    663        // This handles multi dimensional arrays of the same depth
    664        if (lhs.getClass() != rhs.getClass()) {
    665            this.setEquals(false);
    666        } else if (lhs instanceof long[]) {
    667            append((long[]) lhs, (long[]) rhs);
    668        } else if (lhs instanceof int[]) {
    669            append((int[]) lhs, (int[]) rhs);
    670        } else if (lhs instanceof short[]) {
    671            append((short[]) lhs, (short[]) rhs);
    672        } else if (lhs instanceof char[]) {
    673            append((char[]) lhs, (char[]) rhs);
    674        } else if (lhs instanceof byte[]) {
    675            append((byte[]) lhs, (byte[]) rhs);
    676        } else if (lhs instanceof double[]) {
    677            append((double[]) lhs, (double[]) rhs);
    678        } else if (lhs instanceof float[]) {
    679            append((float[]) lhs, (float[]) rhs);
    680        } else if (lhs instanceof boolean[]) {
    681            append((boolean[]) lhs, (boolean[]) rhs);
    682        } else {
    683            // Not an array of primitives
    684            append((Object[]) lhs, (Object[]) rhs);
    685        }
    686    }
    687
    688    /**
    689     * <p>
    690     * Test if two {@code long} s are equal.
    691     * </p>
    692     *
    693     * @param lhs
    694     *                  the left hand {@code long}
    695     * @param rhs
    696     *                  the right hand {@code long}
    697     * @return EqualsBuilder - used to chain calls.
    698     */
    699    public EqualsBuilder append(final long lhs, final long rhs) {
    700        if (!isEquals) {
    701            return this;
    702        }
    703        isEquals = lhs == rhs;
    704        return this;
    705    }
    706
    707    /**
    708     * <p>Test if two {@code int}s are equal.</p>
    709     *
    710     * @param lhs  the left hand {@code int}
    711     * @param rhs  the right hand {@code int}
    712     * @return EqualsBuilder - used to chain calls.
    713     */
    714    public EqualsBuilder append(final int lhs, final int rhs) {
    715        if (!isEquals) {
    716            return this;
    717        }
    718        isEquals = lhs == rhs;
    719        return this;
    720    }
    721
    722    /**
    723     * <p>Test if two {@code short}s are equal.</p>
    724     *
    725     * @param lhs  the left hand {@code short}
    726     * @param rhs  the right hand {@code short}
    727     * @return EqualsBuilder - used to chain calls.
    728     */
    729    public EqualsBuilder append(final short lhs, final short rhs) {
    730        if (!isEquals) {
    731            return this;
    732        }
    733        isEquals = lhs == rhs;
    734        return this;
    735    }
    736
    737    /**
    738     * <p>Test if two {@code char}s are equal.</p>
    739     *
    740     * @param lhs  the left hand {@code char}
    741     * @param rhs  the right hand {@code char}
    742     * @return EqualsBuilder - used to chain calls.
    743     */
    744    public EqualsBuilder append(final char lhs, final char rhs) {
    745        if (!isEquals) {
    746            return this;
    747        }
    748        isEquals = lhs == rhs;
    749        return this;
    750    }
    751
    752    /**
    753     * <p>Test if two {@code byte}s are equal.</p>
    754     *
    755     * @param lhs  the left hand {@code byte}
    756     * @param rhs  the right hand {@code byte}
    757     * @return EqualsBuilder - used to chain calls.
    758     */
    759    public EqualsBuilder append(final byte lhs, final byte rhs) {
    760        if (!isEquals) {
    761            return this;
    762        }
    763        isEquals = lhs == rhs;
    764        return this;
    765    }
    766
    767    /**
    768     * <p>Test if two {@code double}s are equal by testing that the
    769     * pattern of bits returned by {@code doubleToLong} are equal.</p>
    770     *
    771     * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
    772     *
    773     * <p>It is compatible with the hash code generated by
    774     * {@code HashCodeBuilder}.</p>
    775     *
    776     * @param lhs  the left hand {@code double}
    777     * @param rhs  the right hand {@code double}
    778     * @return EqualsBuilder - used to chain calls.
    779     */
    780    public EqualsBuilder append(final double lhs, final double rhs) {
    781        if (!isEquals) {
    782            return this;
    783        }
    784        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    785    }
    786
    787    /**
    788     * <p>Test if two {@code float}s are equal by testing that the
    789     * pattern of bits returned by doubleToLong are equal.</p>
    790     *
    791     * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
    792     *
    793     * <p>It is compatible with the hash code generated by
    794     * {@code HashCodeBuilder}.</p>
    795     *
    796     * @param lhs  the left hand {@code float}
    797     * @param rhs  the right hand {@code float}
    798     * @return EqualsBuilder - used to chain calls.
    799     */
    800    public EqualsBuilder append(final float lhs, final float rhs) {
    801        if (!isEquals) {
    802            return this;
    803        }
    804        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    805    }
    806
    807    /**
    808     * <p>Test if two {@code booleans}s are equal.</p>
    809     *
    810     * @param lhs  the left hand {@code boolean}
    811     * @param rhs  the right hand {@code boolean}
    812     * @return EqualsBuilder - used to chain calls.
    813      */
    814    public EqualsBuilder append(final boolean lhs, final boolean rhs) {
    815        if (!isEquals) {
    816            return this;
    817        }
    818        isEquals = lhs == rhs;
    819        return this;
    820    }
    821
    822    /**
    823     * <p>Performs a deep comparison of two {@code Object} arrays.</p>
    824     *
    825     * <p>This also will be called for the top level of
    826     * multi-dimensional, ragged, and multi-typed arrays.</p>
    827     *
    828     * <p>Note that this method does not compare the type of the arrays; it only
    829     * compares the contents.</p>
    830     *
    831     * @param lhs  the left hand {@code Object[]}
    832     * @param rhs  the right hand {@code Object[]}
    833     * @return EqualsBuilder - used to chain calls.
    834     */
    835    public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
    836        if (!isEquals) {
    837            return this;
    838        }
    839        if (lhs == rhs) {
    840            return this;
    841        }
    842        if (lhs == null || rhs == null) {
    843            this.setEquals(false);
    844            return this;
    845        }
    846        if (lhs.length != rhs.length) {
    847            this.setEquals(false);
    848            return this;
    849        }
    850        for (int i = 0; i < lhs.length && isEquals; ++i) {
    851            append(lhs[i], rhs[i]);
    852        }
    853        return this;
    854    }
    855
    856    /**
    857     * <p>Deep comparison of array of {@code long}. Length and all
    858     * values are compared.</p>
    859     *
    860     * <p>The method {@link #append(long, long)} is used.</p>
    861     *
    862     * @param lhs  the left hand {@code long[]}
    863     * @param rhs  the right hand {@code long[]}
    864     * @return EqualsBuilder - used to chain calls.
    865     */
    866    public EqualsBuilder append(final long[] lhs, final long[] rhs) {
    867        if (!isEquals) {
    868            return this;
    869        }
    870        if (lhs == rhs) {
    871            return this;
    872        }
    873        if (lhs == null || rhs == null) {
    874            this.setEquals(false);
    875            return this;
    876        }
    877        if (lhs.length != rhs.length) {
    878            this.setEquals(false);
    879            return this;
    880        }
    881        for (int i = 0; i < lhs.length && isEquals; ++i) {
    882            append(lhs[i], rhs[i]);
    883        }
    884        return this;
    885    }
    886
    887    /**
    888     * <p>Deep comparison of array of {@code int}. Length and all
    889     * values are compared.</p>
    890     *
    891     * <p>The method {@link #append(int, int)} is used.</p>
    892     *
    893     * @param lhs  the left hand {@code int[]}
    894     * @param rhs  the right hand {@code int[]}
    895     * @return EqualsBuilder - used to chain calls.
    896     */
    897    public EqualsBuilder append(final int[] lhs, final int[] rhs) {
    898        if (!isEquals) {
    899            return this;
    900        }
    901        if (lhs == rhs) {
    902            return this;
    903        }
    904        if (lhs == null || rhs == null) {
    905            this.setEquals(false);
    906            return this;
    907        }
    908        if (lhs.length != rhs.length) {
    909            this.setEquals(false);
    910            return this;
    911        }
    912        for (int i = 0; i < lhs.length && isEquals; ++i) {
    913            append(lhs[i], rhs[i]);
    914        }
    915        return this;
    916    }
    917
    918    /**
    919     * <p>Deep comparison of array of {@code short}. Length and all
    920     * values are compared.</p>
    921     *
    922     * <p>The method {@link #append(short, short)} is used.</p>
    923     *
    924     * @param lhs  the left hand {@code short[]}
    925     * @param rhs  the right hand {@code short[]}
    926     * @return EqualsBuilder - used to chain calls.
    927     */
    928    public EqualsBuilder append(final short[] lhs, final short[] rhs) {
    929        if (!isEquals) {
    930            return this;
    931        }
    932        if (lhs == rhs) {
    933            return this;
    934        }
    935        if (lhs == null || rhs == null) {
    936            this.setEquals(false);
    937            return this;
    938        }
    939        if (lhs.length != rhs.length) {
    940            this.setEquals(false);
    941            return this;
    942        }
    943        for (int i = 0; i < lhs.length && isEquals; ++i) {
    944            append(lhs[i], rhs[i]);
    945        }
    946        return this;
    947    }
    948
    949    /**
    950     * <p>Deep comparison of array of {@code char}. Length and all
    951     * values are compared.</p>
    952     *
    953     * <p>The method {@link #append(char, char)} is used.</p>
    954     *
    955     * @param lhs  the left hand {@code char[]}
    956     * @param rhs  the right hand {@code char[]}
    957     * @return EqualsBuilder - used to chain calls.
    958     */
    959    public EqualsBuilder append(final char[] lhs, final char[] rhs) {
    960        if (!isEquals) {
    961            return this;
    962        }
    963        if (lhs == rhs) {
    964            return this;
    965        }
    966        if (lhs == null || rhs == null) {
    967            this.setEquals(false);
    968            return this;
    969        }
    970        if (lhs.length != rhs.length) {
    971            this.setEquals(false);
    972            return this;
    973        }
    974        for (int i = 0; i < lhs.length && isEquals; ++i) {
    975            append(lhs[i], rhs[i]);
    976        }
    977        return this;
    978    }
    979
    980    /**
    981     * <p>Deep comparison of array of {@code byte}. Length and all
    982     * values are compared.</p>
    983     *
    984     * <p>The method {@link #append(byte, byte)} is used.</p>
    985     *
    986     * @param lhs  the left hand {@code byte[]}
    987     * @param rhs  the right hand {@code byte[]}
    988     * @return EqualsBuilder - used to chain calls.
    989     */
    990    public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
    991        if (!isEquals) {
    992            return this;
    993        }
    994        if (lhs == rhs) {
    995            return this;
    996        }
    997        if (lhs == null || rhs == null) {
    998            this.setEquals(false);
    999            return this;
    1000        }
    1001        if (lhs.length != rhs.length) {
    1002            this.setEquals(false);
    1003            return this;
    1004        }
    1005        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1006            append(lhs[i], rhs[i]);
    1007        }
    1008        return this;
    1009    }
    1010
    1011    /**
    1012     * <p>Deep comparison of array of {@code double}. Length and all
    1013     * values are compared.</p>
    1014     *
    1015     * <p>The method {@link #append(double, double)} is used.</p>
    1016     *
    1017     * @param lhs  the left hand {@code double[]}
    1018     * @param rhs  the right hand {@code double[]}
    1019     * @return EqualsBuilder - used to chain calls.
    1020     */
    1021    public EqualsBuilder append(final double[] lhs, final double[] rhs) {
    1022        if (!isEquals) {
    1023            return this;
    1024        }
    1025        if (lhs == rhs) {
    1026            return this;
    1027        }
    1028        if (lhs == null || rhs == null) {
    1029            this.setEquals(false);
    1030            return this;
    1031        }
    1032        if (lhs.length != rhs.length) {
    1033            this.setEquals(false);
    1034            return this;
    1035        }
    1036        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1037            append(lhs[i], rhs[i]);
    1038        }
    1039        return this;
    1040    }
    1041
    1042    /**
    1043     * <p>Deep comparison of array of {@code float}. Length and all
    1044     * values are compared.</p>
    1045     *
    1046     * <p>The method {@link #append(float, float)} is used.</p>
    1047     *
    1048     * @param lhs  the left hand {@code float[]}
    1049     * @param rhs  the right hand {@code float[]}
    1050     * @return EqualsBuilder - used to chain calls.
    1051     */
    1052    public EqualsBuilder append(final float[] lhs, final float[] rhs) {
    1053        if (!isEquals) {
    1054            return this;
    1055        }
    1056        if (lhs == rhs) {
    1057            return this;
    1058        }
    1059        if (lhs == null || rhs == null) {
    1060            this.setEquals(false);
    1061            return this;
    1062        }
    1063        if (lhs.length != rhs.length) {
    1064            this.setEquals(false);
    1065            return this;
    1066        }
    1067        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1068            append(lhs[i], rhs[i]);
    1069        }
    1070        return this;
    1071    }
    1072
    1073    /**
    1074     * <p>Deep comparison of array of {@code boolean}. Length and all
    1075     * values are compared.</p>
    1076     *
    1077     * <p>The method {@link #append(boolean, boolean)} is used.</p>
    1078     *
    1079     * @param lhs  the left hand {@code boolean[]}
    1080     * @param rhs  the right hand {@code boolean[]}
    1081     * @return EqualsBuilder - used to chain calls.
    1082     */
    1083    public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
    1084        if (!isEquals) {
    1085            return this;
    1086        }
    1087        if (lhs == rhs) {
    1088            return this;
    1089        }
    1090        if (lhs == null || rhs == null) {
    1091            this.setEquals(false);
    1092            return this;
    1093        }
    1094        if (lhs.length != rhs.length) {
    1095            this.setEquals(false);
    1096            return this;
    1097        }
    1098        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1099            append(lhs[i], rhs[i]);
    1100        }
    1101        return this;
    1102    }
    1103
    1104    /**
    1105     * <p>Returns {@code true} if the fields that have been checked
    1106     * are all equal.</p>
    1107     *
    1108     * @return boolean
    1109     */
    1110    public boolean isEquals() {
    1111        return this.isEquals;
    1112    }
    1113
    1114    /**
    1115     * <p>Returns {@code true} if the fields that have been checked
    1116     * are all equal.</p>
    1117     *
    1118     * @return {@code true} if all of the fields that have been checked
    1119     *         are equal, {@code false} otherwise.
    1120     *
    1121     * @since 3.0
    1122     */
    1123    @Override
    1124    public Boolean build() {
    1125        return Boolean.valueOf(isEquals());
    1126    }
    1127
    1128    /**
    1129     * Sets the {@code isEquals} value.
    1130     *
    1131     * @param isEquals The value to set.
    1132     * @since 2.1
    1133     */
    1134    protected void setEquals(final boolean isEquals) {
    1135        this.isEquals = isEquals;
    1136    }
    1137
    1138    /**
    1139     * Reset the EqualsBuilder so you can use the same object again
    1140     * @since 2.5
    1141     */
    1142    public void reset() {
    1143        this.isEquals = true;
    1144    }
    1145}