    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 = false;
    217    private boolean testRecursive = false;
    218    private List<Class<?>> bypassReflectionClasses;
    219    private Class<?> reflectUpToClass = null;
    220    private String[] excludeFields = null;
    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 {
    536                //If either class is being excluded, call normal object equals method on lhsClass.
    537                if (bypassReflectionClasses != null
    538                        && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))) {
    539                    isEquals = lhs.equals(rhs);
    540                } else {
    541                    reflectionAppend(lhs, rhs, testClass);
    542                    while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
    543                        testClass = testClass.getSuperclass();
    544                        reflectionAppend(lhs, rhs, testClass);
    545                    }
    546                }
    547            }
    548        } catch (final IllegalArgumentException e) {
    549            // In this case, we tried to test a subclass vs. a superclass and
    550            // the subclass has ivars or the ivars are transient and
    551            // we are testing transients.
    552            // If a subclass has ivars that we are trying to test them, we get an
    553            // exception and we know that the objects are not equal.
    554            isEquals = false;
    555            return this;
    556        }
    557        return this;
    558    }
    559
    560    /**
    561     * <p>Appends the fields and values defined by the given object of the
    562     * given Class.</p>
    563     *
    564     * @param lhs  the left hand object
    565     * @param rhs  the right hand object
    566     * @param clazz  the class to append details of
    567     */
    568    private void reflectionAppend(
    569        final Object lhs,
    570        final Object rhs,
    571        final Class<?> clazz) {
    572
    573        if (isRegistered(lhs, rhs)) {
    574            return;
    575        }
    576
    577        try {
    578            register(lhs, rhs);
    579            final Field[] fields = clazz.getDeclaredFields();
    580            AccessibleObject.setAccessible(fields, true);
    581            for (int i = 0; i < fields.length && isEquals; i++) {
    582                final Field f = fields[i];
    583                if (!ArrayUtils.contains(excludeFields, f.getName())
    584                    && !f.getName().contains("$")
    585                    && (testTransients || !Modifier.isTransient(f.getModifiers()))
    586                    && !Modifier.isStatic(f.getModifiers())
    587                    && !f.isAnnotationPresent(EqualsExclude.class)) {
    588                    try {
    589                        append(f.get(lhs), f.get(rhs));
    590                    } catch (final IllegalAccessException e) {
    591                        //this can't happen. Would get a Security exception instead
    592                        //throw a runtime exception in case the impossible happens.
    593                        throw new InternalError("Unexpected IllegalAccessException");
    594                    }
    595                }
    596            }
    597        } finally {
    598            unregister(lhs, rhs);
    599        }
    600    }
    601
    602    //-------------------------------------------------------------------------
    603
    604    /**
    605     * <p>Adds the result of {@code super.equals()} to this builder.</p>
    606     *
    607     * @param superEquals  the result of calling {@code super.equals()}
    608     * @return EqualsBuilder - used to chain calls.
    609     * @since 2.0
    610     */
    611    public EqualsBuilder appendSuper(final boolean superEquals) {
    612        if (!isEquals) {
    613            return this;
    614        }
    615        isEquals = superEquals;
    616        return this;
    617    }
    618
    619    //-------------------------------------------------------------------------
    620
    621    /**
    622     * <p>Test if two {@code Object}s are equal using either
    623     * #{@link #reflectionAppend(Object, Object)}, if object are non
    624     * primitives (or wrapper of primitives) or if field {@code testRecursive}
    625     * is set to {@code false}. Otherwise, using their
    626     * {@code equals} method.</p>
    627     *
    628     * @param lhs  the left hand object
    629     * @param rhs  the right hand object
    630     * @return EqualsBuilder - used to chain calls.
    631     */
    632    public EqualsBuilder append(final Object lhs, final Object rhs) {
    633        if (!isEquals) {
    634            return this;
    635        }
    636        if (lhs == rhs) {
    637            return this;
    638        }
    639        if (lhs == null || rhs == null) {
    640            this.setEquals(false);
    641            return this;
    642        }
    643        final Class<?> lhsClass = lhs.getClass();
    644        if (lhsClass.isArray()) {
    645            // factor out array case in order to keep method small enough
    646            // to be inlined
    647            appendArray(lhs, rhs);
    648        } else {
    649            // The simple case, not an array, just test the element
    650            if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)) {
    651                reflectionAppend(lhs, rhs);
    652            } else {
    653                isEquals = lhs.equals(rhs);
    654            }
    655        }
    656        return this;
    657    }
    658
    659    /**
    660     * <p>Test if an {@code Object} is equal to an array.</p>
    661     *
    662     * @param lhs  the left hand object, an array
    663     * @param rhs  the right hand object
    664     */
    665    private void appendArray(final Object lhs, final Object rhs) {
    666        // First we compare different dimensions, for example: a boolean[][] to a boolean[]
    667        // then we 'Switch' on type of array, to dispatch to the correct handler
    668        // This handles multi dimensional arrays of the same depth
    669        if (lhs.getClass() != rhs.getClass()) {
    670            this.setEquals(false);
    671        } else if (lhs instanceof long[]) {
    672            append((long[]) lhs, (long[]) rhs);
    673        } else if (lhs instanceof int[]) {
    674            append((int[]) lhs, (int[]) rhs);
    675        } else if (lhs instanceof short[]) {
    676            append((short[]) lhs, (short[]) rhs);
    677        } else if (lhs instanceof char[]) {
    678            append((char[]) lhs, (char[]) rhs);
    679        } else if (lhs instanceof byte[]) {
    680            append((byte[]) lhs, (byte[]) rhs);
    681        } else if (lhs instanceof double[]) {
    682            append((double[]) lhs, (double[]) rhs);
    683        } else if (lhs instanceof float[]) {
    684            append((float[]) lhs, (float[]) rhs);
    685        } else if (lhs instanceof boolean[]) {
    686            append((boolean[]) lhs, (boolean[]) rhs);
    687        } else {
    688            // Not an array of primitives
    689            append((Object[]) lhs, (Object[]) rhs);
    690        }
    691    }
    692
    693    /**
    694     * <p>
    695     * Test if two {@code long} s are equal.
    696     * </p>
    697     *
    698     * @param lhs
    699     *                  the left hand {@code long}
    700     * @param rhs
    701     *                  the right hand {@code long}
    702     * @return EqualsBuilder - used to chain calls.
    703     */
    704    public EqualsBuilder append(final long lhs, final long rhs) {
    705        if (!isEquals) {
    706            return this;
    707        }
    708        isEquals = lhs == rhs;
    709        return this;
    710    }
    711
    712    /**
    713     * <p>Test if two {@code int}s are equal.</p>
    714     *
    715     * @param lhs  the left hand {@code int}
    716     * @param rhs  the right hand {@code int}
    717     * @return EqualsBuilder - used to chain calls.
    718     */
    719    public EqualsBuilder append(final int lhs, final int rhs) {
    720        if (!isEquals) {
    721            return this;
    722        }
    723        isEquals = lhs == rhs;
    724        return this;
    725    }
    726
    727    /**
    728     * <p>Test if two {@code short}s are equal.</p>
    729     *
    730     * @param lhs  the left hand {@code short}
    731     * @param rhs  the right hand {@code short}
    732     * @return EqualsBuilder - used to chain calls.
    733     */
    734    public EqualsBuilder append(final short lhs, final short rhs) {
    735        if (!isEquals) {
    736            return this;
    737        }
    738        isEquals = lhs == rhs;
    739        return this;
    740    }
    741
    742    /**
    743     * <p>Test if two {@code char}s are equal.</p>
    744     *
    745     * @param lhs  the left hand {@code char}
    746     * @param rhs  the right hand {@code char}
    747     * @return EqualsBuilder - used to chain calls.
    748     */
    749    public EqualsBuilder append(final char lhs, final char rhs) {
    750        if (!isEquals) {
    751            return this;
    752        }
    753        isEquals = lhs == rhs;
    754        return this;
    755    }
    756
    757    /**
    758     * <p>Test if two {@code byte}s are equal.</p>
    759     *
    760     * @param lhs  the left hand {@code byte}
    761     * @param rhs  the right hand {@code byte}
    762     * @return EqualsBuilder - used to chain calls.
    763     */
    764    public EqualsBuilder append(final byte lhs, final byte rhs) {
    765        if (!isEquals) {
    766            return this;
    767        }
    768        isEquals = lhs == rhs;
    769        return this;
    770    }
    771
    772    /**
    773     * <p>Test if two {@code double}s are equal by testing that the
    774     * pattern of bits returned by {@code doubleToLong} are equal.</p>
    775     *
    776     * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
    777     *
    778     * <p>It is compatible with the hash code generated by
    779     * {@code HashCodeBuilder}.</p>
    780     *
    781     * @param lhs  the left hand {@code double}
    782     * @param rhs  the right hand {@code double}
    783     * @return EqualsBuilder - used to chain calls.
    784     */
    785    public EqualsBuilder append(final double lhs, final double rhs) {
    786        if (!isEquals) {
    787            return this;
    788        }
    789        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    790    }
    791
    792    /**
    793     * <p>Test if two {@code float}s are equal by testing that the
    794     * pattern of bits returned by doubleToLong are equal.</p>
    795     *
    796     * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
    797     *
    798     * <p>It is compatible with the hash code generated by
    799     * {@code HashCodeBuilder}.</p>
    800     *
    801     * @param lhs  the left hand {@code float}
    802     * @param rhs  the right hand {@code float}
    803     * @return EqualsBuilder - used to chain calls.
    804     */
    805    public EqualsBuilder append(final float lhs, final float rhs) {
    806        if (!isEquals) {
    807            return this;
    808        }
    809        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    810    }
    811
    812    /**
    813     * <p>Test if two {@code booleans}s are equal.</p>
    814     *
    815     * @param lhs  the left hand {@code boolean}
    816     * @param rhs  the right hand {@code boolean}
    817     * @return EqualsBuilder - used to chain calls.
    818      */
    819    public EqualsBuilder append(final boolean lhs, final boolean rhs) {
    820        if (!isEquals) {
    821            return this;
    822        }
    823        isEquals = lhs == rhs;
    824        return this;
    825    }
    826
    827    /**
    828     * <p>Performs a deep comparison of two {@code Object} arrays.</p>
    829     *
    830     * <p>This also will be called for the top level of
    831     * multi-dimensional, ragged, and multi-typed arrays.</p>
    832     *
    833     * <p>Note that this method does not compare the type of the arrays; it only
    834     * compares the contents.</p>
    835     *
    836     * @param lhs  the left hand {@code Object[]}
    837     * @param rhs  the right hand {@code Object[]}
    838     * @return EqualsBuilder - used to chain calls.
    839     */
    840    public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
    841        if (!isEquals) {
    842            return this;
    843        }
    844        if (lhs == rhs) {
    845            return this;
    846        }
    847        if (lhs == null || rhs == null) {
    848            this.setEquals(false);
    849            return this;
    850        }
    851        if (lhs.length != rhs.length) {
    852            this.setEquals(false);
    853            return this;
    854        }
    855        for (int i = 0; i < lhs.length && isEquals; ++i) {
    856            append(lhs[i], rhs[i]);
    857        }
    858        return this;
    859    }
    860
    861    /**
    862     * <p>Deep comparison of array of {@code long}. Length and all
    863     * values are compared.</p>
    864     *
    865     * <p>The method {@link #append(long, long)} is used.</p>
    866     *
    867     * @param lhs  the left hand {@code long[]}
    868     * @param rhs  the right hand {@code long[]}
    869     * @return EqualsBuilder - used to chain calls.
    870     */
    871    public EqualsBuilder append(final long[] lhs, final long[] rhs) {
    872        if (!isEquals) {
    873            return this;
    874        }
    875        if (lhs == rhs) {
    876            return this;
    877        }
    878        if (lhs == null || rhs == null) {
    879            this.setEquals(false);
    880            return this;
    881        }
    882        if (lhs.length != rhs.length) {
    883            this.setEquals(false);
    884            return this;
    885        }
    886        for (int i = 0; i < lhs.length && isEquals; ++i) {
    887            append(lhs[i], rhs[i]);
    888        }
    889        return this;
    890    }
    891
    892    /**
    893     * <p>Deep comparison of array of {@code int}. Length and all
    894     * values are compared.</p>
    895     *
    896     * <p>The method {@link #append(int, int)} is used.</p>
    897     *
    898     * @param lhs  the left hand {@code int[]}
    899     * @param rhs  the right hand {@code int[]}
    900     * @return EqualsBuilder - used to chain calls.
    901     */
    902    public EqualsBuilder append(final int[] lhs, final int[] rhs) {
    903        if (!isEquals) {
    904            return this;
    905        }
    906        if (lhs == rhs) {
    907            return this;
    908        }
    909        if (lhs == null || rhs == null) {
    910            this.setEquals(false);
    911            return this;
    912        }
    913        if (lhs.length != rhs.length) {
    914            this.setEquals(false);
    915            return this;
    916        }
    917        for (int i = 0; i < lhs.length && isEquals; ++i) {
    918            append(lhs[i], rhs[i]);
    919        }
    920        return this;
    921    }
    922
    923    /**
    924     * <p>Deep comparison of array of {@code short}. Length and all
    925     * values are compared.</p>
    926     *
    927     * <p>The method {@link #append(short, short)} is used.</p>
    928     *
    929     * @param lhs  the left hand {@code short[]}
    930     * @param rhs  the right hand {@code short[]}
    931     * @return EqualsBuilder - used to chain calls.
    932     */
    933    public EqualsBuilder append(final short[] lhs, final short[] rhs) {
    934        if (!isEquals) {
    935            return this;
    936        }
    937        if (lhs == rhs) {
    938            return this;
    939        }
    940        if (lhs == null || rhs == null) {
    941            this.setEquals(false);
    942            return this;
    943        }
    944        if (lhs.length != rhs.length) {
    945            this.setEquals(false);
    946            return this;
    947        }
    948        for (int i = 0; i < lhs.length && isEquals; ++i) {
    949            append(lhs[i], rhs[i]);
    950        }
    951        return this;
    952    }
    953
    954    /**
    955     * <p>Deep comparison of array of {@code char}. Length and all
    956     * values are compared.</p>
    957     *
    958     * <p>The method {@link #append(char, char)} is used.</p>
    959     *
    960     * @param lhs  the left hand {@code char[]}
    961     * @param rhs  the right hand {@code char[]}
    962     * @return EqualsBuilder - used to chain calls.
    963     */
    964    public EqualsBuilder append(final char[] lhs, final char[] rhs) {
    965        if (!isEquals) {
    966            return this;
    967        }
    968        if (lhs == rhs) {
    969            return this;
    970        }
    971        if (lhs == null || rhs == null) {
    972            this.setEquals(false);
    973            return this;
    974        }
    975        if (lhs.length != rhs.length) {
    976            this.setEquals(false);
    977            return this;
    978        }
    979        for (int i = 0; i < lhs.length && isEquals; ++i) {
    980            append(lhs[i], rhs[i]);
    981        }
    982        return this;
    983    }
    984
    985    /**
    986     * <p>Deep comparison of array of {@code byte}. Length and all
    987     * values are compared.</p>
    988     *
    989     * <p>The method {@link #append(byte, byte)} is used.</p>
    990     *
    991     * @param lhs  the left hand {@code byte[]}
    992     * @param rhs  the right hand {@code byte[]}
    993     * @return EqualsBuilder - used to chain calls.
    994     */
    995    public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
    996        if (!isEquals) {
    997            return this;
    998        }
    999        if (lhs == rhs) {
    1000            return this;
    1001        }
    1002        if (lhs == null || rhs == null) {
    1003            this.setEquals(false);
    1004            return this;
    1005        }
    1006        if (lhs.length != rhs.length) {
    1007            this.setEquals(false);
    1008            return this;
    1009        }
    1010        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1011            append(lhs[i], rhs[i]);
    1012        }
    1013        return this;
    1014    }
    1015
    1016    /**
    1017     * <p>Deep comparison of array of {@code double}. Length and all
    1018     * values are compared.</p>
    1019     *
    1020     * <p>The method {@link #append(double, double)} is used.</p>
    1021     *
    1022     * @param lhs  the left hand {@code double[]}
    1023     * @param rhs  the right hand {@code double[]}
    1024     * @return EqualsBuilder - used to chain calls.
    1025     */
    1026    public EqualsBuilder append(final double[] lhs, final double[] rhs) {
    1027        if (!isEquals) {
    1028            return this;
    1029        }
    1030        if (lhs == rhs) {
    1031            return this;
    1032        }
    1033        if (lhs == null || rhs == null) {
    1034            this.setEquals(false);
    1035            return this;
    1036        }
    1037        if (lhs.length != rhs.length) {
    1038            this.setEquals(false);
    1039            return this;
    1040        }
    1041        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1042            append(lhs[i], rhs[i]);
    1043        }
    1044        return this;
    1045    }
    1046
    1047    /**
    1048     * <p>Deep comparison of array of {@code float}. Length and all
    1049     * values are compared.</p>
    1050     *
    1051     * <p>The method {@link #append(float, float)} is used.</p>
    1052     *
    1053     * @param lhs  the left hand {@code float[]}
    1054     * @param rhs  the right hand {@code float[]}
    1055     * @return EqualsBuilder - used to chain calls.
    1056     */
    1057    public EqualsBuilder append(final float[] lhs, final float[] rhs) {
    1058        if (!isEquals) {
    1059            return this;
    1060        }
    1061        if (lhs == rhs) {
    1062            return this;
    1063        }
    1064        if (lhs == null || rhs == null) {
    1065            this.setEquals(false);
    1066            return this;
    1067        }
    1068        if (lhs.length != rhs.length) {
    1069            this.setEquals(false);
    1070            return this;
    1071        }
    1072        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1073            append(lhs[i], rhs[i]);
    1074        }
    1075        return this;
    1076    }
    1077
    1078    /**
    1079     * <p>Deep comparison of array of {@code boolean}. Length and all
    1080     * values are compared.</p>
    1081     *
    1082     * <p>The method {@link #append(boolean, boolean)} is used.</p>
    1083     *
    1084     * @param lhs  the left hand {@code boolean[]}
    1085     * @param rhs  the right hand {@code boolean[]}
    1086     * @return EqualsBuilder - used to chain calls.
    1087     */
    1088    public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
    1089        if (!isEquals) {
    1090            return this;
    1091        }
    1092        if (lhs == rhs) {
    1093            return this;
    1094        }
    1095        if (lhs == null || rhs == null) {
    1096            this.setEquals(false);
    1097            return this;
    1098        }
    1099        if (lhs.length != rhs.length) {
    1100            this.setEquals(false);
    1101            return this;
    1102        }
    1103        for (int i = 0; i < lhs.length && isEquals; ++i) {
    1104            append(lhs[i], rhs[i]);
    1105        }
    1106        return this;
    1107    }
    1108
    1109    /**
    1110     * <p>Returns {@code true} if the fields that have been checked
    1111     * are all equal.</p>
    1112     *
    1113     * @return boolean
    1114     */
    1115    public boolean isEquals() {
    1116        return this.isEquals;
    1117    }
    1118
    1119    /**
    1120     * <p>Returns {@code true} if the fields that have been checked
    1121     * are all equal.</p>
    1122     *
    1123     * @return {@code true} if all of the fields that have been checked
    1124     *         are equal, {@code false} otherwise.
    1125     *
    1126     * @since 3.0
    1127     */
    1128    @Override
    1129    public Boolean build() {
    1130        return Boolean.valueOf(isEquals());
    1131    }
    1132
    1133    /**
    1134     * Sets the {@code isEquals} value.
    1135     *
    1136     * @param isEquals The value to set.
    1137     * @since 2.1
    1138     */
    1139    protected void setEquals(final boolean isEquals) {
    1140        this.isEquals = isEquals;
    1141    }
    1142
    1143    /**
    1144     * Reset the EqualsBuilder so you can use the same object again
    1145     * @since 2.5
    1146     */
    1147    public void reset() {
    1148        this.isEquals = true;
    1149    }
    1150}