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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.lang3.builder;
18  
19  import java.lang.reflect.AccessibleObject;
20  import java.lang.reflect.Field;
21  import java.lang.reflect.Modifier;
22  import java.util.ArrayList;
23  import java.util.Collection;
24  import java.util.HashSet;
25  import java.util.List;
26  import java.util.Set;
27  
28  import org.apache.commons.lang3.ArrayUtils;
29  import org.apache.commons.lang3.ClassUtils;
30  import org.apache.commons.lang3.tuple.Pair;
31  
32  /**
33   * <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
34   *
35   * <p> This class provides methods to build a good equals method for any
36   * class. It follows rules laid out in
37   * <a href="http://www.oracle.com/technetwork/java/effectivejava-136174.html">Effective Java</a>
38   * , by Joshua Bloch. In particular the rule for comparing <code>doubles</code>,
39   * <code>floats</code>, and arrays can be tricky. Also, making sure that
40   * <code>equals()</code> and <code>hashCode()</code> are consistent can be
41   * difficult.</p>
42   *
43   * <p>Two Objects that compare as equals must generate the same hash code,
44   * but two Objects with the same hash code do not have to be equal.</p>
45   *
46   * <p>All relevant fields should be included in the calculation of equals.
47   * Derived fields may be ignored. In particular, any field used in
48   * generating a hash code must be used in the equals method, and vice
49   * versa.</p>
50   *
51   * <p>Typical use for the code is as follows:</p>
52   * <pre>
53   * public boolean equals(Object obj) {
54   *   if (obj == null) { return false; }
55   *   if (obj == this) { return true; }
56   *   if (obj.getClass() != getClass()) {
57   *     return false;
58   *   }
59   *   MyClass rhs = (MyClass) obj;
60   *   return new EqualsBuilder()
61   *                 .appendSuper(super.equals(obj))
62   *                 .append(field1, rhs.field1)
63   *                 .append(field2, rhs.field2)
64   *                 .append(field3, rhs.field3)
65   *                 .isEquals();
66   *  }
67   * </pre>
68   *
69   * <p> Alternatively, there is a method that uses reflection to determine
70   * the fields to test. Because these fields are usually private, the method,
71   * <code>reflectionEquals</code>, uses <code>AccessibleObject.setAccessible</code> to
72   * change the visibility of the fields. This will fail under a security
73   * manager, unless the appropriate permissions are set up correctly. It is
74   * also slower than testing explicitly.  Non-primitive fields are compared using
75   * <code>equals()</code>.</p>
76   *
77   * <p> A typical invocation for this method would look like:</p>
78   * <pre>
79   * public boolean equals(Object obj) {
80   *   return EqualsBuilder.reflectionEquals(this, obj);
81   * }
82   * </pre>
83   *
84   * <p>The {@link EqualsExclude} annotation can be used to exclude fields from being
85   * used by the <code>reflectionEquals</code> methods.</p>
86   *
87   * @since 1.0
88   */
89  public class EqualsBuilder implements Builder<Boolean> {
90  
91      /**
92       * <p>
93       * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
94       * </p>
95       *
96       * @since 3.0
97       */
98      private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = new ThreadLocal<>();
99  
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</code> 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</code> 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</code> object to lookup in registry
155      * @param rhs the other object to lookup on registry
156      * @return boolean <code>true</code> 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</code> 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</code> 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</code>.
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</code>.</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 include transient fields when reflectively comparing objects.
249      * @param testRecursive  whether to do a recursive test
250      * @return EqualsBuilder - used to chain calls.
251      * @since 3.6
252      */
253     public EqualsBuilder setTestRecursive(final boolean testRecursive) {
254         this.testRecursive = testRecursive;
255         return this;
256     }
257 
258     /**
259      * <p>Set <code>Class</code>es whose instances should be compared by calling their <code>equals</code>
260      * although being in recursive mode. So the fields of theses classes will not be compared recursively by reflection.</p>
261      *
262      * <p>Here you should name classes having non-transient fields which are cache fields being set lazily.<br>
263      * Prominent example being {@link String} class with its hash code cache field. Due to the importance
264      * of the <code>String</code> class, it is included in the default bypasses classes. Usually, if you use
265      * your own set of classes here, remember to include <code>String</code> class, too.</p>
266      * @param bypassReflectionClasses  classes to bypass reflection test
267      * @return EqualsBuilder - used to chain calls.
268      * @since 3.8
269      */
270     public EqualsBuilder setBypassReflectionClasses(List<Class<?>> bypassReflectionClasses) {
271         this.bypassReflectionClasses = bypassReflectionClasses;
272         return this;
273     }
274 
275     /**
276      * Set the superclass to reflect up to at reflective tests.
277      * @param reflectUpToClass the super class to reflect up to
278      * @return EqualsBuilder - used to chain calls.
279      * @since 3.6
280      */
281     public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass) {
282         this.reflectUpToClass = reflectUpToClass;
283         return this;
284     }
285 
286     /**
287      * Set field names to be excluded by reflection tests.
288      * @param excludeFields the fields to exclude
289      * @return EqualsBuilder - used to chain calls.
290      * @since 3.6
291      */
292     public EqualsBuilder setExcludeFields(final String... excludeFields) {
293         this.excludeFields = excludeFields;
294         return this;
295     }
296 
297 
298     /**
299      * <p>This method uses reflection to determine if the two <code>Object</code>s
300      * are equal.</p>
301      *
302      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
303      * fields. This means that it will throw a security exception if run under
304      * a security manager, if the permissions are not set up correctly. It is also
305      * not as efficient as testing explicitly. Non-primitive fields are compared using
306      * <code>equals()</code>.</p>
307      *
308      * <p>Transient members will be not be tested, as they are likely derived
309      * fields, and not part of the value of the Object.</p>
310      *
311      * <p>Static fields will not be tested. Superclass fields will be included.</p>
312      *
313      * @param lhs  <code>this</code> object
314      * @param rhs  the other object
315      * @param excludeFields  Collection of String field names to exclude from testing
316      * @return <code>true</code> if the two Objects have tested equals.
317      *
318      * @see EqualsExclude
319      */
320     public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
321         return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
322     }
323 
324     /**
325      * <p>This method uses reflection to determine if the two <code>Object</code>s
326      * are equal.</p>
327      *
328      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
329      * fields. This means that it will throw a security exception if run under
330      * a security manager, if the permissions are not set up correctly. It is also
331      * not as efficient as testing explicitly. Non-primitive fields are compared using
332      * <code>equals()</code>.</p>
333      *
334      * <p>Transient members will be not be tested, as they are likely derived
335      * fields, and not part of the value of the Object.</p>
336      *
337      * <p>Static fields will not be tested. Superclass fields will be included.</p>
338      *
339      * @param lhs  <code>this</code> object
340      * @param rhs  the other object
341      * @param excludeFields  array of field names to exclude from testing
342      * @return <code>true</code> if the two Objects have tested equals.
343      *
344      * @see EqualsExclude
345      */
346     public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
347         return reflectionEquals(lhs, rhs, false, null, excludeFields);
348     }
349 
350     /**
351      * <p>This method uses reflection to determine if the two <code>Object</code>s
352      * are equal.</p>
353      *
354      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
355      * fields. This means that it will throw a security exception if run under
356      * a security manager, if the permissions are not set up correctly. It is also
357      * not as efficient as testing explicitly. Non-primitive fields are compared using
358      * <code>equals()</code>.</p>
359      *
360      * <p>If the TestTransients parameter is set to <code>true</code>, transient
361      * members will be tested, otherwise they are ignored, as they are likely
362      * derived fields, and not part of the value of the <code>Object</code>.</p>
363      *
364      * <p>Static fields will not be tested. Superclass fields will be included.</p>
365      *
366      * @param lhs  <code>this</code> object
367      * @param rhs  the other object
368      * @param testTransients  whether to include transient fields
369      * @return <code>true</code> if the two Objects have tested equals.
370      *
371      * @see EqualsExclude
372      */
373     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
374         return reflectionEquals(lhs, rhs, testTransients, null);
375     }
376 
377     /**
378      * <p>This method uses reflection to determine if the two <code>Object</code>s
379      * are equal.</p>
380      *
381      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
382      * fields. This means that it will throw a security exception if run under
383      * a security manager, if the permissions are not set up correctly. It is also
384      * not as efficient as testing explicitly. Non-primitive fields are compared using
385      * <code>equals()</code>.</p>
386      *
387      * <p>If the testTransients parameter is set to <code>true</code>, transient
388      * members will be tested, otherwise they are ignored, as they are likely
389      * derived fields, and not part of the value of the <code>Object</code>.</p>
390      *
391      * <p>Static fields will not be included. Superclass fields will be appended
392      * up to and including the specified superclass. A null superclass is treated
393      * as java.lang.Object.</p>
394      *
395      * @param lhs  <code>this</code> object
396      * @param rhs  the other object
397      * @param testTransients  whether to include transient fields
398      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
399      *  may be <code>null</code>
400      * @param excludeFields  array of field names to exclude from testing
401      * @return <code>true</code> if the two Objects have tested equals.
402      *
403      * @see EqualsExclude
404      * @since 2.0
405      */
406     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
407             final String... excludeFields) {
408         return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
409     }
410 
411     /**
412      * <p>This method uses reflection to determine if the two <code>Object</code>s
413      * are equal.</p>
414      *
415      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
416      * fields. This means that it will throw a security exception if run under
417      * a security manager, if the permissions are not set up correctly. It is also
418      * not as efficient as testing explicitly. Non-primitive fields are compared using
419      * <code>equals()</code>.</p>
420      *
421      * <p>If the testTransients parameter is set to <code>true</code>, transient
422      * members will be tested, otherwise they are ignored, as they are likely
423      * derived fields, and not part of the value of the <code>Object</code>.</p>
424      *
425      * <p>Static fields will not be included. Superclass fields will be appended
426      * up to and including the specified superclass. A null superclass is treated
427      * as java.lang.Object.</p>
428      *
429      * <p>If the testRecursive parameter is set to <code>true</code>, non primitive
430      * (and non primitive wrapper) field types will be compared by
431      * <code>EqualsBuilder</code> recursively instead of invoking their
432      * <code>equals()</code> method. Leading to a deep reflection equals test.
433      *
434      * @param lhs  <code>this</code> object
435      * @param rhs  the other object
436      * @param testTransients  whether to include transient fields
437      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
438      *  may be <code>null</code>
439      * @param testRecursive  whether to call reflection equals on non primitive
440      *  fields recursively.
441      * @param excludeFields  array of field names to exclude from testing
442      * @return <code>true</code> if the two Objects have tested equals.
443      *
444      * @see EqualsExclude
445      * @since 3.6
446      */
447     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
448             final boolean testRecursive, final String... excludeFields) {
449         if (lhs == rhs) {
450             return true;
451         }
452         if (lhs == null || rhs == null) {
453             return false;
454         }
455         return new EqualsBuilder()
456                     .setExcludeFields(excludeFields)
457                     .setReflectUpToClass(reflectUpToClass)
458                     .setTestTransients(testTransients)
459                     .setTestRecursive(testRecursive)
460                     .reflectionAppend(lhs, rhs)
461                     .isEquals();
462     }
463 
464     /**
465      * <p>Tests if two <code>objects</code> by using reflection.</p>
466      *
467      * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
468      * fields. This means that it will throw a security exception if run under
469      * a security manager, if the permissions are not set up correctly. It is also
470      * not as efficient as testing explicitly. Non-primitive fields are compared using
471      * <code>equals()</code>.</p>
472      *
473      * <p>If the testTransients field is set to <code>true</code>, transient
474      * members will be tested, otherwise they are ignored, as they are likely
475      * derived fields, and not part of the value of the <code>Object</code>.</p>
476      *
477      * <p>Static fields will not be included. Superclass fields will be appended
478      * up to and including the specified superclass in field <code>reflectUpToClass</code>.
479      * A null superclass is treated as java.lang.Object.</p>
480      *
481      * <p>Field names listed in field <code>excludeFields</code> will be ignored.</p>
482      *
483      * <p>If either class of the compared objects is contained in
484      * <code>bypassReflectionClasses</code>, both objects are compared by calling
485      * the equals method of the left hand object with the right hand object as an argument.</p>
486      *
487      * @param lhs  the left hand object
488      * @param rhs  the left hand object
489      * @return EqualsBuilder - used to chain calls.
490      */
491     public EqualsBuilder reflectionAppend(final Object lhs, final Object rhs) {
492         if (!isEquals) {
493             return this;
494         }
495         if (lhs == rhs) {
496             return this;
497         }
498         if (lhs == null || rhs == null) {
499             isEquals = false;
500             return this;
501         }
502 
503         // Find the leaf class since there may be transients in the leaf
504         // class or in classes between the leaf and root.
505         // If we are not testing transients or a subclass has no ivars,
506         // then a subclass can test equals to a superclass.
507         final Class<?> lhsClass = lhs.getClass();
508         final Class<?> rhsClass = rhs.getClass();
509         Class<?> testClass;
510         if (lhsClass.isInstance(rhs)) {
511             testClass = lhsClass;
512             if (!rhsClass.isInstance(lhs)) {
513                 // rhsClass is a subclass of lhsClass
514                 testClass = rhsClass;
515             }
516         } else if (rhsClass.isInstance(lhs)) {
517             testClass = rhsClass;
518             if (!lhsClass.isInstance(rhs)) {
519                 // lhsClass is a subclass of rhsClass
520                 testClass = lhsClass;
521             }
522         } else {
523             // The two classes are not related.
524             isEquals = false;
525             return this;
526         }
527 
528         try {
529             if (testClass.isArray()) {
530                 append(lhs, rhs);
531             } else {
532                 //If either class is being excluded, call normal object equals method on lhsClass.
533                 if (bypassReflectionClasses != null
534                         && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))) {
535                     isEquals = lhs.equals(rhs);
536                 } else {
537                     reflectionAppend(lhs, rhs, testClass);
538                     while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
539                         testClass = testClass.getSuperclass();
540                         reflectionAppend(lhs, rhs, testClass);
541                     }
542                 }
543             }
544         } catch (final IllegalArgumentException e) {
545             // In this case, we tried to test a subclass vs. a superclass and
546             // the subclass has ivars or the ivars are transient and
547             // we are testing transients.
548             // If a subclass has ivars that we are trying to test them, we get an
549             // exception and we know that the objects are not equal.
550             isEquals = false;
551             return this;
552         }
553         return this;
554     }
555 
556     /**
557      * <p>Appends the fields and values defined by the given object of the
558      * given Class.</p>
559      *
560      * @param lhs  the left hand object
561      * @param rhs  the right hand object
562      * @param clazz  the class to append details of
563      */
564     private void reflectionAppend(
565         final Object lhs,
566         final Object rhs,
567         final Class<?> clazz) {
568 
569         if (isRegistered(lhs, rhs)) {
570             return;
571         }
572 
573         try {
574             register(lhs, rhs);
575             final Field[] fields = clazz.getDeclaredFields();
576             AccessibleObject.setAccessible(fields, true);
577             for (int i = 0; i < fields.length && isEquals; i++) {
578                 final Field f = fields[i];
579                 if (!ArrayUtils.contains(excludeFields, f.getName())
580                     && !f.getName().contains("$")
581                     && (testTransients || !Modifier.isTransient(f.getModifiers()))
582                     && !Modifier.isStatic(f.getModifiers())
583                     && !f.isAnnotationPresent(EqualsExclude.class)) {
584                     try {
585                         append(f.get(lhs), f.get(rhs));
586                     } catch (final IllegalAccessException e) {
587                         //this can't happen. Would get a Security exception instead
588                         //throw a runtime exception in case the impossible happens.
589                         throw new InternalError("Unexpected IllegalAccessException");
590                     }
591                 }
592             }
593         } finally {
594             unregister(lhs, rhs);
595         }
596     }
597 
598     //-------------------------------------------------------------------------
599 
600     /**
601      * <p>Adds the result of <code>super.equals()</code> to this builder.</p>
602      *
603      * @param superEquals  the result of calling <code>super.equals()</code>
604      * @return EqualsBuilder - used to chain calls.
605      * @since 2.0
606      */
607     public EqualsBuilder appendSuper(final boolean superEquals) {
608         if (!isEquals) {
609             return this;
610         }
611         isEquals = superEquals;
612         return this;
613     }
614 
615     //-------------------------------------------------------------------------
616 
617     /**
618      * <p>Test if two <code>Object</code>s are equal using either
619      * #{@link #reflectionAppend(Object, Object)}, if object are non
620      * primitives (or wrapper of primitives) or if field <code>testRecursive</code>
621      * is set to <code>false</code>. Otherwise, using their
622      * <code>equals</code> method.</p>
623      *
624      * @param lhs  the left hand object
625      * @param rhs  the right hand object
626      * @return EqualsBuilder - used to chain calls.
627      */
628     public EqualsBuilder append(final Object lhs, final Object rhs) {
629         if (!isEquals) {
630             return this;
631         }
632         if (lhs == rhs) {
633             return this;
634         }
635         if (lhs == null || rhs == null) {
636             this.setEquals(false);
637             return this;
638         }
639         final Class<?> lhsClass = lhs.getClass();
640         if (lhsClass.isArray()) {
641             // factor out array case in order to keep method small enough
642             // to be inlined
643             appendArray(lhs, rhs);
644         } else {
645             // 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         }
652         return this;
653     }
654 
655     /**
656      * <p>Test if an <code>Object</code> is equal to an array.</p>
657      *
658      * @param lhs  the left hand object, an array
659      * @param rhs  the right hand object
660      */
661     private void appendArray(final Object lhs, final Object rhs) {
662         // First we compare different dimensions, for example: a boolean[][] to a boolean[]
663         // then we 'Switch' on type of array, to dispatch to the correct handler
664         // This handles multi dimensional arrays of the same depth
665         if (lhs.getClass() != rhs.getClass()) {
666             this.setEquals(false);
667         } else if (lhs instanceof long[]) {
668             append((long[]) lhs, (long[]) rhs);
669         } else if (lhs instanceof int[]) {
670             append((int[]) lhs, (int[]) rhs);
671         } else if (lhs instanceof short[]) {
672             append((short[]) lhs, (short[]) rhs);
673         } else if (lhs instanceof char[]) {
674             append((char[]) lhs, (char[]) rhs);
675         } else if (lhs instanceof byte[]) {
676             append((byte[]) lhs, (byte[]) rhs);
677         } else if (lhs instanceof double[]) {
678             append((double[]) lhs, (double[]) rhs);
679         } else if (lhs instanceof float[]) {
680             append((float[]) lhs, (float[]) rhs);
681         } else if (lhs instanceof boolean[]) {
682             append((boolean[]) lhs, (boolean[]) rhs);
683         } else {
684             // Not an array of primitives
685             append((Object[]) lhs, (Object[]) rhs);
686         }
687     }
688 
689     /**
690      * <p>
691      * Test if two <code>long</code> s are equal.
692      * </p>
693      *
694      * @param lhs
695      *                  the left hand <code>long</code>
696      * @param rhs
697      *                  the right hand <code>long</code>
698      * @return EqualsBuilder - used to chain calls.
699      */
700     public EqualsBuilder append(final long lhs, final long rhs) {
701         if (!isEquals) {
702             return this;
703         }
704         isEquals = lhs == rhs;
705         return this;
706     }
707 
708     /**
709      * <p>Test if two <code>int</code>s are equal.</p>
710      *
711      * @param lhs  the left hand <code>int</code>
712      * @param rhs  the right hand <code>int</code>
713      * @return EqualsBuilder - used to chain calls.
714      */
715     public EqualsBuilder append(final int lhs, final int rhs) {
716         if (!isEquals) {
717             return this;
718         }
719         isEquals = lhs == rhs;
720         return this;
721     }
722 
723     /**
724      * <p>Test if two <code>short</code>s are equal.</p>
725      *
726      * @param lhs  the left hand <code>short</code>
727      * @param rhs  the right hand <code>short</code>
728      * @return EqualsBuilder - used to chain calls.
729      */
730     public EqualsBuilder append(final short lhs, final short rhs) {
731         if (!isEquals) {
732             return this;
733         }
734         isEquals = lhs == rhs;
735         return this;
736     }
737 
738     /**
739      * <p>Test if two <code>char</code>s are equal.</p>
740      *
741      * @param lhs  the left hand <code>char</code>
742      * @param rhs  the right hand <code>char</code>
743      * @return EqualsBuilder - used to chain calls.
744      */
745     public EqualsBuilder append(final char lhs, final char rhs) {
746         if (!isEquals) {
747             return this;
748         }
749         isEquals = lhs == rhs;
750         return this;
751     }
752 
753     /**
754      * <p>Test if two <code>byte</code>s are equal.</p>
755      *
756      * @param lhs  the left hand <code>byte</code>
757      * @param rhs  the right hand <code>byte</code>
758      * @return EqualsBuilder - used to chain calls.
759      */
760     public EqualsBuilder append(final byte lhs, final byte rhs) {
761         if (!isEquals) {
762             return this;
763         }
764         isEquals = lhs == rhs;
765         return this;
766     }
767 
768     /**
769      * <p>Test if two <code>double</code>s are equal by testing that the
770      * pattern of bits returned by <code>doubleToLong</code> are equal.</p>
771      *
772      * <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
773      *
774      * <p>It is compatible with the hash code generated by
775      * <code>HashCodeBuilder</code>.</p>
776      *
777      * @param lhs  the left hand <code>double</code>
778      * @param rhs  the right hand <code>double</code>
779      * @return EqualsBuilder - used to chain calls.
780      */
781     public EqualsBuilder append(final double lhs, final double rhs) {
782         if (!isEquals) {
783             return this;
784         }
785         return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
786     }
787 
788     /**
789      * <p>Test if two <code>float</code>s are equal byt testing that the
790      * pattern of bits returned by doubleToLong are equal.</p>
791      *
792      * <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
793      *
794      * <p>It is compatible with the hash code generated by
795      * <code>HashCodeBuilder</code>.</p>
796      *
797      * @param lhs  the left hand <code>float</code>
798      * @param rhs  the right hand <code>float</code>
799      * @return EqualsBuilder - used to chain calls.
800      */
801     public EqualsBuilder append(final float lhs, final float rhs) {
802         if (!isEquals) {
803             return this;
804         }
805         return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
806     }
807 
808     /**
809      * <p>Test if two <code>booleans</code>s are equal.</p>
810      *
811      * @param lhs  the left hand <code>boolean</code>
812      * @param rhs  the right hand <code>boolean</code>
813      * @return EqualsBuilder - used to chain calls.
814       */
815     public EqualsBuilder append(final boolean lhs, final boolean rhs) {
816         if (!isEquals) {
817             return this;
818         }
819         isEquals = lhs == rhs;
820         return this;
821     }
822 
823     /**
824      * <p>Performs a deep comparison of two <code>Object</code> arrays.</p>
825      *
826      * <p>This also will be called for the top level of
827      * multi-dimensional, ragged, and multi-typed arrays.</p>
828      *
829      * <p>Note that this method does not compare the type of the arrays; it only
830      * compares the contents.</p>
831      *
832      * @param lhs  the left hand <code>Object[]</code>
833      * @param rhs  the right hand <code>Object[]</code>
834      * @return EqualsBuilder - used to chain calls.
835      */
836     public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
837         if (!isEquals) {
838             return this;
839         }
840         if (lhs == rhs) {
841             return this;
842         }
843         if (lhs == null || rhs == null) {
844             this.setEquals(false);
845             return this;
846         }
847         if (lhs.length != rhs.length) {
848             this.setEquals(false);
849             return this;
850         }
851         for (int i = 0; i < lhs.length && isEquals; ++i) {
852             append(lhs[i], rhs[i]);
853         }
854         return this;
855     }
856 
857     /**
858      * <p>Deep comparison of array of <code>long</code>. Length and all
859      * values are compared.</p>
860      *
861      * <p>The method {@link #append(long, long)} is used.</p>
862      *
863      * @param lhs  the left hand <code>long[]</code>
864      * @param rhs  the right hand <code>long[]</code>
865      * @return EqualsBuilder - used to chain calls.
866      */
867     public EqualsBuilder append(final long[] lhs, final long[] rhs) {
868         if (!isEquals) {
869             return this;
870         }
871         if (lhs == rhs) {
872             return this;
873         }
874         if (lhs == null || rhs == null) {
875             this.setEquals(false);
876             return this;
877         }
878         if (lhs.length != rhs.length) {
879             this.setEquals(false);
880             return this;
881         }
882         for (int i = 0; i < lhs.length && isEquals; ++i) {
883             append(lhs[i], rhs[i]);
884         }
885         return this;
886     }
887 
888     /**
889      * <p>Deep comparison of array of <code>int</code>. Length and all
890      * values are compared.</p>
891      *
892      * <p>The method {@link #append(int, int)} is used.</p>
893      *
894      * @param lhs  the left hand <code>int[]</code>
895      * @param rhs  the right hand <code>int[]</code>
896      * @return EqualsBuilder - used to chain calls.
897      */
898     public EqualsBuilder append(final int[] lhs, final int[] rhs) {
899         if (!isEquals) {
900             return this;
901         }
902         if (lhs == rhs) {
903             return this;
904         }
905         if (lhs == null || rhs == null) {
906             this.setEquals(false);
907             return this;
908         }
909         if (lhs.length != rhs.length) {
910             this.setEquals(false);
911             return this;
912         }
913         for (int i = 0; i < lhs.length && isEquals; ++i) {
914             append(lhs[i], rhs[i]);
915         }
916         return this;
917     }
918 
919     /**
920      * <p>Deep comparison of array of <code>short</code>. Length and all
921      * values are compared.</p>
922      *
923      * <p>The method {@link #append(short, short)} is used.</p>
924      *
925      * @param lhs  the left hand <code>short[]</code>
926      * @param rhs  the right hand <code>short[]</code>
927      * @return EqualsBuilder - used to chain calls.
928      */
929     public EqualsBuilder append(final short[] lhs, final short[] rhs) {
930         if (!isEquals) {
931             return this;
932         }
933         if (lhs == rhs) {
934             return this;
935         }
936         if (lhs == null || rhs == null) {
937             this.setEquals(false);
938             return this;
939         }
940         if (lhs.length != rhs.length) {
941             this.setEquals(false);
942             return this;
943         }
944         for (int i = 0; i < lhs.length && isEquals; ++i) {
945             append(lhs[i], rhs[i]);
946         }
947         return this;
948     }
949 
950     /**
951      * <p>Deep comparison of array of <code>char</code>. Length and all
952      * values are compared.</p>
953      *
954      * <p>The method {@link #append(char, char)} is used.</p>
955      *
956      * @param lhs  the left hand <code>char[]</code>
957      * @param rhs  the right hand <code>char[]</code>
958      * @return EqualsBuilder - used to chain calls.
959      */
960     public EqualsBuilder append(final char[] lhs, final char[] rhs) {
961         if (!isEquals) {
962             return this;
963         }
964         if (lhs == rhs) {
965             return this;
966         }
967         if (lhs == null || rhs == null) {
968             this.setEquals(false);
969             return this;
970         }
971         if (lhs.length != rhs.length) {
972             this.setEquals(false);
973             return this;
974         }
975         for (int i = 0; i < lhs.length && isEquals; ++i) {
976             append(lhs[i], rhs[i]);
977         }
978         return this;
979     }
980 
981     /**
982      * <p>Deep comparison of array of <code>byte</code>. Length and all
983      * values are compared.</p>
984      *
985      * <p>The method {@link #append(byte, byte)} is used.</p>
986      *
987      * @param lhs  the left hand <code>byte[]</code>
988      * @param rhs  the right hand <code>byte[]</code>
989      * @return EqualsBuilder - used to chain calls.
990      */
991     public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
992         if (!isEquals) {
993             return this;
994         }
995         if (lhs == rhs) {
996             return this;
997         }
998         if (lhs == null || rhs == null) {
999             this.setEquals(false);
1000             return this;
1001         }
1002         if (lhs.length != rhs.length) {
1003             this.setEquals(false);
1004             return this;
1005         }
1006         for (int i = 0; i < lhs.length && isEquals; ++i) {
1007             append(lhs[i], rhs[i]);
1008         }
1009         return this;
1010     }
1011 
1012     /**
1013      * <p>Deep comparison of array of <code>double</code>. Length and all
1014      * values are compared.</p>
1015      *
1016      * <p>The method {@link #append(double, double)} is used.</p>
1017      *
1018      * @param lhs  the left hand <code>double[]</code>
1019      * @param rhs  the right hand <code>double[]</code>
1020      * @return EqualsBuilder - used to chain calls.
1021      */
1022     public EqualsBuilder append(final double[] lhs, final double[] rhs) {
1023         if (!isEquals) {
1024             return this;
1025         }
1026         if (lhs == rhs) {
1027             return this;
1028         }
1029         if (lhs == null || rhs == null) {
1030             this.setEquals(false);
1031             return this;
1032         }
1033         if (lhs.length != rhs.length) {
1034             this.setEquals(false);
1035             return this;
1036         }
1037         for (int i = 0; i < lhs.length && isEquals; ++i) {
1038             append(lhs[i], rhs[i]);
1039         }
1040         return this;
1041     }
1042 
1043     /**
1044      * <p>Deep comparison of array of <code>float</code>. Length and all
1045      * values are compared.</p>
1046      *
1047      * <p>The method {@link #append(float, float)} is used.</p>
1048      *
1049      * @param lhs  the left hand <code>float[]</code>
1050      * @param rhs  the right hand <code>float[]</code>
1051      * @return EqualsBuilder - used to chain calls.
1052      */
1053     public EqualsBuilder append(final float[] lhs, final float[] rhs) {
1054         if (!isEquals) {
1055             return this;
1056         }
1057         if (lhs == rhs) {
1058             return this;
1059         }
1060         if (lhs == null || rhs == null) {
1061             this.setEquals(false);
1062             return this;
1063         }
1064         if (lhs.length != rhs.length) {
1065             this.setEquals(false);
1066             return this;
1067         }
1068         for (int i = 0; i < lhs.length && isEquals; ++i) {
1069             append(lhs[i], rhs[i]);
1070         }
1071         return this;
1072     }
1073 
1074     /**
1075      * <p>Deep comparison of array of <code>boolean</code>. Length and all
1076      * values are compared.</p>
1077      *
1078      * <p>The method {@link #append(boolean, boolean)} is used.</p>
1079      *
1080      * @param lhs  the left hand <code>boolean[]</code>
1081      * @param rhs  the right hand <code>boolean[]</code>
1082      * @return EqualsBuilder - used to chain calls.
1083      */
1084     public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
1085         if (!isEquals) {
1086             return this;
1087         }
1088         if (lhs == rhs) {
1089             return this;
1090         }
1091         if (lhs == null || rhs == null) {
1092             this.setEquals(false);
1093             return this;
1094         }
1095         if (lhs.length != rhs.length) {
1096             this.setEquals(false);
1097             return this;
1098         }
1099         for (int i = 0; i < lhs.length && isEquals; ++i) {
1100             append(lhs[i], rhs[i]);
1101         }
1102         return this;
1103     }
1104 
1105     /**
1106      * <p>Returns <code>true</code> if the fields that have been checked
1107      * are all equal.</p>
1108      *
1109      * @return boolean
1110      */
1111     public boolean isEquals() {
1112         return this.isEquals;
1113     }
1114 
1115     /**
1116      * <p>Returns <code>true</code> if the fields that have been checked
1117      * are all equal.</p>
1118      *
1119      * @return <code>true</code> if all of the fields that have been checked
1120      *         are equal, <code>false</code> otherwise.
1121      *
1122      * @since 3.0
1123      */
1124     @Override
1125     public Boolean build() {
1126         return Boolean.valueOf(isEquals());
1127     }
1128 
1129     /**
1130      * Sets the <code>isEquals</code> value.
1131      *
1132      * @param isEquals The value to set.
1133      * @since 2.1
1134      */
1135     protected void setEquals(final boolean isEquals) {
1136         this.isEquals = isEquals;
1137     }
1138 
1139     /**
1140      * Reset the EqualsBuilder so you can use the same object again
1141      * @since 2.5
1142      */
1143     public void reset() {
1144         this.isEquals = true;
1145     }
1146 }