View Javadoc
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   * Assists in implementing {@link Object#equals(Object)} methods.
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="https://www.oracle.com/java/technologies/effectivejava.html">Effective Java</a>
38   * , by Joshua Bloch. In particular the rule for comparing {@code doubles},
39   * {@code floats}, and arrays can be tricky. Also, making sure that
40   * {@code equals()} and {@code hashCode()} 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}, uses {@code AccessibleObject.setAccessible} 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()}.</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} methods.</p>
86   *
87   * @since 1.0
88   */
89  public class EqualsBuilder implements Builder<Boolean> {
90  
91      /**
92       * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
93       *
94       * @since 3.0
95       */
96      private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = ThreadLocal.withInitial(HashSet::new);
97  
98      /*
99       * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
100      * we are in the process of calculating.
101      *
102      * So we generate a one-to-one mapping from the original object to a new object.
103      *
104      * Now HashSet uses equals() to determine if two elements with the same hash code really
105      * are equal, so we also need to ensure that the replacement objects are only equal
106      * if the original objects are identical.
107      *
108      * The original implementation (2.4 and before) used the System.identityHashCode()
109      * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
110      *
111      * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
112      * to disambiguate the duplicate ids.
113      */
114 
115     /**
116      * Converters value pair into a register pair.
117      *
118      * @param lhs {@code this} object
119      * @param rhs the other object
120      *
121      * @return the pair
122      */
123     static Pair<IDKey, IDKey> getRegisterPair(final Object lhs, final Object rhs) {
124         return Pair.of(new IDKey(lhs), new IDKey(rhs));
125     }
126 
127     /**
128      * Returns the registry of object pairs being traversed by the reflection
129      * methods in the current thread.
130      *
131      * @return Set the registry of objects being traversed
132      * @since 3.0
133      */
134     static Set<Pair<IDKey, IDKey>> getRegistry() {
135         return REGISTRY.get();
136     }
137 
138     /**
139      * Returns {@code true} if the registry contains the given object pair.
140      * Used by the reflection methods to avoid infinite loops.
141      * Objects might be swapped therefore a check is needed if the object pair
142      * is registered in given or swapped order.
143      *
144      * @param lhs {@code this} object to lookup in registry
145      * @param rhs the other object to lookup on registry
146      * @return boolean {@code true} if the registry contains the given object.
147      * @since 3.0
148      */
149     static boolean isRegistered(final Object lhs, final Object rhs) {
150         final Set<Pair<IDKey, IDKey>> registry = getRegistry();
151         final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
152         final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getRight(), pair.getLeft());
153         return registry != null && (registry.contains(pair) || registry.contains(swappedPair));
154     }
155 
156     /**
157      * This method uses reflection to determine if the two {@link Object}s
158      * are equal.
159      *
160      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
161      * fields. This means that it will throw a security exception if run under
162      * a security manager, if the permissions are not set up correctly. It is also
163      * not as efficient as testing explicitly. Non-primitive fields are compared using
164      * {@code equals()}.</p>
165      *
166      * <p>If the TestTransients parameter is set to {@code true}, transient
167      * members will be tested, otherwise they are ignored, as they are likely
168      * derived fields, and not part of the value of the {@link Object}.</p>
169      *
170      * <p>Static fields will not be tested. Superclass fields will be included.</p>
171      *
172      * @param lhs  {@code this} object
173      * @param rhs  the other object
174      * @param testTransients  whether to include transient fields
175      * @return {@code true} if the two Objects have tested equals.
176      *
177      * @see EqualsExclude
178      */
179     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
180         return reflectionEquals(lhs, rhs, testTransients, null);
181     }
182 
183     /**
184      * This method uses reflection to determine if the two {@link Object}s
185      * are equal.
186      *
187      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
188      * fields. This means that it will throw a security exception if run under
189      * a security manager, if the permissions are not set up correctly. It is also
190      * not as efficient as testing explicitly. Non-primitive fields are compared using
191      * {@code equals()}.</p>
192      *
193      * <p>If the testTransients parameter is set to {@code true}, transient
194      * members will be tested, otherwise they are ignored, as they are likely
195      * derived fields, and not part of the value of the {@link Object}.</p>
196      *
197      * <p>Static fields will not be included. Superclass fields will be appended
198      * up to and including the specified superclass. A null superclass is treated
199      * as java.lang.Object.</p>
200      *
201      * <p>If the testRecursive parameter is set to {@code true}, non primitive
202      * (and non primitive wrapper) field types will be compared by
203      * {@link EqualsBuilder} recursively instead of invoking their
204      * {@code equals()} method. Leading to a deep reflection equals test.
205      *
206      * @param lhs  {@code this} object
207      * @param rhs  the other object
208      * @param testTransients  whether to include transient fields
209      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
210      *  may be {@code null}
211      * @param testRecursive  whether to call reflection equals on non-primitive
212      *  fields recursively.
213      * @param excludeFields  array of field names to exclude from testing
214      * @return {@code true} if the two Objects have tested equals.
215      *
216      * @see EqualsExclude
217      * @since 3.6
218      */
219     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
220             final boolean testRecursive, final String... excludeFields) {
221         if (lhs == rhs) {
222             return true;
223         }
224         if (lhs == null || rhs == null) {
225             return false;
226         }
227         // @formatter:off
228         return new EqualsBuilder()
229             .setExcludeFields(excludeFields)
230             .setReflectUpToClass(reflectUpToClass)
231             .setTestTransients(testTransients)
232             .setTestRecursive(testRecursive)
233             .reflectionAppend(lhs, rhs)
234             .isEquals();
235         // @formatter:on
236     }
237 
238     /**
239      * This method uses reflection to determine if the two {@link Object}s
240      * are equal.
241      *
242      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
243      * fields. This means that it will throw a security exception if run under
244      * a security manager, if the permissions are not set up correctly. It is also
245      * not as efficient as testing explicitly. Non-primitive fields are compared using
246      * {@code equals()}.</p>
247      *
248      * <p>If the testTransients parameter is set to {@code true}, transient
249      * members will be tested, otherwise they are ignored, as they are likely
250      * derived fields, and not part of the value of the {@link Object}.</p>
251      *
252      * <p>Static fields will not be included. Superclass fields will be appended
253      * up to and including the specified superclass. A null superclass is treated
254      * as java.lang.Object.</p>
255      *
256      * @param lhs  {@code this} object
257      * @param rhs  the other object
258      * @param testTransients  whether to include transient fields
259      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
260      *  may be {@code null}
261      * @param excludeFields  array of field names to exclude from testing
262      * @return {@code true} if the two Objects have tested equals.
263      *
264      * @see EqualsExclude
265      * @since 2.0
266      */
267     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
268             final String... excludeFields) {
269         return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
270     }
271 
272     /**
273      * This method uses reflection to determine if the two {@link Object}s
274      * are equal.
275      *
276      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
277      * fields. This means that it will throw a security exception if run under
278      * a security manager, if the permissions are not set up correctly. It is also
279      * not as efficient as testing explicitly. Non-primitive fields are compared using
280      * {@code equals()}.</p>
281      *
282      * <p>Transient members will be not be tested, as they are likely derived
283      * fields, and not part of the value of the Object.</p>
284      *
285      * <p>Static fields will not be tested. Superclass fields will be included.</p>
286      *
287      * @param lhs  {@code this} object
288      * @param rhs  the other object
289      * @param excludeFields  Collection of String field names to exclude from testing
290      * @return {@code true} if the two Objects have tested equals.
291      *
292      * @see EqualsExclude
293      */
294     public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
295         return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
296     }
297 
298     /**
299      * This method uses reflection to determine if the two {@link Object}s
300      * are equal.
301      *
302      * <p>It uses {@code AccessibleObject.setAccessible} 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()}.</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} object
314      * @param rhs  the other object
315      * @param excludeFields  array of field names to exclude from testing
316      * @return {@code true} if the two Objects have tested equals.
317      *
318      * @see EqualsExclude
319      */
320     public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
321         return reflectionEquals(lhs, rhs, false, null, excludeFields);
322     }
323 
324     /**
325      * Registers the given object pair.
326      * Used by the reflection methods to avoid infinite loops.
327      *
328      * @param lhs {@code this} object to register
329      * @param rhs the other object to register
330      */
331     private static void register(final Object lhs, final Object rhs) {
332         getRegistry().add(getRegisterPair(lhs, rhs));
333     }
334 
335     /**
336      * Unregisters the given object pair.
337      *
338      * <p>
339      * Used by the reflection methods to avoid infinite loops.
340      * </p>
341      *
342      * @param lhs {@code this} object to unregister
343      * @param rhs the other object to unregister
344      * @since 3.0
345      */
346     private static void unregister(final Object lhs, final Object rhs) {
347         final Set<Pair<IDKey, IDKey>> registry = getRegistry();
348         registry.remove(getRegisterPair(lhs, rhs));
349         if (registry.isEmpty()) {
350             REGISTRY.remove();
351         }
352     }
353 
354     /**
355      * If the fields tested are equals.
356      * The default value is {@code true}.
357      */
358     private boolean isEquals = true;
359 
360     private boolean testTransients;
361 
362     private boolean testRecursive;
363 
364     private List<Class<?>> bypassReflectionClasses;
365 
366     private Class<?> reflectUpToClass;
367 
368     private String[] excludeFields;
369 
370     /**
371      * Constructor for EqualsBuilder.
372      *
373      * <p>Starts off assuming that equals is {@code true}.</p>
374      * @see Object#equals(Object)
375      */
376     public EqualsBuilder() {
377         // set up default classes to bypass reflection for
378         bypassReflectionClasses = new ArrayList<>(1);
379         bypassReflectionClasses.add(String.class); //hashCode field being lazy but not transient
380     }
381 
382     /**
383      * Test if two {@code booleans}s are equal.
384      *
385      * @param lhs  the left-hand side {@code boolean}
386      * @param rhs  the right-hand side {@code boolean}
387      * @return {@code this} instance.
388       */
389     public EqualsBuilder append(final boolean lhs, final boolean rhs) {
390         if (!isEquals) {
391             return this;
392         }
393         isEquals = lhs == rhs;
394         return this;
395     }
396 
397     /**
398      * Deep comparison of array of {@code boolean}. Length and all
399      * values are compared.
400      *
401      * <p>The method {@link #append(boolean, boolean)} is used.</p>
402      *
403      * @param lhs  the left-hand side {@code boolean[]}
404      * @param rhs  the right-hand side {@code boolean[]}
405      * @return {@code this} instance.
406      */
407     public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
408         if (!isEquals) {
409             return this;
410         }
411         if (lhs == rhs) {
412             return this;
413         }
414         if (lhs == null || rhs == null) {
415             this.setEquals(false);
416             return this;
417         }
418         if (lhs.length != rhs.length) {
419             this.setEquals(false);
420             return this;
421         }
422         for (int i = 0; i < lhs.length && isEquals; ++i) {
423             append(lhs[i], rhs[i]);
424         }
425         return this;
426     }
427 
428     /**
429      * Test if two {@code byte}s are equal.
430      *
431      * @param lhs  the left-hand side {@code byte}
432      * @param rhs  the right-hand side {@code byte}
433      * @return {@code this} instance.
434      */
435     public EqualsBuilder append(final byte lhs, final byte rhs) {
436         if (isEquals) {
437             isEquals = lhs == rhs;
438         }
439         return this;
440     }
441 
442     /**
443      * Deep comparison of array of {@code byte}. Length and all
444      * values are compared.
445      *
446      * <p>The method {@link #append(byte, byte)} is used.</p>
447      *
448      * @param lhs  the left-hand side {@code byte[]}
449      * @param rhs  the right-hand side {@code byte[]}
450      * @return {@code this} instance.
451      */
452     public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
453         if (!isEquals) {
454             return this;
455         }
456         if (lhs == rhs) {
457             return this;
458         }
459         if (lhs == null || rhs == null) {
460             setEquals(false);
461             return this;
462         }
463         if (lhs.length != rhs.length) {
464             setEquals(false);
465             return this;
466         }
467         for (int i = 0; i < lhs.length && isEquals; ++i) {
468             append(lhs[i], rhs[i]);
469         }
470         return this;
471     }
472 
473     /**
474      * Test if two {@code char}s are equal.
475      *
476      * @param lhs  the left-hand side {@code char}
477      * @param rhs  the right-hand side {@code char}
478      * @return {@code this} instance.
479      */
480     public EqualsBuilder append(final char lhs, final char rhs) {
481         if (isEquals) {
482             isEquals = lhs == rhs;
483         }
484         return this;
485     }
486 
487     /**
488      * Deep comparison of array of {@code char}. Length and all
489      * values are compared.
490      *
491      * <p>The method {@link #append(char, char)} is used.</p>
492      *
493      * @param lhs  the left-hand side {@code char[]}
494      * @param rhs  the right-hand side {@code char[]}
495      * @return {@code this} instance.
496      */
497     public EqualsBuilder append(final char[] lhs, final char[] rhs) {
498         if (!isEquals) {
499             return this;
500         }
501         if (lhs == rhs) {
502             return this;
503         }
504         if (lhs == null || rhs == null) {
505             setEquals(false);
506             return this;
507         }
508         if (lhs.length != rhs.length) {
509             setEquals(false);
510             return this;
511         }
512         for (int i = 0; i < lhs.length && isEquals; ++i) {
513             append(lhs[i], rhs[i]);
514         }
515         return this;
516     }
517 
518     /**
519      * Test if two {@code double}s are equal by testing that the
520      * pattern of bits returned by {@code doubleToLong} are equal.
521      *
522      * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
523      *
524      * <p>It is compatible with the hash code generated by
525      * {@link HashCodeBuilder}.</p>
526      *
527      * @param lhs  the left-hand side {@code double}
528      * @param rhs  the right-hand side {@code double}
529      * @return {@code this} instance.
530      */
531     public EqualsBuilder append(final double lhs, final double rhs) {
532         if (isEquals) {
533             return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
534         }
535         return this;
536     }
537 
538     /**
539      * Deep comparison of array of {@code double}. Length and all
540      * values are compared.
541      *
542      * <p>The method {@link #append(double, double)} is used.</p>
543      *
544      * @param lhs  the left-hand side {@code double[]}
545      * @param rhs  the right-hand side {@code double[]}
546      * @return {@code this} instance.
547      */
548     public EqualsBuilder append(final double[] lhs, final double[] rhs) {
549         if (!isEquals) {
550             return this;
551         }
552         if (lhs == rhs) {
553             return this;
554         }
555         if (lhs == null || rhs == null) {
556             setEquals(false);
557             return this;
558         }
559         if (lhs.length != rhs.length) {
560             setEquals(false);
561             return this;
562         }
563         for (int i = 0; i < lhs.length && isEquals; ++i) {
564             append(lhs[i], rhs[i]);
565         }
566         return this;
567     }
568 
569     /**
570      * Test if two {@code float}s are equal by testing that the
571      * pattern of bits returned by doubleToLong are equal.
572      *
573      * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
574      *
575      * <p>It is compatible with the hash code generated by
576      * {@link HashCodeBuilder}.</p>
577      *
578      * @param lhs  the left-hand side {@code float}
579      * @param rhs  the right-hand side {@code float}
580      * @return {@code this} instance.
581      */
582     public EqualsBuilder append(final float lhs, final float rhs) {
583         if (isEquals) {
584             return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
585         }
586         return this;
587     }
588 
589     /**
590      * Deep comparison of array of {@code float}. Length and all
591      * values are compared.
592      *
593      * <p>The method {@link #append(float, float)} is used.</p>
594      *
595      * @param lhs  the left-hand side {@code float[]}
596      * @param rhs  the right-hand side {@code float[]}
597      * @return {@code this} instance.
598      */
599     public EqualsBuilder append(final float[] lhs, final float[] rhs) {
600         if (!isEquals) {
601             return this;
602         }
603         if (lhs == rhs) {
604             return this;
605         }
606         if (lhs == null || rhs == null) {
607             setEquals(false);
608             return this;
609         }
610         if (lhs.length != rhs.length) {
611             setEquals(false);
612             return this;
613         }
614         for (int i = 0; i < lhs.length && isEquals; ++i) {
615             append(lhs[i], rhs[i]);
616         }
617         return this;
618     }
619 
620     /**
621      * Test if two {@code int}s are equal.
622      *
623      * @param lhs  the left-hand side {@code int}
624      * @param rhs  the right-hand side {@code int}
625      * @return {@code this} instance.
626      */
627     public EqualsBuilder append(final int lhs, final int rhs) {
628         if (isEquals) {
629             isEquals = lhs == rhs;
630         }
631         return this;
632     }
633 
634     /**
635      * Deep comparison of array of {@code int}. Length and all
636      * values are compared.
637      *
638      * <p>The method {@link #append(int, int)} is used.</p>
639      *
640      * @param lhs  the left-hand side {@code int[]}
641      * @param rhs  the right-hand side {@code int[]}
642      * @return {@code this} instance.
643      */
644     public EqualsBuilder append(final int[] lhs, final int[] rhs) {
645         if (!isEquals) {
646             return this;
647         }
648         if (lhs == rhs) {
649             return this;
650         }
651         if (lhs == null || rhs == null) {
652             setEquals(false);
653             return this;
654         }
655         if (lhs.length != rhs.length) {
656             setEquals(false);
657             return this;
658         }
659         for (int i = 0; i < lhs.length && isEquals; ++i) {
660             append(lhs[i], rhs[i]);
661         }
662         return this;
663     }
664 
665     /**
666      * Test if two {@code long}s are equal.
667      *
668      * @param lhs
669      *                  the left-hand side {@code long}
670      * @param rhs
671      *                  the right-hand side {@code long}
672      * @return {@code this} instance.
673      */
674     public EqualsBuilder append(final long lhs, final long rhs) {
675         if (isEquals) {
676             isEquals = lhs == rhs;
677         }
678         return this;
679     }
680 
681     /**
682      * Deep comparison of array of {@code long}. Length and all
683      * values are compared.
684      *
685      * <p>The method {@link #append(long, long)} is used.</p>
686      *
687      * @param lhs  the left-hand side {@code long[]}
688      * @param rhs  the right-hand side {@code long[]}
689      * @return {@code this} instance.
690      */
691     public EqualsBuilder append(final long[] lhs, final long[] rhs) {
692         if (!isEquals) {
693             return this;
694         }
695         if (lhs == rhs) {
696             return this;
697         }
698         if (lhs == null || rhs == null) {
699             setEquals(false);
700             return this;
701         }
702         if (lhs.length != rhs.length) {
703             setEquals(false);
704             return this;
705         }
706         for (int i = 0; i < lhs.length && isEquals; ++i) {
707             append(lhs[i], rhs[i]);
708         }
709         return this;
710     }
711 
712     /**
713      * Test if two {@link Object}s are equal using either
714      * #{@link #reflectionAppend(Object, Object)}, if object are non
715      * primitives (or wrapper of primitives) or if field {@code testRecursive}
716      * is set to {@code false}. Otherwise, using their
717      * {@code equals} method.
718      *
719      * @param lhs  the left-hand side object
720      * @param rhs  the right-hand side object
721      * @return {@code this} instance.
722      */
723     public EqualsBuilder append(final Object lhs, final Object rhs) {
724         if (!isEquals) {
725             return this;
726         }
727         if (lhs == rhs) {
728             return this;
729         }
730         if (lhs == null || rhs == null) {
731             setEquals(false);
732             return this;
733         }
734         final Class<?> lhsClass = lhs.getClass();
735         if (lhsClass.isArray()) {
736             // factor out array case in order to keep method small enough
737             // to be inlined
738             appendArray(lhs, rhs);
739         } else // The simple case, not an array, just test the element
740         if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)) {
741             reflectionAppend(lhs, rhs);
742         } else {
743             isEquals = lhs.equals(rhs);
744         }
745         return this;
746     }
747 
748     /**
749      * Performs a deep comparison of two {@link Object} arrays.
750      *
751      * <p>This also will be called for the top level of
752      * multi-dimensional, ragged, and multi-typed arrays.</p>
753      *
754      * <p>Note that this method does not compare the type of the arrays; it only
755      * compares the contents.</p>
756      *
757      * @param lhs  the left-hand side {@code Object[]}
758      * @param rhs  the right-hand side {@code Object[]}
759      * @return {@code this} instance.
760      */
761     public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
762         if (!isEquals) {
763             return this;
764         }
765         if (lhs == rhs) {
766             return this;
767         }
768         if (lhs == null || rhs == null) {
769             setEquals(false);
770             return this;
771         }
772         if (lhs.length != rhs.length) {
773             setEquals(false);
774             return this;
775         }
776         for (int i = 0; i < lhs.length && isEquals; ++i) {
777             append(lhs[i], rhs[i]);
778         }
779         return this;
780     }
781 
782     /**
783      * Test if two {@code short}s are equal.
784      *
785      * @param lhs  the left-hand side {@code short}
786      * @param rhs  the right-hand side {@code short}
787      * @return {@code this} instance.
788      */
789     public EqualsBuilder append(final short lhs, final short rhs) {
790         if (isEquals) {
791             isEquals = lhs == rhs;
792         }
793         return this;
794     }
795 
796     /**
797      * Deep comparison of array of {@code short}. Length and all
798      * values are compared.
799      *
800      * <p>The method {@link #append(short, short)} is used.</p>
801      *
802      * @param lhs  the left-hand side {@code short[]}
803      * @param rhs  the right-hand side {@code short[]}
804      * @return {@code this} instance.
805      */
806     public EqualsBuilder append(final short[] lhs, final short[] rhs) {
807         if (!isEquals) {
808             return this;
809         }
810         if (lhs == rhs) {
811             return this;
812         }
813         if (lhs == null || rhs == null) {
814             setEquals(false);
815             return this;
816         }
817         if (lhs.length != rhs.length) {
818             setEquals(false);
819             return this;
820         }
821         for (int i = 0; i < lhs.length && isEquals; ++i) {
822             append(lhs[i], rhs[i]);
823         }
824         return this;
825     }
826 
827     /**
828      * Test if an {@link Object} is equal to an array.
829      *
830      * @param lhs  the left-hand side object, an array
831      * @param rhs  the right-hand side object
832      */
833     private void appendArray(final Object lhs, final Object rhs) {
834         // First we compare different dimensions, for example: a boolean[][] to a boolean[]
835         // then we 'Switch' on type of array, to dispatch to the correct handler
836         // This handles multidimensional arrays of the same depth
837         if (lhs.getClass() != rhs.getClass()) {
838             setEquals(false);
839         } else if (lhs instanceof long[]) {
840             append((long[]) lhs, (long[]) rhs);
841         } else if (lhs instanceof int[]) {
842             append((int[]) lhs, (int[]) rhs);
843         } else if (lhs instanceof short[]) {
844             append((short[]) lhs, (short[]) rhs);
845         } else if (lhs instanceof char[]) {
846             append((char[]) lhs, (char[]) rhs);
847         } else if (lhs instanceof byte[]) {
848             append((byte[]) lhs, (byte[]) rhs);
849         } else if (lhs instanceof double[]) {
850             append((double[]) lhs, (double[]) rhs);
851         } else if (lhs instanceof float[]) {
852             append((float[]) lhs, (float[]) rhs);
853         } else if (lhs instanceof boolean[]) {
854             append((boolean[]) lhs, (boolean[]) rhs);
855         } else {
856             // Not an array of primitives
857             append((Object[]) lhs, (Object[]) rhs);
858         }
859     }
860 
861     /**
862      * Adds the result of {@code super.equals()} to this builder.
863      *
864      * @param superEquals  the result of calling {@code super.equals()}
865      * @return {@code this} instance.
866      * @since 2.0
867      */
868     public EqualsBuilder appendSuper(final boolean superEquals) {
869         if (!isEquals) {
870             return this;
871         }
872         isEquals = superEquals;
873         return this;
874     }
875 
876     /**
877      * Returns {@code true} if the fields that have been checked
878      * are all equal.
879      *
880      * @return {@code true} if all of the fields that have been checked
881      *         are equal, {@code false} otherwise.
882      *
883      * @since 3.0
884      */
885     @Override
886     public Boolean build() {
887         return Boolean.valueOf(isEquals());
888     }
889 
890     /**
891      * Returns {@code true} if the fields that have been checked
892      * are all equal.
893      *
894      * @return boolean
895      */
896     public boolean isEquals() {
897         return isEquals;
898     }
899 
900     /**
901      * Tests if two {@code objects} by using reflection.
902      *
903      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
904      * fields. This means that it will throw a security exception if run under
905      * a security manager, if the permissions are not set up correctly. It is also
906      * not as efficient as testing explicitly. Non-primitive fields are compared using
907      * {@code equals()}.</p>
908      *
909      * <p>If the testTransients field is set to {@code true}, transient
910      * members will be tested, otherwise they are ignored, as they are likely
911      * derived fields, and not part of the value of the {@link Object}.</p>
912      *
913      * <p>Static fields will not be included. Superclass fields will be appended
914      * up to and including the specified superclass in field {@code reflectUpToClass}.
915      * A null superclass is treated as java.lang.Object.</p>
916      *
917      * <p>Field names listed in field {@code excludeFields} will be ignored.</p>
918      *
919      * <p>If either class of the compared objects is contained in
920      * {@code bypassReflectionClasses}, both objects are compared by calling
921      * the equals method of the left-hand side object with the right-hand side object as an argument.</p>
922      *
923      * @param lhs  the left-hand side object
924      * @param rhs  the right-hand side object
925      * @return {@code this} instance.
926      */
927     public EqualsBuilder reflectionAppend(final Object lhs, final Object rhs) {
928         if (!isEquals) {
929             return this;
930         }
931         if (lhs == rhs) {
932             return this;
933         }
934         if (lhs == null || rhs == null) {
935             isEquals = false;
936             return this;
937         }
938 
939         // Find the leaf class since there may be transients in the leaf
940         // class or in classes between the leaf and root.
941         // If we are not testing transients or a subclass has no ivars,
942         // then a subclass can test equals to a superclass.
943         final Class<?> lhsClass = lhs.getClass();
944         final Class<?> rhsClass = rhs.getClass();
945         Class<?> testClass;
946         if (lhsClass.isInstance(rhs)) {
947             testClass = lhsClass;
948             if (!rhsClass.isInstance(lhs)) {
949                 // rhsClass is a subclass of lhsClass
950                 testClass = rhsClass;
951             }
952         } else if (rhsClass.isInstance(lhs)) {
953             testClass = rhsClass;
954             if (!lhsClass.isInstance(rhs)) {
955                 // lhsClass is a subclass of rhsClass
956                 testClass = lhsClass;
957             }
958         } else {
959             // The two classes are not related.
960             isEquals = false;
961             return this;
962         }
963 
964         try {
965             if (testClass.isArray()) {
966                 append(lhs, rhs);
967             } else //If either class is being excluded, call normal object equals method on lhsClass.
968             if (bypassReflectionClasses != null
969                     && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))) {
970                 isEquals = lhs.equals(rhs);
971             } else {
972                 reflectionAppend(lhs, rhs, testClass);
973                 while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
974                     testClass = testClass.getSuperclass();
975                     reflectionAppend(lhs, rhs, testClass);
976                 }
977             }
978         } catch (final IllegalArgumentException e) {
979             // In this case, we tried to test a subclass vs. a superclass and
980             // the subclass has ivars or the ivars are transient and
981             // we are testing transients.
982             // If a subclass has ivars that we are trying to test them, we get an
983             // exception and we know that the objects are not equal.
984             isEquals = false;
985         }
986         return this;
987     }
988 
989     /**
990      * Appends the fields and values defined by the given object of the
991      * given Class.
992      *
993      * @param lhs  the left-hand side object
994      * @param rhs  the right-hand side object
995      * @param clazz  the class to append details of
996      */
997     private void reflectionAppend(
998         final Object lhs,
999         final Object rhs,
1000         final Class<?> clazz) {
1001 
1002         if (isRegistered(lhs, rhs)) {
1003             return;
1004         }
1005 
1006         try {
1007             register(lhs, rhs);
1008             final Field[] fields = clazz.getDeclaredFields();
1009             AccessibleObject.setAccessible(fields, true);
1010             for (int i = 0; i < fields.length && isEquals; i++) {
1011                 final Field field = fields[i];
1012                 if (!ArrayUtils.contains(excludeFields, field.getName())
1013                     && !field.getName().contains("$")
1014                     && (testTransients || !Modifier.isTransient(field.getModifiers()))
1015                     && !Modifier.isStatic(field.getModifiers())
1016                     && !field.isAnnotationPresent(EqualsExclude.class)) {
1017                     append(Reflection.getUnchecked(field, lhs), Reflection.getUnchecked(field, rhs));
1018                 }
1019             }
1020         } finally {
1021             unregister(lhs, rhs);
1022         }
1023     }
1024 
1025     /**
1026      * Reset the EqualsBuilder so you can use the same object again.
1027      *
1028      * @since 2.5
1029      */
1030     public void reset() {
1031         isEquals = true;
1032     }
1033 
1034     /**
1035      * Sets {@link Class}es whose instances should be compared by calling their {@code equals}
1036      * although being in recursive mode. So the fields of theses classes will not be compared recursively by reflection.
1037      *
1038      * <p>Here you should name classes having non-transient fields which are cache fields being set lazily.<br>
1039      * Prominent example being {@link String} class with its hash code cache field. Due to the importance
1040      * of the {@link String} class, it is included in the default bypasses classes. Usually, if you use
1041      * your own set of classes here, remember to include {@link String} class, too.</p>
1042      *
1043      * @param bypassReflectionClasses  classes to bypass reflection test
1044      * @return {@code this} instance.
1045      * @see #setTestRecursive(boolean)
1046      * @since 3.8
1047      */
1048     public EqualsBuilder setBypassReflectionClasses(final List<Class<?>> bypassReflectionClasses) {
1049         this.bypassReflectionClasses = bypassReflectionClasses;
1050         return this;
1051     }
1052 
1053     /**
1054      * Sets the {@code isEquals} value.
1055      *
1056      * @param isEquals The value to set.
1057      * @since 2.1
1058      */
1059     protected void setEquals(final boolean isEquals) {
1060         this.isEquals = isEquals;
1061     }
1062 
1063     /**
1064      * Sets field names to be excluded by reflection tests.
1065      *
1066      * @param excludeFields the fields to exclude
1067      * @return {@code this} instance.
1068      * @since 3.6
1069      */
1070     public EqualsBuilder setExcludeFields(final String... excludeFields) {
1071         this.excludeFields = excludeFields;
1072         return this;
1073     }
1074 
1075     /**
1076      * Sets the superclass to reflect up to at reflective tests.
1077      *
1078      * @param reflectUpToClass the super class to reflect up to
1079      * @return {@code this} instance.
1080      * @since 3.6
1081      */
1082     public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass) {
1083         this.reflectUpToClass = reflectUpToClass;
1084         return this;
1085     }
1086 
1087     /**
1088      * Sets whether to test fields recursively, instead of using their equals method, when reflectively comparing objects.
1089      * String objects, which cache a hash value, are automatically excluded from recursive testing.
1090      * You may specify other exceptions by calling {@link #setBypassReflectionClasses(List)}.
1091      *
1092      * @param testRecursive whether to do a recursive test
1093      * @return {@code this} instance.
1094      * @see #setBypassReflectionClasses(List)
1095      * @since 3.6
1096      */
1097     public EqualsBuilder setTestRecursive(final boolean testRecursive) {
1098         this.testRecursive = testRecursive;
1099         return this;
1100     }
1101 
1102     /**
1103      * Sets whether to include transient fields when reflectively comparing objects.
1104      *
1105      * @param testTransients whether to test transient fields
1106      * @return {@code this} instance.
1107      * @since 3.6
1108      */
1109     public EqualsBuilder setTestTransients(final boolean testTransients) {
1110         this.testTransients = testTransients;
1111         return this;
1112     }
1113 }