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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    *      https://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;
18  
19  import java.util.Arrays;
20  import java.util.Collections;
21  import java.util.List;
22  import java.util.function.Consumer;
23  
24  import org.apache.commons.lang3.math.NumberUtils;
25  
26  /**
27   * Operations on boolean primitives and Boolean objects.
28   *
29   * <p>This class tries to handle {@code null} input gracefully.
30   * An exception will not be thrown for a {@code null} input.
31   * Each method documents its behavior in more detail.</p>
32   *
33   * <p>#ThreadSafe#</p>
34   *
35   * @since 2.0
36   */
37  public class BooleanUtils {
38  
39      private static final List<Boolean> BOOLEAN_LIST = Collections.unmodifiableList(Arrays.asList(Boolean.FALSE, Boolean.TRUE));
40  
41      /**
42       * The false String {@code "false"}.
43       *
44       * @since 3.12.0
45       */
46      public static final String FALSE = "false";
47  
48      /**
49       * The no String {@code "no"}.
50       *
51       * @since 3.12.0
52       */
53      public static final String NO = "no";
54  
55      /**
56       * The off String {@code "off"}.
57       *
58       * @since 3.12.0
59       */
60      public static final String OFF = "off";
61  
62      /**
63       * The on String {@code "on"}.
64       *
65       * @since 3.12.0
66       */
67      public static final String ON = "on";
68  
69      /**
70       * The true String {@code "true"}.
71       *
72       * @since 3.12.0
73       */
74      public static final String TRUE = "true";
75  
76      /**
77       * The yes String {@code "yes"}.
78       *
79       * @since 3.12.0
80       */
81      public static final String YES = "yes";
82  
83      /**
84       * Performs an 'and' operation on a set of booleans.
85       *
86       * <pre>
87       *   BooleanUtils.and(true, true)         = true
88       *   BooleanUtils.and(false, false)       = false
89       *   BooleanUtils.and(true, false)        = false
90       *   BooleanUtils.and(true, true, false)  = false
91       *   BooleanUtils.and(true, true, true)   = true
92       * </pre>
93       *
94       * @param array  an array of {@code boolean}s
95       * @return the result of the logical 'and' operation. That is {@code false}
96       * if any of the parameters is {@code false} and {@code true} otherwise.
97       * @throws NullPointerException if {@code array} is {@code null}
98       * @throws IllegalArgumentException if {@code array} is empty.
99       * @since 3.0.1
100      */
101     public static boolean and(final boolean... array) {
102         ObjectUtils.requireNonEmpty(array, "array");
103         for (final boolean element : array) {
104             if (!element) {
105                 return false;
106             }
107         }
108         return true;
109     }
110 
111     /**
112      * Performs an 'and' operation on an array of Booleans.
113      * <pre>
114      *   BooleanUtils.and(Boolean.TRUE, Boolean.TRUE)                 = Boolean.TRUE
115      *   BooleanUtils.and(Boolean.FALSE, Boolean.FALSE)               = Boolean.FALSE
116      *   BooleanUtils.and(Boolean.TRUE, Boolean.FALSE)                = Boolean.FALSE
117      *   BooleanUtils.and(Boolean.TRUE, Boolean.TRUE, Boolean.TRUE)   = Boolean.TRUE
118      *   BooleanUtils.and(Boolean.FALSE, Boolean.FALSE, Boolean.TRUE) = Boolean.FALSE
119      *   BooleanUtils.and(Boolean.TRUE, Boolean.FALSE, Boolean.TRUE)  = Boolean.FALSE
120      *   BooleanUtils.and(null, null)                                 = Boolean.FALSE
121      * </pre>
122      * <p>
123      * Null array elements map to false, like {@code Boolean.parseBoolean(null)} and its callers return false.
124      * </p>
125      *
126      * @param array  an array of {@link Boolean}s
127      * @return the result of the logical 'and' operation. That is {@code false}
128      * if any of the parameters is {@code false} and {@code true} otherwise.
129      * @throws NullPointerException if {@code array} is {@code null}
130      * @throws IllegalArgumentException if {@code array} is empty.
131      * @since 3.0.1
132      */
133     public static Boolean and(final Boolean... array) {
134         ObjectUtils.requireNonEmpty(array, "array");
135         return and(ArrayUtils.toPrimitive(array)) ? Boolean.TRUE : Boolean.FALSE;
136     }
137 
138     /**
139      * Returns a new array of possible values (like an enum would).
140      *
141      * @return a new array of possible values (like an enum would).
142      * @since 3.12.0
143      */
144     public static Boolean[] booleanValues() {
145         return new Boolean[] {Boolean.FALSE, Boolean.TRUE};
146     }
147 
148     /**
149      * Compares two {@code boolean} values. This is the same functionality as provided in Java 7.
150      *
151      * @param x the first {@code boolean} to compare
152      * @param y the second {@code boolean} to compare
153      * @return the value {@code 0} if {@code x == y};
154      *         a value less than {@code 0} if {@code !x && y}; and
155      *         a value greater than {@code 0} if {@code x && !y}
156      * @since 3.4
157      */
158     public static int compare(final boolean x, final boolean y) {
159         if (x == y) {
160             return 0;
161         }
162         return x ? 1 : -1;
163     }
164 
165     /**
166      * Performs the given action for each Boolean {@link BooleanUtils#values()}.
167      *
168      * @param action The action to be performed for each element
169      * @since 3.13.0
170      */
171     public static void forEach(final Consumer<Boolean> action) {
172         values().forEach(action);
173     }
174 
175     /**
176      * Checks if a {@link Boolean} value is {@code false},
177      * handling {@code null} by returning {@code false}.
178      *
179      * <pre>
180      *   BooleanUtils.isFalse(Boolean.TRUE)  = false
181      *   BooleanUtils.isFalse(Boolean.FALSE) = true
182      *   BooleanUtils.isFalse(null)          = false
183      * </pre>
184      *
185      * @param bool  the boolean to check, null returns {@code false}
186      * @return {@code true} only if the input is non-{@code null} and {@code false}
187      * @since 2.1
188      */
189     public static boolean isFalse(final Boolean bool) {
190         return Boolean.FALSE.equals(bool);
191     }
192 
193     /**
194      * Checks if a {@link Boolean} value is <em>not</em> {@code false},
195      * handling {@code null} by returning {@code true}.
196      *
197      * <pre>
198      *   BooleanUtils.isNotFalse(Boolean.TRUE)  = true
199      *   BooleanUtils.isNotFalse(Boolean.FALSE) = false
200      *   BooleanUtils.isNotFalse(null)          = true
201      * </pre>
202      *
203      * @param bool  the boolean to check, null returns {@code true}
204      * @return {@code true} if the input is {@code null} or {@code true}
205      * @since 2.3
206      */
207     public static boolean isNotFalse(final Boolean bool) {
208         return !isFalse(bool);
209     }
210 
211     /**
212      * Checks if a {@link Boolean} value is <em>not</em> {@code true},
213      * handling {@code null} by returning {@code true}.
214      *
215      * <pre>
216      *   BooleanUtils.isNotTrue(Boolean.TRUE)  = false
217      *   BooleanUtils.isNotTrue(Boolean.FALSE) = true
218      *   BooleanUtils.isNotTrue(null)          = true
219      * </pre>
220      *
221      * @param bool  the boolean to check, null returns {@code true}
222      * @return {@code true} if the input is null or false
223      * @since 2.3
224      */
225     public static boolean isNotTrue(final Boolean bool) {
226         return !isTrue(bool);
227     }
228 
229     /**
230      * Checks if a {@link Boolean} value is {@code true},
231      * handling {@code null} by returning {@code false}.
232      *
233      * <pre>
234      *   BooleanUtils.isTrue(Boolean.TRUE)  = true
235      *   BooleanUtils.isTrue(Boolean.FALSE) = false
236      *   BooleanUtils.isTrue(null)          = false
237      * </pre>
238      *
239      * @param bool the boolean to check, {@code null} returns {@code false}
240      * @return {@code true} only if the input is non-null and true
241      * @since 2.1
242      */
243     public static boolean isTrue(final Boolean bool) {
244         return Boolean.TRUE.equals(bool);
245     }
246 
247     /**
248      * Negates the specified boolean.
249      *
250      * <p>If {@code null} is passed in, {@code null} will be returned.</p>
251      *
252      * <p>NOTE: This returns {@code null} and will throw a {@link NullPointerException}
253      * if unboxed to a boolean.</p>
254      *
255      * <pre>
256      *   BooleanUtils.negate(Boolean.TRUE)  = Boolean.FALSE;
257      *   BooleanUtils.negate(Boolean.FALSE) = Boolean.TRUE;
258      *   BooleanUtils.negate(null)          = null;
259      * </pre>
260      *
261      * @param bool  the Boolean to negate, may be null
262      * @return the negated Boolean, or {@code null} if {@code null} input
263      */
264     public static Boolean negate(final Boolean bool) {
265         if (bool == null) {
266             return null;
267         }
268         return bool.booleanValue() ? Boolean.FALSE : Boolean.TRUE;
269     }
270 
271     /**
272      * Performs a one-hot on an array of booleans.
273      * <p>
274      * This implementation returns true if one, and only one, of the supplied values is true.
275      * </p>
276      * <p>
277      * See also <a href="https://en.wikipedia.org/wiki/One-hot">One-hot</a>.
278      * </p>
279      *
280      * @param array  an array of {@code boolean}s
281      * @return the result of the one-hot operations
282      * @throws NullPointerException if {@code array} is {@code null}
283      * @throws IllegalArgumentException if {@code array} is empty.
284      */
285     public static boolean oneHot(final boolean... array) {
286         ObjectUtils.requireNonEmpty(array, "array");
287         boolean result = false;
288         for (final boolean element: array) {
289             if (element) {
290                 if (result) {
291                     return false;
292                 }
293                 result = true;
294             }
295         }
296         return result;
297     }
298 
299     /**
300      * Performs a one-hot on an array of booleans.
301      * <p>
302      * This implementation returns true if one, and only one, of the supplied values is true.
303      * </p>
304      * <p>
305      * Null array elements map to false, like {@code Boolean.parseBoolean(null)} and its callers return false.
306      * </p>
307      * <p>
308      * See also <a href="https://en.wikipedia.org/wiki/One-hot">One-hot</a>.
309      * </p>
310      *
311      * @param array  an array of {@code boolean}s
312      * @return the result of the one-hot operations
313      * @throws NullPointerException if {@code array} is {@code null}
314      * @throws IllegalArgumentException if {@code array} is empty.
315      */
316     public static Boolean oneHot(final Boolean... array) {
317         return Boolean.valueOf(oneHot(ArrayUtils.toPrimitive(array)));
318     }
319 
320     /**
321      * Performs an 'or' operation on a set of booleans.
322      *
323      * <pre>
324      *   BooleanUtils.or(true, true)          = true
325      *   BooleanUtils.or(false, false)        = false
326      *   BooleanUtils.or(true, false)         = true
327      *   BooleanUtils.or(true, true, false)   = true
328      *   BooleanUtils.or(true, true, true)    = true
329      *   BooleanUtils.or(false, false, false) = false
330      * </pre>
331      *
332      * @param array  an array of {@code boolean}s
333      * @return {@code true} if any of the arguments is {@code true}, and it returns {@code false} otherwise.
334      * @throws NullPointerException if {@code array} is {@code null}
335      * @throws IllegalArgumentException if {@code array} is empty.
336      * @since 3.0.1
337      */
338     public static boolean or(final boolean... array) {
339         ObjectUtils.requireNonEmpty(array, "array");
340         for (final boolean element : array) {
341             if (element) {
342                 return true;
343             }
344         }
345         return false;
346     }
347 
348     /**
349      * Performs an 'or' operation on an array of Booleans.
350      * <pre>
351      *   BooleanUtils.or(Boolean.TRUE, Boolean.TRUE)                  = Boolean.TRUE
352      *   BooleanUtils.or(Boolean.FALSE, Boolean.FALSE)                = Boolean.FALSE
353      *   BooleanUtils.or(Boolean.TRUE, Boolean.FALSE)                 = Boolean.TRUE
354      *   BooleanUtils.or(Boolean.TRUE, Boolean.TRUE, Boolean.TRUE)    = Boolean.TRUE
355      *   BooleanUtils.or(Boolean.FALSE, Boolean.FALSE, Boolean.TRUE)  = Boolean.TRUE
356      *   BooleanUtils.or(Boolean.TRUE, Boolean.FALSE, Boolean.TRUE)   = Boolean.TRUE
357      *   BooleanUtils.or(Boolean.FALSE, Boolean.FALSE, Boolean.FALSE) = Boolean.FALSE
358      *   BooleanUtils.or(Boolean.TRUE, null)                          = Boolean.TRUE
359      *   BooleanUtils.or(Boolean.FALSE, null)                         = Boolean.FALSE
360      * </pre>
361      * <p>
362      * Null array elements map to false, like {@code Boolean.parseBoolean(null)} and its callers return false.
363      * </p>
364      *
365      * @param array  an array of {@link Boolean}s
366      * @return {@code true} if any of the arguments is {@code true}, and it returns {@code false} otherwise.
367      * @throws NullPointerException if {@code array} is {@code null}
368      * @throws IllegalArgumentException if {@code array} is empty.
369      * @since 3.0.1
370      */
371     public static Boolean or(final Boolean... array) {
372         ObjectUtils.requireNonEmpty(array, "array");
373         return or(ArrayUtils.toPrimitive(array)) ? Boolean.TRUE : Boolean.FALSE;
374     }
375 
376     /**
377      * Returns a new array of possible values (like an enum would).
378      *
379      * @return a new array of possible values (like an enum would).
380      * @since 3.12.0
381      */
382     public static boolean[] primitiveValues() {
383         return new boolean[] {false, true};
384     }
385 
386     /**
387      * Converts a Boolean to a boolean handling {@code null}
388      * by returning {@code false}.
389      *
390      * <pre>
391      *   BooleanUtils.toBoolean(Boolean.TRUE)  = true
392      *   BooleanUtils.toBoolean(Boolean.FALSE) = false
393      *   BooleanUtils.toBoolean(null)          = false
394      * </pre>
395      *
396      * @param bool  the boolean to convert
397      * @return {@code true} or {@code false}, {@code null} returns {@code false}
398      */
399     public static boolean toBoolean(final Boolean bool) {
400         return bool != null && bool.booleanValue();
401     }
402 
403     /**
404      * Converts an int to a boolean using the convention that {@code zero}
405      * is {@code false}, everything else is {@code true}.
406      *
407      * <pre>
408      *   BooleanUtils.toBoolean(0) = false
409      *   BooleanUtils.toBoolean(1) = true
410      *   BooleanUtils.toBoolean(2) = true
411      * </pre>
412      *
413      * @param value  the int to convert
414      * @return {@code true} if non-zero, {@code false}
415      *  if zero
416      */
417     public static boolean toBoolean(final int value) {
418         return value != 0;
419     }
420 
421     /**
422      * Converts an int to a boolean specifying the conversion values.
423      *
424      * <p>If the {@code trueValue} and {@code falseValue} are the same number then
425      * the return value will be {@code true} in case {@code value} matches it.</p>
426      *
427      * <pre>
428      *   BooleanUtils.toBoolean(0, 1, 0) = false
429      *   BooleanUtils.toBoolean(1, 1, 0) = true
430      *   BooleanUtils.toBoolean(1, 1, 1) = true
431      *   BooleanUtils.toBoolean(2, 1, 2) = false
432      *   BooleanUtils.toBoolean(2, 2, 0) = true
433      * </pre>
434      *
435      * @param value  the {@link Integer} to convert
436      * @param trueValue  the value to match for {@code true}
437      * @param falseValue  the value to match for {@code false}
438      * @return {@code true} or {@code false}
439      * @throws IllegalArgumentException if {@code value} does not match neither
440      * {@code trueValue} no {@code falseValue}
441      */
442     public static boolean toBoolean(final int value, final int trueValue, final int falseValue) {
443         if (value == trueValue) {
444             return true;
445         }
446         if (value == falseValue) {
447             return false;
448         }
449         throw new IllegalArgumentException("The Integer did not match either specified value");
450     }
451 
452     /**
453      * Converts an Integer to a boolean specifying the conversion values.
454      *
455      * <pre>
456      *   BooleanUtils.toBoolean(Integer.valueOf(0), Integer.valueOf(1), Integer.valueOf(0)) = false
457      *   BooleanUtils.toBoolean(Integer.valueOf(1), Integer.valueOf(1), Integer.valueOf(0)) = true
458      *   BooleanUtils.toBoolean(Integer.valueOf(2), Integer.valueOf(1), Integer.valueOf(2)) = false
459      *   BooleanUtils.toBoolean(Integer.valueOf(2), Integer.valueOf(2), Integer.valueOf(0)) = true
460      *   BooleanUtils.toBoolean(null, null, Integer.valueOf(0))                     = true
461      * </pre>
462      *
463      * @param value  the Integer to convert
464      * @param trueValue  the value to match for {@code true}, may be {@code null}
465      * @param falseValue  the value to match for {@code false}, may be {@code null}
466      * @return {@code true} or {@code false}
467      * @throws IllegalArgumentException if no match
468      */
469     public static boolean toBoolean(final Integer value, final Integer trueValue, final Integer falseValue) {
470         if (value == null) {
471             if (trueValue == null) {
472                 return true;
473             }
474             if (falseValue == null) {
475                 return false;
476             }
477         } else if (value.equals(trueValue)) {
478             return true;
479         } else if (value.equals(falseValue)) {
480             return false;
481         }
482         throw new IllegalArgumentException("The Integer did not match either specified value");
483     }
484 
485     /**
486      * Converts a String to a boolean (optimized for performance).
487      *
488      * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'} or {@code 'yes'}
489      * (case insensitive) will return {@code true}. Otherwise,
490      * {@code false} is returned.</p>
491      *
492      * <p>This method performs 4 times faster (JDK1.4) than
493      * {@code Boolean.valueOf(String)}. However, this method accepts
494      * 'on' and 'yes', 't', 'y' as true values.
495      *
496      * <pre>
497      *   BooleanUtils.toBoolean(null)    = false
498      *   BooleanUtils.toBoolean("true")  = true
499      *   BooleanUtils.toBoolean("TRUE")  = true
500      *   BooleanUtils.toBoolean("tRUe")  = true
501      *   BooleanUtils.toBoolean("on")    = true
502      *   BooleanUtils.toBoolean("yes")   = true
503      *   BooleanUtils.toBoolean("false") = false
504      *   BooleanUtils.toBoolean("x gti") = false
505      *   BooleanUtils.toBoolean("y") = true
506      *   BooleanUtils.toBoolean("n") = false
507      *   BooleanUtils.toBoolean("t") = true
508      *   BooleanUtils.toBoolean("f") = false
509      * </pre>
510      *
511      * @param str  the String to check
512      * @return the boolean value of the string, {@code false} if no match or the String is null
513      */
514     public static boolean toBoolean(final String str) {
515         return toBooleanObject(str) == Boolean.TRUE;
516     }
517 
518     /**
519      * Converts a String to a Boolean throwing an exception if no match found.
520      *
521      * <pre>
522      *   BooleanUtils.toBoolean("true", "true", "false")  = true
523      *   BooleanUtils.toBoolean("false", "true", "false") = false
524      * </pre>
525      *
526      * @param str  the String to check
527      * @param trueString  the String to match for {@code true} (case-sensitive), may be {@code null}
528      * @param falseString  the String to match for {@code false} (case-sensitive), may be {@code null}
529      * @return the boolean value of the string
530      * @throws IllegalArgumentException if the String doesn't match
531      */
532     public static boolean toBoolean(final String str, final String trueString, final String falseString) {
533         if (str == trueString) {
534             return true;
535         }
536         if (str == falseString) {
537             return false;
538         }
539         if (str != null) {
540             if (str.equals(trueString)) {
541                 return true;
542             }
543             if (str.equals(falseString)) {
544                 return false;
545             }
546         }
547         throw new IllegalArgumentException("The String did not match either specified value");
548     }
549 
550     /**
551      * Converts a Boolean to a boolean handling {@code null}.
552      *
553      * <pre>
554      *   BooleanUtils.toBooleanDefaultIfNull(Boolean.TRUE, false)  = true
555      *   BooleanUtils.toBooleanDefaultIfNull(Boolean.TRUE, true)   = true
556      *   BooleanUtils.toBooleanDefaultIfNull(Boolean.FALSE, true)  = false
557      *   BooleanUtils.toBooleanDefaultIfNull(Boolean.FALSE, false) = false
558      *   BooleanUtils.toBooleanDefaultIfNull(null, true)           = true
559      *   BooleanUtils.toBooleanDefaultIfNull(null, false)          = false
560      * </pre>
561      *
562      * @param bool  the boolean object to convert to primitive
563      * @param valueIfNull  the boolean value to return if the parameter {@code bool} is {@code null}
564      * @return {@code true} or {@code false}
565      */
566     public static boolean toBooleanDefaultIfNull(final Boolean bool, final boolean valueIfNull) {
567         if (bool == null) {
568             return valueIfNull;
569         }
570         return bool.booleanValue();
571     }
572 
573     /**
574      * Converts an int to a Boolean using the convention that {@code zero}
575      * is {@code false}, everything else is {@code true}.
576      *
577      * <pre>
578      *   BooleanUtils.toBoolean(0) = Boolean.FALSE
579      *   BooleanUtils.toBoolean(1) = Boolean.TRUE
580      *   BooleanUtils.toBoolean(2) = Boolean.TRUE
581      * </pre>
582      *
583      * @param value  the int to convert
584      * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
585      *  {@code null} if {@code null}
586      */
587     public static Boolean toBooleanObject(final int value) {
588         return value == 0 ? Boolean.FALSE : Boolean.TRUE;
589     }
590 
591     /**
592      * Converts an int to a Boolean specifying the conversion values.
593      *
594      * <p>NOTE: This method may return {@code null} and may throw a {@link NullPointerException}
595      * if unboxed to a {@code boolean}.</p>
596      *
597      * <p>The checks are done first for the {@code trueValue}, then for the {@code falseValue} and
598      * finally for the {@code nullValue}.</p>
599      *
600      * <pre>
601      *   BooleanUtils.toBooleanObject(0, 0, 2, 3) = Boolean.TRUE
602      *   BooleanUtils.toBooleanObject(0, 0, 0, 3) = Boolean.TRUE
603      *   BooleanUtils.toBooleanObject(0, 0, 0, 0) = Boolean.TRUE
604      *   BooleanUtils.toBooleanObject(2, 1, 2, 3) = Boolean.FALSE
605      *   BooleanUtils.toBooleanObject(2, 1, 2, 2) = Boolean.FALSE
606      *   BooleanUtils.toBooleanObject(3, 1, 2, 3) = null
607      * </pre>
608      *
609      * @param value  the Integer to convert
610      * @param trueValue  the value to match for {@code true}
611      * @param falseValue  the value to match for {@code false}
612      * @param nullValue  the value to match for {@code null}
613      * @return Boolean.TRUE, Boolean.FALSE, or {@code null}
614      * @throws IllegalArgumentException if no match
615      */
616     public static Boolean toBooleanObject(final int value, final int trueValue, final int falseValue, final int nullValue) {
617         if (value == trueValue) {
618             return Boolean.TRUE;
619         }
620         if (value == falseValue) {
621             return Boolean.FALSE;
622         }
623         if (value == nullValue) {
624             return null;
625         }
626         throw new IllegalArgumentException("The Integer did not match any specified value");
627     }
628 
629     /**
630      * Converts an Integer to a Boolean using the convention that {@code zero}
631      * is {@code false}, every other numeric value is {@code true}.
632      *
633      * <p>{@code null} will be converted to {@code null}.</p>
634      *
635      * <p>NOTE: This method may return {@code null} and may throw a {@link NullPointerException}
636      * if unboxed to a {@code boolean}.</p>
637      *
638      * <pre>
639      *   BooleanUtils.toBooleanObject(Integer.valueOf(0))    = Boolean.FALSE
640      *   BooleanUtils.toBooleanObject(Integer.valueOf(1))    = Boolean.TRUE
641      *   BooleanUtils.toBooleanObject(Integer.valueOf(null)) = null
642      * </pre>
643      *
644      * @param value  the Integer to convert
645      * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
646      *  {@code null} if {@code null} input
647      */
648     public static Boolean toBooleanObject(final Integer value) {
649         if (value == null) {
650             return null;
651         }
652         return value.intValue() == 0 ? Boolean.FALSE : Boolean.TRUE;
653     }
654 
655     /**
656      * Converts an Integer to a Boolean specifying the conversion values.
657      *
658      * <p>NOTE: This method may return {@code null} and may throw a {@link NullPointerException}
659      * if unboxed to a {@code boolean}.</p>
660      *
661      * <p>The checks are done first for the {@code trueValue}, then for the {@code falseValue} and
662      * finally for the {@code nullValue}.</p>
663      **
664      * <pre>
665      *   BooleanUtils.toBooleanObject(Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(2), Integer.valueOf(3)) = Boolean.TRUE
666      *   BooleanUtils.toBooleanObject(Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(3)) = Boolean.TRUE
667      *   BooleanUtils.toBooleanObject(Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(0)) = Boolean.TRUE
668      *   BooleanUtils.toBooleanObject(Integer.valueOf(2), Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3)) = Boolean.FALSE
669      *   BooleanUtils.toBooleanObject(Integer.valueOf(2), Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(2)) = Boolean.FALSE
670      *   BooleanUtils.toBooleanObject(Integer.valueOf(3), Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3)) = null
671      * </pre>
672      *
673      * @param value  the Integer to convert
674      * @param trueValue  the value to match for {@code true}, may be {@code null}
675      * @param falseValue  the value to match for {@code false}, may be {@code null}
676      * @param nullValue  the value to match for {@code null}, may be {@code null}
677      * @return Boolean.TRUE, Boolean.FALSE, or {@code null}
678      * @throws IllegalArgumentException if no match
679      */
680     public static Boolean toBooleanObject(final Integer value, final Integer trueValue, final Integer falseValue, final Integer nullValue) {
681         if (value == null) {
682             if (trueValue == null) {
683                 return Boolean.TRUE;
684             }
685             if (falseValue == null) {
686                 return Boolean.FALSE;
687             }
688             if (nullValue == null) {
689                 return null;
690             }
691         } else if (value.equals(trueValue)) {
692             return Boolean.TRUE;
693         } else if (value.equals(falseValue)) {
694             return Boolean.FALSE;
695         } else if (value.equals(nullValue)) {
696             return null;
697         }
698         throw new IllegalArgumentException("The Integer did not match any specified value");
699     }
700 
701     /**
702      * Converts a String to a Boolean.
703      *
704      * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'}, {@code 'yes'}
705      * or {@code '1'} (case insensitive) will return {@code true}.
706      * {@code 'false'}, {@code 'off'}, {@code 'n'}, {@code 'f'}, {@code 'no'}
707      * or {@code '0'} (case insensitive) will return {@code false}.
708      * Otherwise, {@code null} is returned.</p>
709      *
710      * <p>NOTE: This method may return {@code null} and may throw a {@link NullPointerException}
711      * if unboxed to a {@code boolean}.</p>
712      *
713      * <pre>
714      *   // Case is not significant
715      *   BooleanUtils.toBooleanObject(null)    = null
716      *   BooleanUtils.toBooleanObject("true")  = Boolean.TRUE
717      *   BooleanUtils.toBooleanObject("T")     = Boolean.TRUE // i.e. T[RUE]
718      *   BooleanUtils.toBooleanObject("false") = Boolean.FALSE
719      *   BooleanUtils.toBooleanObject("f")     = Boolean.FALSE // i.e. f[alse]
720      *   BooleanUtils.toBooleanObject("No")    = Boolean.FALSE
721      *   BooleanUtils.toBooleanObject("n")     = Boolean.FALSE // i.e. n[o]
722      *   BooleanUtils.toBooleanObject("on")    = Boolean.TRUE
723      *   BooleanUtils.toBooleanObject("ON")    = Boolean.TRUE
724      *   BooleanUtils.toBooleanObject("off")   = Boolean.FALSE
725      *   BooleanUtils.toBooleanObject("oFf")   = Boolean.FALSE
726      *   BooleanUtils.toBooleanObject("yes")   = Boolean.TRUE
727      *   BooleanUtils.toBooleanObject("Y")     = Boolean.TRUE // i.e. Y[ES]
728      *   BooleanUtils.toBooleanObject("1")     = Boolean.TRUE
729      *   BooleanUtils.toBooleanObject("0")     = Boolean.FALSE
730      *   BooleanUtils.toBooleanObject("blue")  = null
731      *   BooleanUtils.toBooleanObject("true ") = null // trailing space (too long)
732      *   BooleanUtils.toBooleanObject("ono")   = null // does not match on or no
733      * </pre>
734      *
735      * @param str  the String to check; upper and lower case are treated as the same
736      * @return the Boolean value of the string, {@code null} if no match or {@code null} input
737      */
738     public static Boolean toBooleanObject(final String str) {
739         // Previously used equalsIgnoreCase, which was fast for interned 'true'.
740         // Non interned 'true' matched 15 times slower.
741         //
742         // Optimization provides same performance as before for interned 'true'.
743         // Similar performance for null, 'false', and other strings not length 2/3/4.
744         // 'true'/'TRUE' match 4 times slower, 'tRUE'/'True' 7 times slower.
745         if (str == TRUE) {
746             return Boolean.TRUE;
747         }
748         if (str == null) {
749             return null;
750         }
751         switch (str.length()) {
752             case 1: {
753                 final char ch0 = str.charAt(0);
754                 if (ch0 == 'y' || ch0 == 'Y' ||
755                     ch0 == 't' || ch0 == 'T' ||
756                     ch0 == '1') {
757                     return Boolean.TRUE;
758                 }
759                 if (ch0 == 'n' || ch0 == 'N' ||
760                     ch0 == 'f' || ch0 == 'F' ||
761                     ch0 == '0') {
762                     return Boolean.FALSE;
763                 }
764                 break;
765             }
766             case 2: {
767                 final char ch0 = str.charAt(0);
768                 final char ch1 = str.charAt(1);
769                 if ((ch0 == 'o' || ch0 == 'O') &&
770                     (ch1 == 'n' || ch1 == 'N')) {
771                     return Boolean.TRUE;
772                 }
773                 if ((ch0 == 'n' || ch0 == 'N') &&
774                     (ch1 == 'o' || ch1 == 'O')) {
775                     return Boolean.FALSE;
776                 }
777                 break;
778             }
779             case 3: {
780                 final char ch0 = str.charAt(0);
781                 final char ch1 = str.charAt(1);
782                 final char ch2 = str.charAt(2);
783                 if ((ch0 == 'y' || ch0 == 'Y') &&
784                     (ch1 == 'e' || ch1 == 'E') &&
785                     (ch2 == 's' || ch2 == 'S')) {
786                     return Boolean.TRUE;
787                 }
788                 if ((ch0 == 'o' || ch0 == 'O') &&
789                     (ch1 == 'f' || ch1 == 'F') &&
790                     (ch2 == 'f' || ch2 == 'F')) {
791                     return Boolean.FALSE;
792                 }
793                 break;
794             }
795             case 4: {
796                 final char ch0 = str.charAt(0);
797                 final char ch1 = str.charAt(1);
798                 final char ch2 = str.charAt(2);
799                 final char ch3 = str.charAt(3);
800                 if ((ch0 == 't' || ch0 == 'T') &&
801                     (ch1 == 'r' || ch1 == 'R') &&
802                     (ch2 == 'u' || ch2 == 'U') &&
803                     (ch3 == 'e' || ch3 == 'E')) {
804                     return Boolean.TRUE;
805                 }
806                 break;
807             }
808             case 5: {
809                 final char ch0 = str.charAt(0);
810                 final char ch1 = str.charAt(1);
811                 final char ch2 = str.charAt(2);
812                 final char ch3 = str.charAt(3);
813                 final char ch4 = str.charAt(4);
814                 if ((ch0 == 'f' || ch0 == 'F') &&
815                     (ch1 == 'a' || ch1 == 'A') &&
816                     (ch2 == 'l' || ch2 == 'L') &&
817                     (ch3 == 's' || ch3 == 'S') &&
818                     (ch4 == 'e' || ch4 == 'E')) {
819                     return Boolean.FALSE;
820                 }
821                 break;
822             }
823         default:
824             break;
825         }
826 
827         return null;
828     }
829 
830     /**
831      * Converts a String to a Boolean throwing an exception if no match.
832      *
833      * <p>NOTE: This method may return {@code null} and may throw a {@link NullPointerException}
834      * if unboxed to a {@code boolean}.</p>
835      *
836      * <pre>
837      *   BooleanUtils.toBooleanObject("true", "true", "false", "null")   = Boolean.TRUE
838      *   BooleanUtils.toBooleanObject(null, null, "false", "null")       = Boolean.TRUE
839      *   BooleanUtils.toBooleanObject(null, null, null, "null")          = Boolean.TRUE
840      *   BooleanUtils.toBooleanObject(null, null, null, null)            = Boolean.TRUE
841      *   BooleanUtils.toBooleanObject("false", "true", "false", "null")  = Boolean.FALSE
842      *   BooleanUtils.toBooleanObject("false", "true", "false", "false") = Boolean.FALSE
843      *   BooleanUtils.toBooleanObject(null, "true", null, "false")       = Boolean.FALSE
844      *   BooleanUtils.toBooleanObject(null, "true", null, null)          = Boolean.FALSE
845      *   BooleanUtils.toBooleanObject("null", "true", "false", "null")   = null
846      * </pre>
847      *
848      * @param str  the String to check
849      * @param trueString  the String to match for {@code true} (case-sensitive), may be {@code null}
850      * @param falseString  the String to match for {@code false} (case-sensitive), may be {@code null}
851      * @param nullString  the String to match for {@code null} (case-sensitive), may be {@code null}
852      * @return the Boolean value of the string, {@code null} if either the String matches {@code nullString}
853      *  or if {@code null} input and {@code nullString} is {@code null}
854      * @throws IllegalArgumentException if the String doesn't match
855      */
856     public static Boolean toBooleanObject(final String str, final String trueString, final String falseString, final String nullString) {
857         if (str == null) {
858             if (trueString == null) {
859                 return Boolean.TRUE;
860             }
861             if (falseString == null) {
862                 return Boolean.FALSE;
863             }
864             if (nullString == null) {
865                 return null;
866             }
867         } else if (str.equals(trueString)) {
868             return Boolean.TRUE;
869         } else if (str.equals(falseString)) {
870             return Boolean.FALSE;
871         } else if (str.equals(nullString)) {
872             return null;
873         }
874         // no match
875         throw new IllegalArgumentException("The String did not match any specified value");
876     }
877 
878     /**
879      * Converts a boolean to an int using the convention that
880      * {@code true} is {@code 1} and {@code false} is {@code 0}.
881      *
882      * <pre>
883      *   BooleanUtils.toInteger(true)  = 1
884      *   BooleanUtils.toInteger(false) = 0
885      * </pre>
886      *
887      * @param bool  the boolean to convert
888      * @return one if {@code true}, zero if {@code false}
889      */
890     public static int toInteger(final boolean bool) {
891         return bool ? 1 : 0;
892     }
893 
894     /**
895      * Converts a boolean to an int specifying the conversion values.
896      *
897      * <pre>
898      *   BooleanUtils.toInteger(true, 1, 0)  = 1
899      *   BooleanUtils.toInteger(false, 1, 0) = 0
900      * </pre>
901      *
902      * @param bool  the to convert
903      * @param trueValue  the value to return if {@code true}
904      * @param falseValue  the value to return if {@code false}
905      * @return the appropriate value
906      */
907     public static int toInteger(final boolean bool, final int trueValue, final int falseValue) {
908         return bool ? trueValue : falseValue;
909     }
910 
911     /**
912      * Converts a Boolean to an int specifying the conversion values.
913      *
914      * <pre>
915      *   BooleanUtils.toInteger(Boolean.TRUE, 1, 0, 2)  = 1
916      *   BooleanUtils.toInteger(Boolean.FALSE, 1, 0, 2) = 0
917      *   BooleanUtils.toInteger(null, 1, 0, 2)          = 2
918      * </pre>
919      *
920      * @param bool  the Boolean to convert
921      * @param trueValue  the value to return if {@code true}
922      * @param falseValue  the value to return if {@code false}
923      * @param nullValue  the value to return if {@code null}
924      * @return the appropriate value
925      */
926     public static int toInteger(final Boolean bool, final int trueValue, final int falseValue, final int nullValue) {
927         if (bool == null) {
928             return nullValue;
929         }
930         return bool.booleanValue() ? trueValue : falseValue;
931     }
932 
933     /**
934      * Converts a boolean to an Integer using the convention that
935      * {@code true} is {@code 1} and {@code false} is {@code 0}.
936      *
937      * <pre>
938      *   BooleanUtils.toIntegerObject(true)  = Integer.valueOf(1)
939      *   BooleanUtils.toIntegerObject(false) = Integer.valueOf(0)
940      * </pre>
941      *
942      * @param bool  the boolean to convert
943      * @return one if {@code true}, zero if {@code false}
944      */
945     public static Integer toIntegerObject(final boolean bool) {
946         return bool ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO;
947     }
948 
949     /**
950      * Converts a boolean to an Integer specifying the conversion values.
951      *
952      * <pre>
953      *   BooleanUtils.toIntegerObject(true, Integer.valueOf(1), Integer.valueOf(0))  = Integer.valueOf(1)
954      *   BooleanUtils.toIntegerObject(false, Integer.valueOf(1), Integer.valueOf(0)) = Integer.valueOf(0)
955      * </pre>
956      *
957      * @param bool  the to convert
958      * @param trueValue  the value to return if {@code true}, may be {@code null}
959      * @param falseValue  the value to return if {@code false}, may be {@code null}
960      * @return the appropriate value
961      */
962     public static Integer toIntegerObject(final boolean bool, final Integer trueValue, final Integer falseValue) {
963         return bool ? trueValue : falseValue;
964     }
965 
966     /**
967      * Converts a Boolean to an Integer using the convention that
968      * {@code zero} is {@code false}.
969      *
970      * <p>{@code null} will be converted to {@code null}.</p>
971      *
972      * <pre>
973      *   BooleanUtils.toIntegerObject(Boolean.TRUE)  = Integer.valueOf(1)
974      *   BooleanUtils.toIntegerObject(Boolean.FALSE) = Integer.valueOf(0)
975      * </pre>
976      *
977      * @param bool  the Boolean to convert
978      * @return one if Boolean.TRUE, zero if Boolean.FALSE, {@code null} if {@code null}
979      */
980     public static Integer toIntegerObject(final Boolean bool) {
981         if (bool == null) {
982             return null;
983         }
984         return bool.booleanValue() ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO;
985     }
986 
987     /**
988      * Converts a Boolean to an Integer specifying the conversion values.
989      *
990      * <pre>
991      *   BooleanUtils.toIntegerObject(Boolean.TRUE, Integer.valueOf(1), Integer.valueOf(0), Integer.valueOf(2))  = Integer.valueOf(1)
992      *   BooleanUtils.toIntegerObject(Boolean.FALSE, Integer.valueOf(1), Integer.valueOf(0), Integer.valueOf(2)) = Integer.valueOf(0)
993      *   BooleanUtils.toIntegerObject(null, Integer.valueOf(1), Integer.valueOf(0), Integer.valueOf(2))          = Integer.valueOf(2)
994      * </pre>
995      *
996      * @param bool  the Boolean to convert
997      * @param trueValue  the value to return if {@code true}, may be {@code null}
998      * @param falseValue  the value to return if {@code false}, may be {@code null}
999      * @param nullValue  the value to return if {@code null}, may be {@code null}
1000      * @return the appropriate value
1001      */
1002     public static Integer toIntegerObject(final Boolean bool, final Integer trueValue, final Integer falseValue, final Integer nullValue) {
1003         if (bool == null) {
1004             return nullValue;
1005         }
1006         return bool.booleanValue() ? trueValue : falseValue;
1007     }
1008 
1009     /**
1010      * Converts a boolean to a String returning one of the input Strings.
1011      *
1012      * <pre>
1013      *   BooleanUtils.toString(true, "true", "false")   = "true"
1014      *   BooleanUtils.toString(false, "true", "false")  = "false"
1015      * </pre>
1016      *
1017      * @param bool  the Boolean to check
1018      * @param trueString  the String to return if {@code true}, may be {@code null}
1019      * @param falseString  the String to return if {@code false}, may be {@code null}
1020      * @return one of the two input Strings
1021      */
1022     public static String toString(final boolean bool, final String trueString, final String falseString) {
1023         return bool ? trueString : falseString;
1024     }
1025 
1026     /**
1027      * Converts a Boolean to a String returning one of the input Strings.
1028      *
1029      * <pre>
1030      *   BooleanUtils.toString(Boolean.TRUE, "true", "false", null)   = "true"
1031      *   BooleanUtils.toString(Boolean.FALSE, "true", "false", null)  = "false"
1032      *   BooleanUtils.toString(null, "true", "false", null)           = null;
1033      * </pre>
1034      *
1035      * @param bool  the Boolean to check
1036      * @param trueString  the String to return if {@code true}, may be {@code null}
1037      * @param falseString  the String to return if {@code false}, may be {@code null}
1038      * @param nullString  the String to return if {@code null}, may be {@code null}
1039      * @return one of the three input Strings
1040      */
1041     public static String toString(final Boolean bool, final String trueString, final String falseString, final String nullString) {
1042         if (bool == null) {
1043             return nullString;
1044         }
1045         return bool.booleanValue() ? trueString : falseString;
1046     }
1047 
1048     /**
1049      * Converts a boolean to a String returning {@code 'on'}
1050      * or {@code 'off'}.
1051      *
1052      * <pre>
1053      *   BooleanUtils.toStringOnOff(true)   = "on"
1054      *   BooleanUtils.toStringOnOff(false)  = "off"
1055      * </pre>
1056      *
1057      * @param bool  the Boolean to check
1058      * @return {@code 'on'}, {@code 'off'}, or {@code null}
1059      */
1060     public static String toStringOnOff(final boolean bool) {
1061         return toString(bool, ON, OFF);
1062     }
1063 
1064     /**
1065      * Converts a Boolean to a String returning {@code 'on'},
1066      * {@code 'off'}, or {@code null}.
1067      *
1068      * <pre>
1069      *   BooleanUtils.toStringOnOff(Boolean.TRUE)  = "on"
1070      *   BooleanUtils.toStringOnOff(Boolean.FALSE) = "off"
1071      *   BooleanUtils.toStringOnOff(null)          = null;
1072      * </pre>
1073      *
1074      * @param bool  the Boolean to check
1075      * @return {@code 'on'}, {@code 'off'}, or {@code null}
1076      */
1077     public static String toStringOnOff(final Boolean bool) {
1078         return toString(bool, ON, OFF, null);
1079     }
1080 
1081     /**
1082      * Converts a boolean to a String returning {@code 'true'}
1083      * or {@code 'false'}.
1084      *
1085      * <pre>
1086      *   BooleanUtils.toStringTrueFalse(true)   = "true"
1087      *   BooleanUtils.toStringTrueFalse(false)  = "false"
1088      * </pre>
1089      *
1090      * @param bool  the Boolean to check
1091      * @return {@code 'true'}, {@code 'false'}, or {@code null}
1092      */
1093     public static String toStringTrueFalse(final boolean bool) {
1094         return toString(bool, TRUE, FALSE);
1095     }
1096 
1097     /**
1098      * Converts a Boolean to a String returning {@code 'true'},
1099      * {@code 'false'}, or {@code null}.
1100      *
1101      * <pre>
1102      *   BooleanUtils.toStringTrueFalse(Boolean.TRUE)  = "true"
1103      *   BooleanUtils.toStringTrueFalse(Boolean.FALSE) = "false"
1104      *   BooleanUtils.toStringTrueFalse(null)          = null;
1105      * </pre>
1106      *
1107      * @param bool  the Boolean to check
1108      * @return {@code 'true'}, {@code 'false'}, or {@code null}
1109      */
1110     public static String toStringTrueFalse(final Boolean bool) {
1111         return toString(bool, TRUE, FALSE, null);
1112     }
1113 
1114     /**
1115      * Converts a boolean to a String returning {@code 'yes'}
1116      * or {@code 'no'}.
1117      *
1118      * <pre>
1119      *   BooleanUtils.toStringYesNo(true)   = "yes"
1120      *   BooleanUtils.toStringYesNo(false)  = "no"
1121      * </pre>
1122      *
1123      * @param bool  the Boolean to check
1124      * @return {@code 'yes'}, {@code 'no'}, or {@code null}
1125      */
1126     public static String toStringYesNo(final boolean bool) {
1127         return toString(bool, YES, NO);
1128     }
1129 
1130     /**
1131      * Converts a Boolean to a String returning {@code 'yes'},
1132      * {@code 'no'}, or {@code null}.
1133      *
1134      * <pre>
1135      *   BooleanUtils.toStringYesNo(Boolean.TRUE)  = "yes"
1136      *   BooleanUtils.toStringYesNo(Boolean.FALSE) = "no"
1137      *   BooleanUtils.toStringYesNo(null)          = null;
1138      * </pre>
1139      *
1140      * @param bool  the Boolean to check
1141      * @return {@code 'yes'}, {@code 'no'}, or {@code null}
1142      */
1143     public static String toStringYesNo(final Boolean bool) {
1144         return toString(bool, YES, NO, null);
1145     }
1146 
1147     /**
1148      * Returns an unmodifiable list of Booleans {@code [false, true]}.
1149      *
1150      * @return an unmodifiable list of Booleans {@code [false, true]}.
1151      * @since 3.13.0
1152      */
1153     public static List<Boolean> values() {
1154         return BOOLEAN_LIST;
1155     }
1156 
1157     /**
1158      * Performs an xor on a set of booleans.
1159      * <p>
1160      *   This behaves like an XOR gate;
1161      *   it returns true if the number of true values is odd,
1162      *   and false if the number of true values is zero or even.
1163      * </p>
1164      *
1165      * <pre>
1166      *   BooleanUtils.xor(true, true)             = false
1167      *   BooleanUtils.xor(false, false)           = false
1168      *   BooleanUtils.xor(true, false)            = true
1169      *   BooleanUtils.xor(true, false, false)     = true
1170      *   BooleanUtils.xor(true, true, true)       = true
1171      *   BooleanUtils.xor(true, true, true, true) = false
1172      * </pre>
1173      *
1174      * @param array  an array of {@code boolean}s
1175      * @return true if the number of true values in the array is odd; otherwise returns false.
1176      * @throws NullPointerException if {@code array} is {@code null}
1177      * @throws IllegalArgumentException if {@code array} is empty.
1178      */
1179     public static boolean xor(final boolean... array) {
1180         ObjectUtils.requireNonEmpty(array, "array");
1181         // false if the neutral element of the xor operator
1182         boolean result = false;
1183         for (final boolean element : array) {
1184             result ^= element;
1185         }
1186 
1187         return result;
1188     }
1189 
1190     /**
1191      * Performs an xor on an array of Booleans.
1192      * <pre>
1193      *   BooleanUtils.xor(Boolean.TRUE, Boolean.TRUE)                 = Boolean.FALSE
1194      *   BooleanUtils.xor(Boolean.FALSE, Boolean.FALSE)               = Boolean.FALSE
1195      *   BooleanUtils.xor(Boolean.TRUE, Boolean.FALSE)                = Boolean.TRUE
1196      *   BooleanUtils.xor(Boolean.TRUE, Boolean.FALSE, Boolean.FALSE) = Boolean.TRUE
1197      *   BooleanUtils.xor(Boolean.FALSE, null)                        = Boolean.FALSE
1198      *   BooleanUtils.xor(Boolean.TRUE, null)                         = Boolean.TRUE
1199      * </pre>
1200      * <p>
1201      * Null array elements map to false, like {@code Boolean.parseBoolean(null)} and its callers return false.
1202      * </p>
1203      *
1204      * @param array  an array of {@link Boolean}s
1205      * @return the result of the xor operations
1206      * @throws NullPointerException if {@code array} is {@code null}
1207      * @throws IllegalArgumentException if {@code array} is empty.
1208      */
1209     public static Boolean xor(final Boolean... array) {
1210         ObjectUtils.requireNonEmpty(array, "array");
1211         return xor(ArrayUtils.toPrimitive(array)) ? Boolean.TRUE : Boolean.FALSE;
1212     }
1213 
1214     /**
1215      * {@link BooleanUtils} instances should NOT be constructed in standard programming.
1216      * Instead, the class should be used as {@code BooleanUtils.negate(true);}.
1217      *
1218      * <p>This constructor is public to permit tools that require a JavaBean instance
1219      * to operate.</p>
1220      *
1221      * @deprecated TODO Make private in 4.0.
1222      */
1223     @Deprecated
1224     public BooleanUtils() {
1225         // empty
1226     }
1227 
1228 }