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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.security.SecureRandom;
20  import java.security.Security;
21  import java.util.Random;
22  import java.util.concurrent.ThreadLocalRandom;
23  import java.util.function.Supplier;
24  
25  /**
26   * Generates random {@link String}s.
27   * <p>
28   * Use {@link #secure()} to get the singleton instance based on {@link SecureRandom#SecureRandom()} which uses a secure random number generator implementing the
29   * default random number algorithm.
30   * </p>
31   * <p>
32   * Use {@link #secureStrong()} to get the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an instance that was selected by using
33   * the algorithms/providers specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
34   * </p>
35   * <p>
36   * Use {@link #insecure()} to get the singleton instance based on {@link ThreadLocalRandom#current()} <strong>which is not cryptographically secure</strong>. In addition,
37   * instances do not use a cryptographically random seed unless the {@linkplain System#getProperty system property} {@code java.util.secureRandomSeed} is set to
38   * {@code true}.
39   * </p>
40   * <p>
41   * Starting in version 3.17.0, the method {@link #secure()} uses {@link SecureRandom#SecureRandom()} instead of {@link SecureRandom#getInstanceStrong()}, and
42   * adds {@link #secureStrong()}.
43   * </p>
44   * <p>
45   * Starting in version 3.16.0, this class uses {@link #secure()} for static methods and adds {@link #insecure()}.
46   * </p>
47   * <p>
48   * Starting in version 3.15.0, this class uses {@link SecureRandom#getInstanceStrong()} for static methods.
49   * </p>
50   * <p>
51   * Before version 3.15.0, this class used {@link ThreadLocalRandom#current()} for static methods, which is not cryptographically secure.
52   * </p>
53   * <p>
54   * RandomStringUtils is intended for simple use cases. For more advanced use cases consider using Apache Commons Text's
55   * <a href= "https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/RandomStringGenerator.html"> RandomStringGenerator</a>
56   * instead.
57   * </p>
58   * <p>
59   * The Apache Commons project provides <a href="https://commons.apache.org/proper/commons-rng/">Commons RNG</a> dedicated to pseudo-random number generation,
60   * that may be a better choice for applications with more stringent requirements (performance and/or correctness).
61   * </p>
62   * <p>
63   * Note that <em>private high surrogate</em> characters are ignored. These are Unicode characters that fall between the values 56192 (db80) and 56319 (dbff) as
64   * we don't know how to handle them. High and low surrogates are correctly dealt with - that is if a high surrogate is randomly chosen, 55296 (d800) to 56191
65   * (db7f) then it is followed by a low surrogate. If a low surrogate is chosen, 56320 (dc00) to 57343 (dfff) then it is placed after a randomly chosen high
66   * surrogate.
67   * </p>
68   * <p>
69   * #ThreadSafe#
70   * </p>
71   *
72   * @see #secure()
73   * @see #secureStrong()
74   * @see #insecure()
75   * @see SecureRandom#SecureRandom()
76   * @see SecureRandom#getInstanceStrong()
77   * @see ThreadLocalRandom#current()
78   * @see RandomUtils
79   * @since 1.0
80   */
81  public class RandomStringUtils {
82  
83      private static final Supplier<RandomUtils> SECURE_SUPPLIER = RandomUtils::secure;
84  
85      private static RandomStringUtils INSECURE = new RandomStringUtils(RandomUtils::insecure);
86  
87      private static RandomStringUtils SECURE = new RandomStringUtils(SECURE_SUPPLIER);
88  
89      private static RandomStringUtils SECURE_STRONG = new RandomStringUtils(RandomUtils::secureStrong);
90  
91      private static final char[] ALPHANUMERICAL_CHARS = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
92              'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
93              'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1',
94              '2', '3', '4', '5', '6', '7', '8', '9' };
95  
96      private static final int ASCII_0 = '0';
97      private static final int ASCII_9 = '9';
98      private static final int ASCII_A = 'A';
99      private static final int ASCII_z = 'z';
100 
101     private static final int CACHE_PADDING_BITS = 3;
102     private static final int BITS_TO_BYTES_DIVISOR = 5;
103     private static final int BASE_CACHE_SIZE_PADDING = 10;
104 
105     /**
106      * Gets the singleton instance based on {@link ThreadLocalRandom#current()}; <b>which is not cryptographically
107      * secure</b>; use {@link #secure()} to use an algorithms/providers specified in the
108      * {@code securerandom.strongAlgorithms} {@link Security} property.
109      * <p>
110      * The method {@link ThreadLocalRandom#current()} is called on-demand.
111      * </p>
112      *
113      * @return the singleton instance based on {@link ThreadLocalRandom#current()}.
114      * @see ThreadLocalRandom#current()
115      * @see #secure()
116      * @since 3.16.0
117      */
118     public static RandomStringUtils insecure() {
119         return INSECURE;
120     }
121 
122     /**
123      * Creates a random string whose length is the number of characters specified.
124      *
125      * <p>
126      * Characters will be chosen from the set of all characters.
127      * </p>
128      *
129      * @param count the length of random string to create.
130      * @return the random string.
131      * @throws IllegalArgumentException if {@code count} &lt; 0.
132      * @deprecated Use {@link #next(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
133      */
134     @Deprecated
135     public static String random(final int count) {
136         return secure().next(count);
137     }
138 
139     /**
140      * Creates a random string whose length is the number of characters specified.
141      *
142      * <p>
143      * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
144      * </p>
145      *
146      * @param count   the length of random string to create.
147      * @param letters if {@code true}, generated string may include alphabetic characters.
148      * @param numbers if {@code true}, generated string may include numeric characters.
149      * @return the random string.
150      * @throws IllegalArgumentException if {@code count} &lt; 0.
151      * @deprecated Use {@link #next(int, boolean, boolean)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
152      */
153     @Deprecated
154     public static String random(final int count, final boolean letters, final boolean numbers) {
155         return secure().next(count, letters, numbers);
156     }
157 
158     /**
159      * Creates a random string whose length is the number of characters specified.
160      *
161      * <p>
162      * Characters will be chosen from the set of characters specified.
163      * </p>
164      *
165      * @param count the length of random string to create.
166      * @param chars the character array containing the set of characters to use, may be null.
167      * @return the random string.
168      * @throws IllegalArgumentException if {@code count} &lt; 0.
169      * @deprecated Use {@link #next(int, char...)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
170      */
171     @Deprecated
172     public static String random(final int count, final char... chars) {
173         return secure().next(count, chars);
174     }
175 
176     /**
177      * Creates a random string whose length is the number of characters specified.
178      *
179      * <p>
180      * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
181      * </p>
182      *
183      * @param count   the length of random string to create.
184      * @param start   the position in set of chars to start at.
185      * @param end     the position in set of chars to end before.
186      * @param letters if {@code true}, generated string may include alphabetic characters.
187      * @param numbers if {@code true}, generated string may include numeric characters.
188      * @return the random string.
189      * @throws IllegalArgumentException if {@code count} &lt; 0.
190      * @deprecated Use {@link #next(int, int, int, boolean, boolean)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
191      */
192     @Deprecated
193     public static String random(final int count, final int start, final int end, final boolean letters,
194             final boolean numbers) {
195         return secure().next(count, start, end, letters, numbers);
196     }
197 
198     /**
199      * Creates a random string based on a variety of options, using default source of randomness.
200      *
201      * <p>
202      * This method has exactly the same semantics as {@link #random(int,int,int,boolean,boolean,char[],Random)}, but
203      * instead of using an externally supplied source of randomness, it uses the internal static {@link Random}
204      * instance.
205      * </p>
206      *
207      * @param count   the length of random string to create.
208      * @param start   the position in set of chars to start at.
209      * @param end     the position in set of chars to end before.
210      * @param letters if {@code true}, generated string may include alphabetic characters.
211      * @param numbers if {@code true}, generated string may include numeric characters.
212      * @param chars   the set of chars to choose randoms from. If {@code null}, then it will use the set of all chars.
213      * @return the random string.
214      * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
215      * @throws IllegalArgumentException       if {@code count} &lt; 0.
216      * @deprecated Use {@link #next(int, int, int, boolean, boolean, char...)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
217      */
218     @Deprecated
219     public static String random(final int count, final int start, final int end, final boolean letters,
220             final boolean numbers, final char... chars) {
221         return secure().next(count, start, end, letters, numbers, chars);
222     }
223 
224     /**
225      * Creates a random string based on a variety of options, using supplied source of randomness.
226      *
227      * <p>
228      * If start and end are both {@code 0}, start and end are set to {@code ' '} and {@code 'z'}, the ASCII printable
229      * characters, will be used, unless letters and numbers are both {@code false}, in which case, start and end are set
230      * to {@code 0} and {@link Character#MAX_CODE_POINT}.
231      *
232      * <p>
233      * If set is not {@code null}, characters between start and end are chosen.
234      * </p>
235      *
236      * <p>
237      * This method accepts a user-supplied {@link Random} instance to use as a source of randomness. By seeding a single
238      * {@link Random} instance with a fixed seed and using it for each call, the same random sequence of strings can be
239      * generated repeatedly and predictably.
240      * </p>
241      *
242      * @param count   the length of random string to create.
243      * @param start   the position in set of chars to start at (inclusive).
244      * @param end     the position in set of chars to end before (exclusive).
245      * @param letters if {@code true}, generated string may include alphabetic characters.
246      * @param numbers if {@code true}, generated string may include numeric characters.
247      * @param chars   the set of chars to choose randoms from, must not be empty. If {@code null}, then it will use the
248      *                set of all chars.
249      * @param random  a source of randomness.
250      * @return the random string.
251      * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
252      * @throws IllegalArgumentException       if {@code count} &lt; 0 or the provided chars array is empty.
253      * @since 2.0
254      */
255     public static String random(int count, int start, int end, final boolean letters, final boolean numbers,
256             final char[] chars, final Random random) {
257         if (count == 0) {
258             return StringUtils.EMPTY;
259         }
260         if (count < 0) {
261             throw new IllegalArgumentException("Requested random string length " + count + " is less than 0.");
262         }
263         if (chars != null && chars.length == 0) {
264             throw new IllegalArgumentException("The chars array must not be empty");
265         }
266 
267         if (start == 0 && end == 0) {
268             if (chars != null) {
269                 end = chars.length;
270             } else if (!letters && !numbers) {
271                 end = Character.MAX_CODE_POINT;
272             } else {
273                 end = 'z' + 1;
274                 start = ' ';
275             }
276         } else if (end <= start) {
277             throw new IllegalArgumentException(
278                     "Parameter end (" + end + ") must be greater than start (" + start + ")");
279         } else if (start < 0 || end < 0) {
280             throw new IllegalArgumentException("Character positions MUST be >= 0");
281         }
282 
283         if (end > Character.MAX_CODE_POINT) {
284             // Technically, it should be `Character.MAX_CODE_POINT+1` as `end` is excluded
285             // But the character `Character.MAX_CODE_POINT` is private use, so it would anyway be excluded
286             end = Character.MAX_CODE_POINT;
287         }
288 
289         // Optimizations and tests when chars == null and using ASCII characters (end <= 0x7f)
290         if (chars == null && end <= 0x7f) {
291             // Optimize generation of full alphanumerical characters
292             // Normally, we would need to pick a 7-bit integer, since gap = 'z' - '0' + 1 = 75 > 64
293             // In turn, this would make us reject the sampling with probability 1 - 62 / 2^7 > 1 / 2
294             // Instead we can pick directly from the right set of 62 characters, which requires
295             // picking a 6-bit integer and only rejecting with probability 2 / 64 = 1 / 32
296             if (letters && numbers && start <= ASCII_0 && end >= ASCII_z + 1) {
297                 return random(count, 0, 0, false, false, ALPHANUMERICAL_CHARS, random);
298             }
299 
300             if (numbers && end <= ASCII_0 || letters && end <= ASCII_A) {
301                 throw new IllegalArgumentException(
302                         "Parameter end (" + end + ") must be greater then (" + ASCII_0 + ") for generating digits "
303                                 + "or greater then (" + ASCII_A + ") for generating letters.");
304             }
305 
306             // Optimize start and end when filtering by letters and/or numbers:
307             // The range provided may be too large since we filter anyway afterward.
308             // Note the use of Math.min/max (as opposed to setting start to '0' for example),
309             // since it is possible the range start/end excludes some of the letters/numbers,
310             // e.g., it is possible that start already is '1' when numbers = true, and start
311             // needs to stay equal to '1' in that case.
312             // Note that because of the above test, we will always have start < end
313             // even after this optimization.
314             if (letters && numbers) {
315                 start = Math.max(ASCII_0, start);
316                 end = Math.min(ASCII_z + 1, end);
317             } else if (numbers) {
318                 // just numbers, no letters
319                 start = Math.max(ASCII_0, start);
320                 end = Math.min(ASCII_9 + 1, end);
321             } else if (letters) {
322                 // just letters, no numbers
323                 start = Math.max(ASCII_A, start);
324                 end = Math.min(ASCII_z + 1, end);
325             }
326         }
327 
328         final StringBuilder builder = new StringBuilder(count);
329         final int gap = end - start;
330         final int gapBits = Integer.SIZE - Integer.numberOfLeadingZeros(gap);
331         // The size of the cache we use is an heuristic:
332         // about twice the number of bytes required if no rejection
333         // Ideally the cache size depends on multiple factor, including the cost of generating x bytes
334         // of randomness as well as the probability of rejection. It is however not easy to know
335         // those values programmatically for the general case.
336         // Calculate cache size:
337         // 1. Multiply count by bits needed per character (gapBits)
338         // 2. Add padding bits (3) to handle partial bytes
339         // 3. Divide by 5 to convert to bytes (normally this would be by 8, dividing by 5 allows for about 60% extra space)
340         // 4. Add base padding (10) to handle small counts efficiently
341         // 5. Ensure we don't exceed Integer.MAX_VALUE / 5 + 10 to provide a good balance between overflow prevention and
342         //    making the cache extremely large
343         final long desiredCacheSize = ((long) count * gapBits + CACHE_PADDING_BITS) / BITS_TO_BYTES_DIVISOR + BASE_CACHE_SIZE_PADDING;
344         final int cacheSize = (int) Math.min(desiredCacheSize, Integer.MAX_VALUE / BITS_TO_BYTES_DIVISOR + BASE_CACHE_SIZE_PADDING);
345         final CachedRandomBits arb = new CachedRandomBits(cacheSize, random);
346 
347         while (count-- != 0) {
348             // Generate a random value between start (included) and end (excluded)
349             final int randomValue = arb.nextBits(gapBits) + start;
350             // Rejection sampling if value too large
351             if (randomValue >= end) {
352                 count++;
353                 continue;
354             }
355 
356             final int codePoint;
357             if (chars == null) {
358                 codePoint = randomValue;
359 
360                 switch (Character.getType(codePoint)) {
361                 case Character.UNASSIGNED:
362                 case Character.PRIVATE_USE:
363                 case Character.SURROGATE:
364                     count++;
365                     continue;
366                 }
367 
368             } else {
369                 codePoint = chars[randomValue];
370             }
371 
372             final int numberOfChars = Character.charCount(codePoint);
373             if (count == 0 && numberOfChars > 1) {
374                 count++;
375                 continue;
376             }
377 
378             if (letters && Character.isLetter(codePoint) || numbers && Character.isDigit(codePoint)
379                     || !letters && !numbers) {
380                 builder.appendCodePoint(codePoint);
381 
382                 if (numberOfChars == 2) {
383                     count--;
384                 }
385 
386             } else {
387                 count++;
388             }
389         }
390         return builder.toString();
391     }
392 
393     /**
394      * Creates a random string whose length is the number of characters specified.
395      *
396      * <p>
397      * Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set
398      * of all characters is used.
399      * </p>
400      *
401      * @param count the length of random string to create.
402      * @param chars the String containing the set of characters to use, may be null, but must not be empty.
403      * @return the random string.
404      * @throws IllegalArgumentException if {@code count} &lt; 0 or the string is empty.
405      * @deprecated Use {@link #next(int, String)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
406      */
407     @Deprecated
408     public static String random(final int count, final String chars) {
409         return secure().next(count, chars);
410     }
411 
412     /**
413      * Creates a random string whose length is the number of characters specified.
414      *
415      * <p>
416      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
417      * </p>
418      *
419      * @param count the length of random string to create.
420      * @return the random string.
421      * @throws IllegalArgumentException if {@code count} &lt; 0.
422      * @deprecated Use {@link #nextAlphabetic(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
423      */
424     @Deprecated
425     public static String randomAlphabetic(final int count) {
426         return secure().nextAlphabetic(count);
427     }
428 
429     /**
430      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
431      *
432      * <p>
433      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
434      * </p>
435      *
436      * @param minLengthInclusive the inclusive minimum length of the string to generate.
437      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
438      * @return the random string.
439      * @since 3.5
440      * @deprecated Use {@link #nextAlphabetic(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
441      */
442     @Deprecated
443     public static String randomAlphabetic(final int minLengthInclusive, final int maxLengthExclusive) {
444         return secure().nextAlphabetic(minLengthInclusive, maxLengthExclusive);
445     }
446 
447     /**
448      * Creates a random string whose length is the number of characters specified.
449      *
450      * <p>
451      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
452      * </p>
453      *
454      * @param count the length of random string to create.
455      * @return the random string.
456      * @throws IllegalArgumentException if {@code count} &lt; 0.
457      * @deprecated Use {@link #nextAlphanumeric(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
458      */
459     @Deprecated
460     public static String randomAlphanumeric(final int count) {
461         return secure().nextAlphanumeric(count);
462     }
463 
464     /**
465      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
466      *
467      * <p>
468      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
469      * </p>
470      *
471      * @param minLengthInclusive the inclusive minimum length of the string to generate.
472      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
473      * @return the random string.
474      * @since 3.5
475      * @deprecated Use {@link #nextAlphanumeric(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
476      */
477     @Deprecated
478     public static String randomAlphanumeric(final int minLengthInclusive, final int maxLengthExclusive) {
479         return secure().nextAlphanumeric(minLengthInclusive, maxLengthExclusive);
480     }
481 
482     /**
483      * Creates a random string whose length is the number of characters specified.
484      *
485      * <p>
486      * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
487      * (inclusive).
488      * </p>
489      *
490      * @param count the length of random string to create.
491      * @return the random string.
492      * @throws IllegalArgumentException if {@code count} &lt; 0.
493      * @deprecated Use {@link #nextAscii(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
494      */
495     @Deprecated
496     public static String randomAscii(final int count) {
497         return secure().nextAscii(count);
498     }
499 
500     /**
501      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
502      *
503      * <p>
504      * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
505      * (inclusive).
506      * </p>
507      *
508      * @param minLengthInclusive the inclusive minimum length of the string to generate.
509      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
510      * @return the random string.
511      * @since 3.5
512      * @deprecated Use {@link #nextAscii(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
513      */
514     @Deprecated
515     public static String randomAscii(final int minLengthInclusive, final int maxLengthExclusive) {
516         return secure().nextAscii(minLengthInclusive, maxLengthExclusive);
517     }
518 
519     /**
520      * Creates a random string whose length is the number of characters specified.
521      *
522      * <p>
523      * Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character
524      * class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
525      * </p>
526      *
527      * @param count the length of random string to create.
528      * @return the random string.
529      * @throws IllegalArgumentException if {@code count} &lt; 0.
530      * @since 3.5
531      * @deprecated Use {@link #nextGraph(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
532      */
533     @Deprecated
534     public static String randomGraph(final int count) {
535         return secure().nextGraph(count);
536     }
537 
538     /**
539      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
540      *
541      * <p>
542      * Characters will be chosen from the set of \p{Graph} characters.
543      * </p>
544      *
545      * @param minLengthInclusive the inclusive minimum length of the string to generate.
546      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
547      * @return the random string.
548      * @since 3.5
549      * @deprecated Use {@link #nextGraph(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
550      */
551     @Deprecated
552     public static String randomGraph(final int minLengthInclusive, final int maxLengthExclusive) {
553         return secure().nextGraph(minLengthInclusive, maxLengthExclusive);
554     }
555 
556     /**
557      * Creates a random string whose length is the number of characters specified.
558      *
559      * <p>
560      * Characters will be chosen from the set of numeric characters.
561      * </p>
562      *
563      * @param count the length of random string to create.
564      * @return the random string.
565      * @throws IllegalArgumentException if {@code count} &lt; 0.
566      * @deprecated Use {@link #nextNumeric(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
567      */
568     @Deprecated
569     public static String randomNumeric(final int count) {
570         return secure().nextNumeric(count);
571     }
572 
573     /**
574      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
575      *
576      * <p>
577      * Characters will be chosen from the set of \p{Digit} characters.
578      * </p>
579      *
580      * @param minLengthInclusive the inclusive minimum length of the string to generate.
581      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
582      * @return the random string.
583      * @since 3.5
584      * @deprecated Use {@link #nextNumeric(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
585      */
586     @Deprecated
587     public static String randomNumeric(final int minLengthInclusive, final int maxLengthExclusive) {
588         return secure().nextNumeric(minLengthInclusive, maxLengthExclusive);
589     }
590 
591     /**
592      * Creates a random string whose length is the number of characters specified.
593      *
594      * <p>
595      * Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character
596      * class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
597      * </p>
598      *
599      * @param count the length of random string to create.
600      * @return the random string.
601      * @throws IllegalArgumentException if {@code count} &lt; 0.
602      * @since 3.5
603      * @deprecated Use {@link #randomPrint(int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
604      */
605     @Deprecated
606     public static String randomPrint(final int count) {
607         return secure().nextPrint(count);
608     }
609 
610     /**
611      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
612      *
613      * <p>
614      * Characters will be chosen from the set of \p{Print} characters.
615      * </p>
616      *
617      * @param minLengthInclusive the inclusive minimum length of the string to generate.
618      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
619      * @return the random string.
620      * @since 3.5
621      * @deprecated Use {@link #randomPrint(int, int)} from {@link #secure()}, {@link #secureStrong()}, or {@link #insecure()}.
622      */
623     @Deprecated
624     public static String randomPrint(final int minLengthInclusive, final int maxLengthExclusive) {
625         return secure().nextPrint(minLengthInclusive, maxLengthExclusive);
626     }
627 
628     /**
629      * Gets the singleton instance based on {@link SecureRandom#SecureRandom()} which uses a secure random number generator (RNG) implementing the default
630      * random number algorithm.
631      * <p>
632      * The method {@link SecureRandom#SecureRandom()} is called on-demand.
633      * </p>
634      *
635      * @return the singleton instance based on {@link SecureRandom#SecureRandom()}.
636      * @see SecureRandom#SecureRandom()
637      * @since 3.16.0
638      */
639     public static RandomStringUtils secure() {
640         return SECURE;
641     }
642 
643     /**
644      * Gets the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an algorithms/providers
645      * specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
646      * <p>
647      * The method {@link SecureRandom#getInstanceStrong()} is called on-demand.
648      * </p>
649      *
650      * @return the singleton instance based on {@link SecureRandom#getInstanceStrong()}.
651      * @see SecureRandom#getInstanceStrong()
652      * @since 3.17.0
653      */
654     public static RandomStringUtils secureStrong() {
655         return SECURE_STRONG;
656     }
657 
658     private final Supplier<RandomUtils> random;
659 
660     /**
661      * {@link RandomStringUtils} instances should NOT be constructed in standard programming. Instead, the class should
662      * be used as {@code RandomStringUtils.random(5);}.
663      *
664      * <p>
665      * This constructor is public to permit tools that require a JavaBean instance to operate.
666      * </p>
667      *
668      * @deprecated TODO Make private in 4.0.
669      */
670     @Deprecated
671     public RandomStringUtils() {
672         this(SECURE_SUPPLIER);
673     }
674 
675     private RandomStringUtils(final Supplier<RandomUtils> random) {
676         this.random = random;
677     }
678 
679     /**
680      * Creates a random string whose length is the number of characters specified.
681      *
682      * <p>
683      * Characters will be chosen from the set of all characters.
684      * </p>
685      *
686      * @param count the length of random string to create.
687      * @return the random string.
688      * @throws IllegalArgumentException if {@code count} &lt; 0.
689      * @since 3.16.0
690      */
691     public String next(final int count) {
692         return next(count, false, false);
693     }
694 
695     /**
696      * Creates a random string whose length is the number of characters specified.
697      *
698      * <p>
699      * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
700      * </p>
701      *
702      * @param count   the length of random string to create.
703      * @param letters if {@code true}, generated string may include alphabetic characters.
704      * @param numbers if {@code true}, generated string may include numeric characters.
705      * @return the random string.
706      * @throws IllegalArgumentException if {@code count} &lt; 0.
707      * @since 3.16.0
708      */
709     public String next(final int count, final boolean letters, final boolean numbers) {
710         return next(count, 0, 0, letters, numbers);
711     }
712 
713     /**
714      * Creates a random string whose length is the number of characters specified.
715      *
716      * <p>
717      * Characters will be chosen from the set of characters specified.
718      * </p>
719      *
720      * @param count the length of random string to create.
721      * @param chars the character array containing the set of characters to use, may be null.
722      * @return the random string.
723      * @throws IllegalArgumentException if {@code count} &lt; 0.
724      * @since 3.16.0
725      */
726     public String next(final int count, final char... chars) {
727         if (chars == null) {
728             return random(count, 0, 0, false, false, null, random());
729         }
730         return random(count, 0, chars.length, false, false, chars, random());
731     }
732 
733     /**
734      * Creates a random string whose length is the number of characters specified.
735      *
736      * <p>
737      * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
738      * </p>
739      *
740      * @param count   the length of random string to create.
741      * @param start   the position in set of chars to start at.
742      * @param end     the position in set of chars to end before.
743      * @param letters if {@code true}, generated string may include alphabetic characters.
744      * @param numbers if {@code true}, generated string may include numeric characters.
745      * @return the random string.
746      * @throws IllegalArgumentException if {@code count} &lt; 0.
747      * @since 3.16.0
748      */
749     public String next(final int count, final int start, final int end, final boolean letters, final boolean numbers) {
750         return random(count, start, end, letters, numbers, null, random());
751     }
752 
753     /**
754      * Creates a random string based on a variety of options, using default source of randomness.
755      *
756      * <p>
757      * This method has exactly the same semantics as {@link #random(int,int,int,boolean,boolean,char[],Random)}, but
758      * instead of using an externally supplied source of randomness, it uses the internal static {@link Random}
759      * instance.
760      * </p>
761      *
762      * @param count   the length of random string to create.
763      * @param start   the position in set of chars to start at.
764      * @param end     the position in set of chars to end before.
765      * @param letters if {@code true}, generated string may include alphabetic characters.
766      * @param numbers if {@code true}, generated string may include numeric characters.
767      * @param chars   the set of chars to choose randoms from. If {@code null}, then it will use the set of all chars.
768      * @return the random string.
769      * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
770      * @throws IllegalArgumentException       if {@code count} &lt; 0.
771      */
772     public String next(final int count, final int start, final int end, final boolean letters, final boolean numbers,
773             final char... chars) {
774         return random(count, start, end, letters, numbers, chars, random());
775     }
776 
777     /**
778      * Creates a random string whose length is the number of characters specified.
779      *
780      * <p>
781      * Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set
782      * of all characters is used.
783      * </p>
784      *
785      * @param count the length of random string to create.
786      * @param chars the String containing the set of characters to use, may be null, but must not be empty.
787      * @return the random string.
788      * @throws IllegalArgumentException if {@code count} &lt; 0 or the string is empty.
789      * @since 3.16.0
790      */
791     public String next(final int count, final String chars) {
792         if (chars == null) {
793             return random(count, 0, 0, false, false, null, random());
794         }
795         return next(count, chars.toCharArray());
796     }
797 
798     /**
799      * Creates a random string whose length is the number of characters specified.
800      *
801      * <p>
802      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
803      * </p>
804      *
805      * @param count the length of random string to create.
806      * @return the random string.
807      * @throws IllegalArgumentException if {@code count} &lt; 0.
808      */
809     public String nextAlphabetic(final int count) {
810         return next(count, true, false);
811     }
812 
813     /**
814      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
815      *
816      * <p>
817      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
818      * </p>
819      *
820      * @param minLengthInclusive the inclusive minimum length of the string to generate.
821      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
822      * @return the random string.
823      * @since 3.5
824      */
825     public String nextAlphabetic(final int minLengthInclusive, final int maxLengthExclusive) {
826         return nextAlphabetic(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
827     }
828 
829     /**
830      * Creates a random string whose length is the number of characters specified.
831      *
832      * <p>
833      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
834      * </p>
835      *
836      * @param count the length of random string to create.
837      * @return the random string.
838      * @throws IllegalArgumentException if {@code count} &lt; 0.
839      */
840     public String nextAlphanumeric(final int count) {
841         return next(count, true, true);
842     }
843 
844     /**
845      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
846      *
847      * <p>
848      * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
849      * </p>
850      *
851      * @param minLengthInclusive the inclusive minimum length of the string to generate.
852      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
853      * @return the random string.
854      * @since 3.5
855      */
856     public String nextAlphanumeric(final int minLengthInclusive, final int maxLengthExclusive) {
857         return nextAlphanumeric(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
858     }
859 
860     /**
861      * Creates a random string whose length is the number of characters specified.
862      *
863      * <p>
864      * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
865      * (inclusive).
866      * </p>
867      *
868      * @param count the length of random string to create.
869      * @return the random string.
870      * @throws IllegalArgumentException if {@code count} &lt; 0.
871      */
872     public String nextAscii(final int count) {
873         return next(count, 32, 127, false, false);
874     }
875 
876     /**
877      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
878      *
879      * <p>
880      * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
881      * (inclusive).
882      * </p>
883      *
884      * @param minLengthInclusive the inclusive minimum length of the string to generate.
885      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
886      * @return the random string.
887      * @since 3.5
888      */
889     public String nextAscii(final int minLengthInclusive, final int maxLengthExclusive) {
890         return nextAscii(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
891     }
892 
893     /**
894      * Creates a random string whose length is the number of characters specified.
895      *
896      * <p>
897      * Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character
898      * class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
899      * </p>
900      *
901      * @param count the length of random string to create.
902      * @return the random string.
903      * @throws IllegalArgumentException if {@code count} &lt; 0.
904      * @since 3.5
905      */
906     public String nextGraph(final int count) {
907         return next(count, 33, 126, false, false);
908     }
909 
910     /**
911      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
912      *
913      * <p>
914      * Characters will be chosen from the set of \p{Graph} characters.
915      * </p>
916      *
917      * @param minLengthInclusive the inclusive minimum length of the string to generate.
918      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
919      * @return the random string.
920      * @since 3.5
921      */
922     public String nextGraph(final int minLengthInclusive, final int maxLengthExclusive) {
923         return nextGraph(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
924     }
925 
926     /**
927      * Creates a random string whose length is the number of characters specified.
928      *
929      * <p>
930      * Characters will be chosen from the set of numeric characters.
931      * </p>
932      *
933      * @param count the length of random string to create.
934      * @return the random string.
935      * @throws IllegalArgumentException if {@code count} &lt; 0.
936      */
937     public String nextNumeric(final int count) {
938         return next(count, false, true);
939     }
940 
941     /**
942      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
943      *
944      * <p>
945      * Characters will be chosen from the set of \p{Digit} characters.
946      * </p>
947      *
948      * @param minLengthInclusive the inclusive minimum length of the string to generate.
949      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
950      * @return the random string.
951      * @since 3.5
952      */
953     public String nextNumeric(final int minLengthInclusive, final int maxLengthExclusive) {
954         return nextNumeric(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
955     }
956 
957     /**
958      * Creates a random string whose length is the number of characters specified.
959      *
960      * <p>
961      * Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character
962      * class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
963      * </p>
964      *
965      * @param count the length of random string to create.
966      * @return the random string.
967      * @throws IllegalArgumentException if {@code count} &lt; 0.
968      * @since 3.5
969      * @since 3.16.0
970      */
971     public String nextPrint(final int count) {
972         return next(count, 32, 126, false, false);
973     }
974 
975     /**
976      * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
977      *
978      * <p>
979      * Characters will be chosen from the set of \p{Print} characters.
980      * </p>
981      *
982      * @param minLengthInclusive the inclusive minimum length of the string to generate.
983      * @param maxLengthExclusive the exclusive maximum length of the string to generate.
984      * @return the random string.
985      * @since 3.16.0
986      */
987     public String nextPrint(final int minLengthInclusive, final int maxLengthExclusive) {
988         return nextPrint(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
989     }
990 
991     /**
992      * Gets the Random.
993      *
994      * @return the Random.
995      */
996     private Random random() {
997         return randomUtils().random();
998     }
999 
1000     /**
1001      * Gets the RandomUtils.
1002      *
1003      * @return the RandomUtils.
1004      */
1005     private RandomUtils randomUtils() {
1006         return random.get();
1007     }
1008 
1009     @Override
1010     public String toString() {
1011         return "RandomStringUtils [random=" + random() + "]";
1012     }
1013 
1014 }