    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.lang3;
    018
    019import java.security.SecureRandom;
    020import java.security.Security;
    021import java.util.Random;
    022import java.util.concurrent.ThreadLocalRandom;
    023import java.util.function.Supplier;
    024
    025/**
    026 * Generates random {@link String}s.
    027 * <p>
    028 * Use {@link #secure()} to get the singleton instance based on {@link SecureRandom#SecureRandom()} which uses a secure random number generator implementing the
    029 * default random number algorithm.
    030 * </p>
    031 * <p>
    032 * Use {@link #secureStrong()} to get the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an instance that was selected by using
    033 * the algorithms/providers specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
    034 * </p>
    035 * <p>
    036 * Use {@link #insecure()} to get the singleton instance based on {@link ThreadLocalRandom#current()} <b>which is not cryptographically secure</b>. In addition,
    037 * instances do not use a cryptographically random seed unless the {@linkplain System#getProperty system property} {@code java.util.secureRandomSeed} is set to
    038 * {@code true}.
    039 * </p>
    040 * <p>
    041 * Starting in version 3.17.0, the method {@link #secure()} uses {@link SecureRandom#SecureRandom()} instead of {@link SecureRandom#getInstanceStrong()}, and
    042 * adds {@link #secureStrong()}.
    043 * </p>
    044 * <p>
    045 * Starting in version 3.16.0, this class uses {@link #secure()} for static methods and adds {@link #insecure()}.
    046 * </p>
    047 * <p>
    048 * Starting in version 3.15.0, this class uses {@link SecureRandom#getInstanceStrong()} for static methods.
    049 * </p>
    050 * <p>
    051 * Before version 3.15.0, this class used {@link ThreadLocalRandom#current()} for static methods, which is not cryptographically secure.
    052 * </p>
    053 * <p>
    054 * RandomStringUtils is intended for simple use cases. For more advanced use cases consider using Apache Commons Text's
    055 * <a href= "https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/RandomStringGenerator.html"> RandomStringGenerator</a>
    056 * instead.
    057 * </p>
    058 * <p>
    059 * The Apache Commons project provides <a href="https://commons.apache.org/proper/commons-rng/">Commons RNG</a> dedicated to pseudo-random number generation,
    060 * that may be a better choice for applications with more stringent requirements (performance and/or correctness).
    061 * </p>
    062 * <p>
    063 * 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
    064 * 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
    065 * (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
    066 * surrogate.
    067 * </p>
    068 * <p>
    069 * #ThreadSafe#
    070 * </p>
    071 *
    072 * @see #secure()
    073 * @see #secureStrong()
    074 * @see #insecure()
    075 * @see SecureRandom#SecureRandom()
    076 * @see SecureRandom#getInstanceStrong()
    077 * @see ThreadLocalRandom#current()
    078 * @see RandomUtils
    079 * @since 1.0
    080 */
    081public class RandomStringUtils {
    082
    083    private static final Supplier<RandomUtils> SECURE_SUPPLIER = RandomUtils::secure;
    084
    085    private static RandomStringUtils INSECURE = new RandomStringUtils(RandomUtils::insecure);
    086
    087    private static RandomStringUtils SECURE = new RandomStringUtils(SECURE_SUPPLIER);
    088
    089    private static RandomStringUtils SECURE_STRONG = new RandomStringUtils(RandomUtils::secureStrong);
    090
    091    private static final char[] ALPHANUMERICAL_CHARS = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
    092            'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
    093            'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1',
    094            '2', '3', '4', '5', '6', '7', '8', '9' };
    095
    096    /**
    097     * Gets the singleton instance based on {@link ThreadLocalRandom#current()}; <b>which is not cryptographically
    098     * secure</b>; use {@link #secure()} to use an algorithms/providers specified in the
    099     * {@code securerandom.strongAlgorithms} {@link Security} property.
    100     * <p>
    101     * The method {@link ThreadLocalRandom#current()} is called on-demand.
    102     * </p>
    103     *
    104     * @return the singleton instance based on {@link ThreadLocalRandom#current()}.
    105     * @see ThreadLocalRandom#current()
    106     * @see #secure()
    107     * @since 3.16.0
    108     */
    109    public static RandomStringUtils insecure() {
    110        return INSECURE;
    111    }
    112
    113    /**
    114     * Creates a random string whose length is the number of characters specified.
    115     *
    116     * <p>
    117     * Characters will be chosen from the set of all characters.
    118     * </p>
    119     *
    120     * @param count the length of random string to create
    121     * @return the random string
    122     * @throws IllegalArgumentException if {@code count} &lt; 0.
    123     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    124     */
    125    @Deprecated
    126    public static String random(final int count) {
    127        return secure().next(count);
    128    }
    129
    130    /**
    131     * Creates a random string whose length is the number of characters specified.
    132     *
    133     * <p>
    134     * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
    135     * </p>
    136     *
    137     * @param count   the length of random string to create
    138     * @param letters if {@code true}, generated string may include alphabetic characters
    139     * @param numbers if {@code true}, generated string may include numeric characters
    140     * @return the random string
    141     * @throws IllegalArgumentException if {@code count} &lt; 0.
    142     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    143     */
    144    @Deprecated
    145    public static String random(final int count, final boolean letters, final boolean numbers) {
    146        return secure().next(count, letters, numbers);
    147    }
    148
    149    /**
    150     * Creates a random string whose length is the number of characters specified.
    151     *
    152     * <p>
    153     * Characters will be chosen from the set of characters specified.
    154     * </p>
    155     *
    156     * @param count the length of random string to create
    157     * @param chars the character array containing the set of characters to use, may be null
    158     * @return the random string
    159     * @throws IllegalArgumentException if {@code count} &lt; 0.
    160     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    161     */
    162    @Deprecated
    163    public static String random(final int count, final char... chars) {
    164        return secure().next(count, chars);
    165    }
    166
    167    /**
    168     * Creates a random string whose length is the number of characters specified.
    169     *
    170     * <p>
    171     * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
    172     * </p>
    173     *
    174     * @param count   the length of random string to create
    175     * @param start   the position in set of chars to start at
    176     * @param end     the position in set of chars to end before
    177     * @param letters if {@code true}, generated string may include alphabetic characters
    178     * @param numbers if {@code true}, generated string may include numeric characters
    179     * @return the random string
    180     * @throws IllegalArgumentException if {@code count} &lt; 0.
    181     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    182     */
    183    @Deprecated
    184    public static String random(final int count, final int start, final int end, final boolean letters,
    185            final boolean numbers) {
    186        return secure().next(count, start, end, letters, numbers);
    187    }
    188
    189    /**
    190     * Creates a random string based on a variety of options, using default source of randomness.
    191     *
    192     * <p>
    193     * This method has exactly the same semantics as {@link #random(int,int,int,boolean,boolean,char[],Random)}, but
    194     * instead of using an externally supplied source of randomness, it uses the internal static {@link Random}
    195     * instance.
    196     * </p>
    197     *
    198     * @param count   the length of random string to create
    199     * @param start   the position in set of chars to start at
    200     * @param end     the position in set of chars to end before
    201     * @param letters if {@code true}, generated string may include alphabetic characters
    202     * @param numbers if {@code true}, generated string may include numeric characters
    203     * @param chars   the set of chars to choose randoms from. If {@code null}, then it will use the set of all chars.
    204     * @return the random string
    205     * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
    206     * @throws IllegalArgumentException       if {@code count} &lt; 0.
    207     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    208     */
    209    @Deprecated
    210    public static String random(final int count, final int start, final int end, final boolean letters,
    211            final boolean numbers, final char... chars) {
    212        return secure().next(count, start, end, letters, numbers, chars);
    213    }
    214
    215    /**
    216     * Creates a random string based on a variety of options, using supplied source of randomness.
    217     *
    218     * <p>
    219     * If start and end are both {@code 0}, start and end are set to {@code ' '} and {@code 'z'}, the ASCII printable
    220     * characters, will be used, unless letters and numbers are both {@code false}, in which case, start and end are set
    221     * to {@code 0} and {@link Character#MAX_CODE_POINT}.
    222     *
    223     * <p>
    224     * If set is not {@code null}, characters between start and end are chosen.
    225     * </p>
    226     *
    227     * <p>
    228     * This method accepts a user-supplied {@link Random} instance to use as a source of randomness. By seeding a single
    229     * {@link Random} instance with a fixed seed and using it for each call, the same random sequence of strings can be
    230     * generated repeatedly and predictably.
    231     * </p>
    232     *
    233     * @param count   the length of random string to create
    234     * @param start   the position in set of chars to start at (inclusive)
    235     * @param end     the position in set of chars to end before (exclusive)
    236     * @param letters if {@code true}, generated string may include alphabetic characters
    237     * @param numbers if {@code true}, generated string may include numeric characters
    238     * @param chars   the set of chars to choose randoms from, must not be empty. If {@code null}, then it will use the
    239     *                set of all chars.
    240     * @param random  a source of randomness.
    241     * @return the random string
    242     * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
    243     * @throws IllegalArgumentException       if {@code count} &lt; 0 or the provided chars array is empty.
    244     * @since 2.0
    245     */
    246    public static String random(int count, int start, int end, final boolean letters, final boolean numbers,
    247            final char[] chars, final Random random) {
    248        if (count == 0) {
    249            return StringUtils.EMPTY;
    250        }
    251        if (count < 0) {
    252            throw new IllegalArgumentException("Requested random string length " + count + " is less than 0.");
    253        }
    254        if (chars != null && chars.length == 0) {
    255            throw new IllegalArgumentException("The chars array must not be empty");
    256        }
    257
    258        if (start == 0 && end == 0) {
    259            if (chars != null) {
    260                end = chars.length;
    261            } else if (!letters && !numbers) {
    262                end = Character.MAX_CODE_POINT;
    263            } else {
    264                end = 'z' + 1;
    265                start = ' ';
    266            }
    267        } else if (end <= start) {
    268            throw new IllegalArgumentException(
    269                    "Parameter end (" + end + ") must be greater than start (" + start + ")");
    270        } else if (start < 0 || end < 0) {
    271            throw new IllegalArgumentException("Character positions MUST be >= 0");
    272        }
    273
    274        if (end > Character.MAX_CODE_POINT) {
    275            // Technically, it should be `Character.MAX_CODE_POINT+1` as `end` is excluded
    276            // But the character `Character.MAX_CODE_POINT` is private use, so it would anyway be excluded
    277            end = Character.MAX_CODE_POINT;
    278        }
    279
    280        // Optimize generation of full alphanumerical characters
    281        // Normally, we would need to pick a 7-bit integer, since gap = 'z' - '0' + 1 = 75 > 64
    282        // In turn, this would make us reject the sampling with probability 1 - 62 / 2^7 > 1 / 2
    283        // Instead we can pick directly from the right set of 62 characters, which requires
    284        // picking a 6-bit integer and only rejecting with probability 2 / 64 = 1 / 32
    285        if (chars == null && letters && numbers && start <= '0' && end >= 'z' + 1) {
    286            return random(count, 0, 0, false, false, ALPHANUMERICAL_CHARS, random);
    287        }
    288
    289        // Optimize start and end when filtering by letters and/or numbers:
    290        // The range provided may be too large since we filter anyway afterward.
    291        // Note the use of Math.min/max (as opposed to setting start to '0' for example),
    292        // since it is possible the range start/end excludes some of the letters/numbers,
    293        // e.g., it is possible that start already is '1' when numbers = true, and start
    294        // needs to stay equal to '1' in that case.
    295        if (chars == null) {
    296            if (letters && numbers) {
    297                start = Math.max('0', start);
    298                end = Math.min('z' + 1, end);
    299            } else if (numbers) {
    300                // just numbers, no letters
    301                start = Math.max('0', start);
    302                end = Math.min('9' + 1, end);
    303            } else if (letters) {
    304                // just letters, no numbers
    305                start = Math.max('A', start);
    306                end = Math.min('z' + 1, end);
    307            }
    308        }
    309
    310        final int zeroDigitAscii = 48;
    311        final int firstLetterAscii = 65;
    312
    313        if (chars == null && (numbers && end <= zeroDigitAscii || letters && end <= firstLetterAscii)) {
    314            throw new IllegalArgumentException(
    315                    "Parameter end (" + end + ") must be greater then (" + zeroDigitAscii + ") for generating digits "
    316                            + "or greater then (" + firstLetterAscii + ") for generating letters.");
    317        }
    318
    319        final StringBuilder builder = new StringBuilder(count);
    320        final int gap = end - start;
    321        final int gapBits = Integer.SIZE - Integer.numberOfLeadingZeros(gap);
    322        // The size of the cache we use is an heuristic:
    323        // about twice the number of bytes required if no rejection
    324        // Ideally the cache size depends on multiple factor, including the cost of generating x bytes
    325        // of randomness as well as the probability of rejection. It is however not easy to know
    326        // those values programmatically for the general case.
    327        final CachedRandomBits arb = new CachedRandomBits((count * gapBits + 3) / 5 + 10, random);
    328
    329        while (count-- != 0) {
    330            // Generate a random value between start (included) and end (excluded)
    331            final int randomValue = arb.nextBits(gapBits) + start;
    332            // Rejection sampling if value too large
    333            if (randomValue >= end) {
    334                count++;
    335                continue;
    336            }
    337
    338            final int codePoint;
    339            if (chars == null) {
    340                codePoint = randomValue;
    341
    342                switch (Character.getType(codePoint)) {
    343                case Character.UNASSIGNED:
    344                case Character.PRIVATE_USE:
    345                case Character.SURROGATE:
    346                    count++;
    347                    continue;
    348                }
    349
    350            } else {
    351                codePoint = chars[randomValue];
    352            }
    353
    354            final int numberOfChars = Character.charCount(codePoint);
    355            if (count == 0 && numberOfChars > 1) {
    356                count++;
    357                continue;
    358            }
    359
    360            if (letters && Character.isLetter(codePoint) || numbers && Character.isDigit(codePoint)
    361                    || !letters && !numbers) {
    362                builder.appendCodePoint(codePoint);
    363
    364                if (numberOfChars == 2) {
    365                    count--;
    366                }
    367
    368            } else {
    369                count++;
    370            }
    371        }
    372        return builder.toString();
    373    }
    374
    375    /**
    376     * Creates a random string whose length is the number of characters specified.
    377     *
    378     * <p>
    379     * Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set
    380     * of all characters is used.
    381     * </p>
    382     *
    383     * @param count the length of random string to create
    384     * @param chars the String containing the set of characters to use, may be null, but must not be empty
    385     * @return the random string
    386     * @throws IllegalArgumentException if {@code count} &lt; 0 or the string is empty.
    387     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    388     */
    389    @Deprecated
    390    public static String random(final int count, final String chars) {
    391        return secure().next(count, chars);
    392    }
    393
    394    /**
    395     * Creates a random string whose length is the number of characters specified.
    396     *
    397     * <p>
    398     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
    399     * </p>
    400     *
    401     * @param count the length of random string to create
    402     * @return the random string
    403     * @throws IllegalArgumentException if {@code count} &lt; 0.
    404     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    405     */
    406    @Deprecated
    407    public static String randomAlphabetic(final int count) {
    408        return secure().nextAlphabetic(count);
    409    }
    410
    411    /**
    412     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    413     *
    414     * <p>
    415     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
    416     * </p>
    417     *
    418     * @param minLengthInclusive the inclusive minimum length of the string to generate
    419     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    420     * @return the random string
    421     * @since 3.5
    422     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    423     */
    424    @Deprecated
    425    public static String randomAlphabetic(final int minLengthInclusive, final int maxLengthExclusive) {
    426        return secure().nextAlphabetic(minLengthInclusive, maxLengthExclusive);
    427    }
    428
    429    /**
    430     * Creates a random string whose length is the number of characters specified.
    431     *
    432     * <p>
    433     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
    434     * </p>
    435     *
    436     * @param count the length of random string to create
    437     * @return the random string
    438     * @throws IllegalArgumentException if {@code count} &lt; 0.
    439     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    440     */
    441    @Deprecated
    442    public static String randomAlphanumeric(final int count) {
    443        return secure().nextAlphanumeric(count);
    444    }
    445
    446    /**
    447     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    448     *
    449     * <p>
    450     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
    451     * </p>
    452     *
    453     * @param minLengthInclusive the inclusive minimum length of the string to generate
    454     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    455     * @return the random string
    456     * @since 3.5
    457     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    458     */
    459    @Deprecated
    460    public static String randomAlphanumeric(final int minLengthInclusive, final int maxLengthExclusive) {
    461        return secure().nextAlphanumeric(minLengthInclusive, maxLengthExclusive);
    462    }
    463
    464    /**
    465     * Creates a random string whose length is the number of characters specified.
    466     *
    467     * <p>
    468     * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
    469     * (inclusive).
    470     * </p>
    471     *
    472     * @param count the length of random string to create
    473     * @return the random string
    474     * @throws IllegalArgumentException if {@code count} &lt; 0.
    475     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    476     */
    477    @Deprecated
    478    public static String randomAscii(final int count) {
    479        return secure().nextAscii(count);
    480    }
    481
    482    /**
    483     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    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 minLengthInclusive the inclusive minimum length of the string to generate
    491     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    492     * @return the random string
    493     * @since 3.5
    494     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    495     */
    496    @Deprecated
    497    public static String randomAscii(final int minLengthInclusive, final int maxLengthExclusive) {
    498        return secure().nextAscii(minLengthInclusive, maxLengthExclusive);
    499    }
    500
    501    /**
    502     * Creates a random string whose length is the number of characters specified.
    503     *
    504     * <p>
    505     * Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character
    506     * class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
    507     * </p>
    508     *
    509     * @param count the length of random string to create
    510     * @return the random string
    511     * @throws IllegalArgumentException if {@code count} &lt; 0.
    512     * @since 3.5
    513     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    514     */
    515    @Deprecated
    516    public static String randomGraph(final int count) {
    517        return secure().nextGraph(count);
    518    }
    519
    520    /**
    521     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    522     *
    523     * <p>
    524     * Characters will be chosen from the set of \p{Graph} characters.
    525     * </p>
    526     *
    527     * @param minLengthInclusive the inclusive minimum length of the string to generate
    528     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    529     * @return the random string
    530     * @since 3.5
    531     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    532     */
    533    @Deprecated
    534    public static String randomGraph(final int minLengthInclusive, final int maxLengthExclusive) {
    535        return secure().nextGraph(minLengthInclusive, maxLengthExclusive);
    536    }
    537
    538    /**
    539     * Creates a random string whose length is the number of characters specified.
    540     *
    541     * <p>
    542     * Characters will be chosen from the set of numeric characters.
    543     * </p>
    544     *
    545     * @param count the length of random string to create
    546     * @return the random string
    547     * @throws IllegalArgumentException if {@code count} &lt; 0.
    548     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    549     */
    550    @Deprecated
    551    public static String randomNumeric(final int count) {
    552        return secure().nextNumeric(count);
    553    }
    554
    555    /**
    556     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    557     *
    558     * <p>
    559     * Characters will be chosen from the set of \p{Digit} characters.
    560     * </p>
    561     *
    562     * @param minLengthInclusive the inclusive minimum length of the string to generate
    563     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    564     * @return the random string
    565     * @since 3.5
    566     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    567     */
    568    @Deprecated
    569    public static String randomNumeric(final int minLengthInclusive, final int maxLengthExclusive) {
    570        return secure().nextNumeric(minLengthInclusive, maxLengthExclusive);
    571    }
    572
    573    /**
    574     * Creates a random string whose length is the number of characters specified.
    575     *
    576     * <p>
    577     * Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character
    578     * class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
    579     * </p>
    580     *
    581     * @param count the length of random string to create
    582     * @return the random string
    583     * @throws IllegalArgumentException if {@code count} &lt; 0.
    584     * @since 3.5
    585     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    586     */
    587    @Deprecated
    588    public static String randomPrint(final int count) {
    589        return secure().nextPrint(count);
    590    }
    591
    592    /**
    593     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    594     *
    595     * <p>
    596     * Characters will be chosen from the set of \p{Print} characters.
    597     * </p>
    598     *
    599     * @param minLengthInclusive the inclusive minimum length of the string to generate
    600     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    601     * @return the random string
    602     * @since 3.5
    603     * @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
    604     */
    605    @Deprecated
    606    public static String randomPrint(final int minLengthInclusive, final int maxLengthExclusive) {
    607        return secure().nextPrint(minLengthInclusive, maxLengthExclusive);
    608    }
    609
    610    /**
    611     * Gets the singleton instance based on {@link SecureRandom#SecureRandom()} which uses a secure random number generator (RNG) implementing the default
    612     * random number algorithm.
    613     * <p>
    614     * The method {@link SecureRandom#SecureRandom()} is called on-demand.
    615     * </p>
    616     *
    617     * @return the singleton instance based on {@link SecureRandom#SecureRandom()}.
    618     * @see SecureRandom#SecureRandom()
    619     * @since 3.16.0
    620     */
    621    public static RandomStringUtils secure() {
    622        return SECURE;
    623    }
    624
    625    /**
    626     * Gets the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an algorithms/providers
    627     * specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
    628     * <p>
    629     * The method {@link SecureRandom#getInstanceStrong()} is called on-demand.
    630     * </p>
    631     *
    632     * @return the singleton instance based on {@link SecureRandom#getInstanceStrong()}.
    633     * @see SecureRandom#getInstanceStrong()
    634     * @since 3.17.0
    635     */
    636    public static RandomStringUtils secureStrong() {
    637        return SECURE_STRONG;
    638    }
    639
    640    private final Supplier<RandomUtils> random;
    641
    642    /**
    643     * {@link RandomStringUtils} instances should NOT be constructed in standard programming. Instead, the class should
    644     * be used as {@code RandomStringUtils.random(5);}.
    645     *
    646     * <p>
    647     * This constructor is public to permit tools that require a JavaBean instance to operate.
    648     * </p>
    649     *
    650     * @deprecated TODO Make private in 4.0.
    651     */
    652    @Deprecated
    653    public RandomStringUtils() {
    654        this(SECURE_SUPPLIER);
    655    }
    656
    657    private RandomStringUtils(final Supplier<RandomUtils> random) {
    658        this.random = random;
    659    }
    660
    661    /**
    662     * Creates a random string whose length is the number of characters specified.
    663     *
    664     * <p>
    665     * Characters will be chosen from the set of all characters.
    666     * </p>
    667     *
    668     * @param count the length of random string to create
    669     * @return the random string
    670     * @throws IllegalArgumentException if {@code count} &lt; 0.
    671     * @since 3.16.0
    672     */
    673    public String next(final int count) {
    674        return next(count, false, false);
    675    }
    676
    677    /**
    678     * Creates a random string whose length is the number of characters specified.
    679     *
    680     * <p>
    681     * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
    682     * </p>
    683     *
    684     * @param count   the length of random string to create
    685     * @param letters if {@code true}, generated string may include alphabetic characters
    686     * @param numbers if {@code true}, generated string may include numeric characters
    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, final boolean letters, final boolean numbers) {
    692        return next(count, 0, 0, letters, numbers);
    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 characters specified.
    700     * </p>
    701     *
    702     * @param count the length of random string to create
    703     * @param chars the character array containing the set of characters to use, may be null
    704     * @return the random string
    705     * @throws IllegalArgumentException if {@code count} &lt; 0.
    706     * @since 3.16.0
    707     */
    708    public String next(final int count, final char... chars) {
    709        if (chars == null) {
    710            return random(count, 0, 0, false, false, null, random());
    711        }
    712        return random(count, 0, chars.length, false, false, chars, random());
    713    }
    714
    715    /**
    716     * Creates a random string whose length is the number of characters specified.
    717     *
    718     * <p>
    719     * Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
    720     * </p>
    721     *
    722     * @param count   the length of random string to create
    723     * @param start   the position in set of chars to start at
    724     * @param end     the position in set of chars to end before
    725     * @param letters if {@code true}, generated string may include alphabetic characters
    726     * @param numbers if {@code true}, generated string may include numeric characters
    727     * @return the random string
    728     * @throws IllegalArgumentException if {@code count} &lt; 0.
    729     * @since 3.16.0
    730     */
    731    public String next(final int count, final int start, final int end, final boolean letters, final boolean numbers) {
    732        return random(count, start, end, letters, numbers, null, random());
    733    }
    734
    735    /**
    736     * Creates a random string based on a variety of options, using default source of randomness.
    737     *
    738     * <p>
    739     * This method has exactly the same semantics as {@link #random(int,int,int,boolean,boolean,char[],Random)}, but
    740     * instead of using an externally supplied source of randomness, it uses the internal static {@link Random}
    741     * instance.
    742     * </p>
    743     *
    744     * @param count   the length of random string to create
    745     * @param start   the position in set of chars to start at
    746     * @param end     the position in set of chars to end before
    747     * @param letters if {@code true}, generated string may include alphabetic characters
    748     * @param numbers if {@code true}, generated string may include numeric characters
    749     * @param chars   the set of chars to choose randoms from. If {@code null}, then it will use the set of all chars.
    750     * @return the random string
    751     * @throws ArrayIndexOutOfBoundsException if there are not {@code (end - start) + 1} characters in the set array.
    752     * @throws IllegalArgumentException       if {@code count} &lt; 0.
    753     */
    754    public String next(final int count, final int start, final int end, final boolean letters, final boolean numbers,
    755            final char... chars) {
    756        return random(count, start, end, letters, numbers, chars, random());
    757    }
    758
    759    /**
    760     * Creates a random string whose length is the number of characters specified.
    761     *
    762     * <p>
    763     * Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set
    764     * of all characters is used.
    765     * </p>
    766     *
    767     * @param count the length of random string to create
    768     * @param chars the String containing the set of characters to use, may be null, but must not be empty
    769     * @return the random string
    770     * @throws IllegalArgumentException if {@code count} &lt; 0 or the string is empty.
    771     * @since 3.16.0
    772     */
    773    public String next(final int count, final String chars) {
    774        if (chars == null) {
    775            return random(count, 0, 0, false, false, null, random());
    776        }
    777        return next(count, chars.toCharArray());
    778    }
    779
    780    /**
    781     * Creates a random string whose length is the number of characters specified.
    782     *
    783     * <p>
    784     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
    785     * </p>
    786     *
    787     * @param count the length of random string to create
    788     * @return the random string
    789     * @throws IllegalArgumentException if {@code count} &lt; 0.
    790     */
    791    public String nextAlphabetic(final int count) {
    792        return next(count, true, false);
    793    }
    794
    795    /**
    796     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    797     *
    798     * <p>
    799     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
    800     * </p>
    801     *
    802     * @param minLengthInclusive the inclusive minimum length of the string to generate
    803     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    804     * @return the random string
    805     * @since 3.5
    806     */
    807    public String nextAlphabetic(final int minLengthInclusive, final int maxLengthExclusive) {
    808        return nextAlphabetic(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    809    }
    810
    811    /**
    812     * Creates a random string whose length is the number of characters specified.
    813     *
    814     * <p>
    815     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
    816     * </p>
    817     *
    818     * @param count the length of random string to create
    819     * @return the random string
    820     * @throws IllegalArgumentException if {@code count} &lt; 0.
    821     */
    822    public String nextAlphanumeric(final int count) {
    823        return next(count, true, true);
    824    }
    825
    826    /**
    827     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    828     *
    829     * <p>
    830     * Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
    831     * </p>
    832     *
    833     * @param minLengthInclusive the inclusive minimum length of the string to generate
    834     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    835     * @return the random string
    836     * @since 3.5
    837     */
    838    public String nextAlphanumeric(final int minLengthInclusive, final int maxLengthExclusive) {
    839        return nextAlphanumeric(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    840    }
    841
    842    /**
    843     * Creates a random string whose length is the number of characters specified.
    844     *
    845     * <p>
    846     * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
    847     * (inclusive).
    848     * </p>
    849     *
    850     * @param count the length of random string to create
    851     * @return the random string
    852     * @throws IllegalArgumentException if {@code count} &lt; 0.
    853     */
    854    public String nextAscii(final int count) {
    855        return next(count, 32, 127, false, false);
    856    }
    857
    858    /**
    859     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    860     *
    861     * <p>
    862     * Characters will be chosen from the set of characters whose ASCII value is between {@code 32} and {@code 126}
    863     * (inclusive).
    864     * </p>
    865     *
    866     * @param minLengthInclusive the inclusive minimum length of the string to generate
    867     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    868     * @return the random string
    869     * @since 3.5
    870     */
    871    public String nextAscii(final int minLengthInclusive, final int maxLengthExclusive) {
    872        return nextAscii(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    873    }
    874
    875    /**
    876     * Creates a random string whose length is the number of characters specified.
    877     *
    878     * <p>
    879     * Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character
    880     * class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
    881     * </p>
    882     *
    883     * @param count the length of random string to create
    884     * @return the random string
    885     * @throws IllegalArgumentException if {@code count} &lt; 0.
    886     * @since 3.5
    887     */
    888    public String nextGraph(final int count) {
    889        return next(count, 33, 126, false, false);
    890    }
    891
    892    /**
    893     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    894     *
    895     * <p>
    896     * Characters will be chosen from the set of \p{Graph} characters.
    897     * </p>
    898     *
    899     * @param minLengthInclusive the inclusive minimum length of the string to generate
    900     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    901     * @return the random string
    902     * @since 3.5
    903     */
    904    public String nextGraph(final int minLengthInclusive, final int maxLengthExclusive) {
    905        return nextGraph(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    906    }
    907
    908    /**
    909     * Creates a random string whose length is the number of characters specified.
    910     *
    911     * <p>
    912     * Characters will be chosen from the set of numeric characters.
    913     * </p>
    914     *
    915     * @param count the length of random string to create
    916     * @return the random string
    917     * @throws IllegalArgumentException if {@code count} &lt; 0.
    918     */
    919    public String nextNumeric(final int count) {
    920        return next(count, false, true);
    921    }
    922
    923    /**
    924     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    925     *
    926     * <p>
    927     * Characters will be chosen from the set of \p{Digit} characters.
    928     * </p>
    929     *
    930     * @param minLengthInclusive the inclusive minimum length of the string to generate
    931     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    932     * @return the random string
    933     * @since 3.5
    934     */
    935    public String nextNumeric(final int minLengthInclusive, final int maxLengthExclusive) {
    936        return nextNumeric(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    937    }
    938
    939    /**
    940     * Creates a random string whose length is the number of characters specified.
    941     *
    942     * <p>
    943     * Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character
    944     * class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
    945     * </p>
    946     *
    947     * @param count the length of random string to create
    948     * @return the random string
    949     * @throws IllegalArgumentException if {@code count} &lt; 0.
    950     * @since 3.5
    951     * @since 3.16.0
    952     */
    953    public String nextPrint(final int count) {
    954        return next(count, 32, 126, false, false);
    955    }
    956
    957    /**
    958     * Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
    959     *
    960     * <p>
    961     * Characters will be chosen from the set of \p{Print} characters.
    962     * </p>
    963     *
    964     * @param minLengthInclusive the inclusive minimum length of the string to generate
    965     * @param maxLengthExclusive the exclusive maximum length of the string to generate
    966     * @return the random string
    967     * @since 3.16.0
    968     */
    969    public String nextPrint(final int minLengthInclusive, final int maxLengthExclusive) {
    970        return nextPrint(randomUtils().randomInt(minLengthInclusive, maxLengthExclusive));
    971    }
    972
    973    /**
    974     * Gets the Random.
    975     *
    976     * @return the Random.
    977     */
    978    private Random random() {
    979        return randomUtils().random();
    980    }
    981
    982    /**
    983     * Gets the RandomUtils.
    984     *
    985     * @return the RandomUtils.
    986     */
    987    private RandomUtils randomUtils() {
    988        return random.get();
    989    }
    990
    991    @Override
    992    public String toString() {
    993        return "RandomStringUtils [random=" + random() + "]";
    994    }
    995
    996}