public class RandomStringUtils extends Object
Strings.
Use secure() to get the singleton instance based on SecureRandom() which uses a secure random number generator implementing the
default random number algorithm.
Use secureStrong() to get the singleton instance based on SecureRandom.getInstanceStrong() which uses an instance that was selected by using
the algorithms/providers specified in the securerandom.strongAlgorithms Security property.
Use insecure() to get the singleton instance based on ThreadLocalRandom.current() which is not cryptographically secure. In addition,
instances do not use a cryptographically random seed unless the system property java.util.secureRandomSeed is set to
true.
Starting in version 3.17.0, the method secure() uses SecureRandom() instead of SecureRandom.getInstanceStrong(), and
adds secureStrong().
Starting in version 3.16.0, this class uses secure() for static methods and adds insecure().
Starting in version 3.15.0, this class uses SecureRandom.getInstanceStrong() for static methods.
Before version 3.15.0, this class used ThreadLocalRandom.current() for static methods, which is not cryptographically secure.
RandomStringUtils is intended for simple use cases. For more advanced use cases consider using Apache Commons Text's RandomStringGenerator instead.
The Apache Commons project provides Commons RNG dedicated to pseudo-random number generation, that may be a better choice for applications with more stringent requirements (performance and/or correctness).
Note that private high surrogate characters are ignored. These are Unicode characters that fall between the values 56192 (db80) and 56319 (dbff) as 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 (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 surrogate.
#ThreadSafe#
secure(),
secureStrong(),
insecure(),
SecureRandom(),
SecureRandom.getInstanceStrong(),
ThreadLocalRandom.current(),
RandomUtils| Constructor and Description |
|---|
RandomStringUtils()
Deprecated.
TODO Make private in 4.0.
|
| Modifier and Type | Method and Description |
|---|---|
static RandomStringUtils |
insecure()
Gets the singleton instance based on
ThreadLocalRandom.current(); which is not cryptographically
secure; use secure() to use an algorithms/providers specified in the
securerandom.strongAlgorithms Security property. |
String |
next(int count)
Creates a random string whose length is the number of characters specified.
|
String |
next(int count,
boolean letters,
boolean numbers)
Creates a random string whose length is the number of characters specified.
|
String |
next(int count,
char... chars)
Creates a random string whose length is the number of characters specified.
|
String |
next(int count,
int start,
int end,
boolean letters,
boolean numbers)
Creates a random string whose length is the number of characters specified.
|
String |
next(int count,
int start,
int end,
boolean letters,
boolean numbers,
char... chars)
Creates a random string based on a variety of options, using default source of randomness.
|
String |
next(int count,
String chars)
Creates a random string whose length is the number of characters specified.
|
String |
nextAlphabetic(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextAlphabetic(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
String |
nextAlphanumeric(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextAlphanumeric(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
String |
nextAscii(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextAscii(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
String |
nextGraph(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextGraph(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
String |
nextNumeric(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextNumeric(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
String |
nextPrint(int count)
Creates a random string whose length is the number of characters specified.
|
String |
nextPrint(int minLengthInclusive,
int maxLengthExclusive)
Creates a random string whose length is between the inclusive minimum and the exclusive maximum.
|
static String |
random(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
random(int count,
boolean letters,
boolean numbers)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
random(int count,
char... chars)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
random(int count,
int start,
int end,
boolean letters,
boolean numbers)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
random(int count,
int start,
int end,
boolean letters,
boolean numbers,
char... chars)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
random(int count,
int start,
int end,
boolean letters,
boolean numbers,
char[] chars,
Random random)
Creates a random string based on a variety of options, using supplied source of randomness.
|
static String |
random(int count,
String chars)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAlphabetic(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAlphabetic(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAlphanumeric(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAlphanumeric(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAscii(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomAscii(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomGraph(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomGraph(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomNumeric(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomNumeric(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomPrint(int count)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static String |
randomPrint(int minLengthInclusive,
int maxLengthExclusive)
Deprecated.
Use
secure(), secureStrong(),or insecure(). |
static RandomStringUtils |
secure()
Gets the singleton instance based on
SecureRandom() which uses a secure random number generator (RNG) implementing the default
random number algorithm. |
static RandomStringUtils |
secureStrong()
Gets the singleton instance based on
SecureRandom.getInstanceStrong() which uses an algorithms/providers
specified in the securerandom.strongAlgorithms Security property. |
String |
toString() |
@Deprecated public RandomStringUtils()
RandomStringUtils instances should NOT be constructed in standard programming. Instead, the class should
be used as RandomStringUtils.random(5);.
This constructor is public to permit tools that require a JavaBean instance to operate.
public static RandomStringUtils insecure()
ThreadLocalRandom.current(); which is not cryptographically
secure; use secure() to use an algorithms/providers specified in the
securerandom.strongAlgorithms Security property.
The method ThreadLocalRandom.current() is called on-demand.
ThreadLocalRandom.current().ThreadLocalRandom.current(),
secure()@Deprecated public static String random(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of all characters.
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String random(int count, boolean letters, boolean numbers)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
count - the length of random string to createletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric charactersIllegalArgumentException - if count < 0.@Deprecated public static String random(int count, char... chars)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of characters specified.
count - the length of random string to createchars - the character array containing the set of characters to use, may be nullIllegalArgumentException - if count < 0.@Deprecated public static String random(int count, int start, int end, boolean letters, boolean numbers)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
count - the length of random string to createstart - the position in set of chars to start atend - the position in set of chars to end beforeletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric charactersIllegalArgumentException - if count < 0.@Deprecated public static String random(int count, int start, int end, boolean letters, boolean numbers, char... chars)
secure(), secureStrong(),or insecure().
This method has exactly the same semantics as random(int,int,int,boolean,boolean,char[],Random), but
instead of using an externally supplied source of randomness, it uses the internal static Random
instance.
count - the length of random string to createstart - the position in set of chars to start atend - the position in set of chars to end beforeletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric characterschars - the set of chars to choose randoms from. If null, then it will use the set of all chars.ArrayIndexOutOfBoundsException - if there are not (end - start) + 1 characters in the set array.IllegalArgumentException - if count < 0.public static String random(int count, int start, int end, boolean letters, boolean numbers, char[] chars, Random random)
If start and end are both 0, start and end are set to ' ' and 'z', the ASCII printable
characters, will be used, unless letters and numbers are both false, in which case, start and end are set
to 0 and Character.MAX_CODE_POINT.
If set is not null, characters between start and end are chosen.
This method accepts a user-supplied Random instance to use as a source of randomness. By seeding a single
Random instance with a fixed seed and using it for each call, the same random sequence of strings can be
generated repeatedly and predictably.
count - the length of random string to createstart - the position in set of chars to start at (inclusive)end - the position in set of chars to end before (exclusive)letters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric characterschars - the set of chars to choose randoms from, must not be empty. If null, then it will use the
set of all chars.random - a source of randomness.ArrayIndexOutOfBoundsException - if there are not (end - start) + 1 characters in the set array.IllegalArgumentException - if count < 0 or the provided chars array is empty.@Deprecated public static String random(int count, String chars)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set of all characters is used.
count - the length of random string to createchars - the String containing the set of characters to use, may be null, but must not be emptyIllegalArgumentException - if count < 0 or the string is empty.@Deprecated public static String randomAlphabetic(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomAlphabetic(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generate@Deprecated public static String randomAlphanumeric(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomAlphanumeric(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generate@Deprecated public static String randomAscii(int count)
secure(), secureStrong(),or insecure().
Characters will be chosen from the set of characters whose ASCII value is between 32 and 126
(inclusive).
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomAscii(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().
Characters will be chosen from the set of characters whose ASCII value is between 32 and 126
(inclusive).
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generate@Deprecated public static String randomGraph(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomGraph(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of \p{Graph} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generate@Deprecated public static String randomNumeric(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of numeric characters.
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomNumeric(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of \p{Digit} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generate@Deprecated public static String randomPrint(int count)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
count - the length of random string to createIllegalArgumentException - if count < 0.@Deprecated public static String randomPrint(int minLengthInclusive, int maxLengthExclusive)
secure(), secureStrong(),or insecure().Characters will be chosen from the set of \p{Print} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic static RandomStringUtils secure()
SecureRandom() which uses a secure random number generator (RNG) implementing the default
random number algorithm.
The method SecureRandom() is called on-demand.
SecureRandom().SecureRandom()public static RandomStringUtils secureStrong()
SecureRandom.getInstanceStrong() which uses an algorithms/providers
specified in the securerandom.strongAlgorithms Security property.
The method SecureRandom.getInstanceStrong() is called on-demand.
SecureRandom.getInstanceStrong().SecureRandom.getInstanceStrong()public String next(int count)
Characters will be chosen from the set of all characters.
count - the length of random string to createIllegalArgumentException - if count < 0.public String next(int count, boolean letters, boolean numbers)
Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
count - the length of random string to createletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric charactersIllegalArgumentException - if count < 0.public String next(int count, char... chars)
Characters will be chosen from the set of characters specified.
count - the length of random string to createchars - the character array containing the set of characters to use, may be nullIllegalArgumentException - if count < 0.public String next(int count, int start, int end, boolean letters, boolean numbers)
Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
count - the length of random string to createstart - the position in set of chars to start atend - the position in set of chars to end beforeletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric charactersIllegalArgumentException - if count < 0.public String next(int count, int start, int end, boolean letters, boolean numbers, char... chars)
This method has exactly the same semantics as random(int,int,int,boolean,boolean,char[],Random), but
instead of using an externally supplied source of randomness, it uses the internal static Random
instance.
count - the length of random string to createstart - the position in set of chars to start atend - the position in set of chars to end beforeletters - if true, generated string may include alphabetic charactersnumbers - if true, generated string may include numeric characterschars - the set of chars to choose randoms from. If null, then it will use the set of all chars.ArrayIndexOutOfBoundsException - if there are not (end - start) + 1 characters in the set array.IllegalArgumentException - if count < 0.public String next(int count, String chars)
Characters will be chosen from the set of characters specified by the string, must not be empty. If null, the set of all characters is used.
count - the length of random string to createchars - the String containing the set of characters to use, may be null, but must not be emptyIllegalArgumentException - if count < 0 or the string is empty.public String nextAlphabetic(int count)
Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextAlphabetic(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z).
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic String nextAlphanumeric(int count)
Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextAlphanumeric(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of Latin alphabetic characters (a-z, A-Z) and the digits 0-9.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic String nextAscii(int count)
Characters will be chosen from the set of characters whose ASCII value is between 32 and 126
(inclusive).
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextAscii(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of characters whose ASCII value is between 32 and 126
(inclusive).
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic String nextGraph(int count)
Characters will be chosen from the set of characters which match the POSIX [:graph:] regular expression character class. This class contains all visible ASCII characters (i.e. anything except spaces and control characters).
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextGraph(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of \p{Graph} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic String nextNumeric(int count)
Characters will be chosen from the set of numeric characters.
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextNumeric(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of \p{Digit} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generatepublic String nextPrint(int count)
Characters will be chosen from the set of characters which match the POSIX [:print:] regular expression character class. This class includes all visible ASCII characters and spaces (i.e. anything except control characters).
count - the length of random string to createIllegalArgumentException - if count < 0.public String nextPrint(int minLengthInclusive, int maxLengthExclusive)
Characters will be chosen from the set of \p{Print} characters.
minLengthInclusive - the inclusive minimum length of the string to generatemaxLengthExclusive - the exclusive maximum length of the string to generateCopyright © 2001–2025 The Apache Software Foundation. All rights reserved.