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## org.apache.commons.lang
Class RandomStringUtils

    java.lang.Object
      org.apache.commons.lang.RandomStringUtils

    public class RandomStringUtils

extends Object

Operations for random `String`s.

Currently 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.

Since:
  1.0
Version:
  $Id: RandomStringUtils.java 905636 2010-02-02 14:03:32Z niallp $
Author:
  Apache Software Foundation, Steven Caswell, Gary Gregory, Phil Steitz

Constructor Summary
`RandomStringUtils()` `RandomStringUtils` instances should NOT be constructed in standard programming.

Method Summary
`static String` | `random(int count)` Creates a random string whose length is the number of characters specified.
`static String` | `random(int count, boolean letters, boolean numbers)` Creates a random string whose length is the number of characters specified.
`static String` | `random(int count, char[] chars)` Creates a random string whose length is the number of characters specified.
`static String` | `random(int count, int start, int end, boolean letters, boolean numbers)` Creates a random string whose length is the number of characters specified.
`static String` | `random(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.
`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)` Creates a random string whose length is the number of characters specified.
`static String` | `randomAlphabetic(int count)` Creates a random string whose length is the number of characters specified.
`static String` | `randomAlphanumeric(int count)` Creates a random string whose length is the number of characters specified.
`static String` | `randomAscii(int count)` Creates a random string whose length is the number of characters specified.
`static String` | `randomNumeric(int count)` Creates a random string whose length is the number of characters specified.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### RandomStringUtils

    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.

Method Detail

### random

    public static String random(int count)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of all characters.

  Parameters:
    `count` - the length of random string to create
  Returns:
    the random string

### randomAscii

    public static String randomAscii(int count)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of characters whose ASCII value is between `32` and `126` (inclusive).

  Parameters:
    `count` - the length of random string to create
  Returns:
    the random string

### randomAlphabetic

    public static String randomAlphabetic(int count)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of alphabetic characters.

  Parameters:
    `count` - the length of random string to create
  Returns:
    the random string

### randomAlphanumeric

    public static String randomAlphanumeric(int count)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of alpha-numeric characters.

  Parameters:
    `count` - the length of random string to create
  Returns:
    the random string

### randomNumeric

    public static String randomNumeric(int count)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of numeric characters.

  Parameters:
    `count` - the length of random string to create
  Returns:
    the random string

### random

    public static String random(int count,
                                boolean letters,
                                boolean numbers)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.

  Parameters:
    `count` - the length of random string to create
    `letters` - if `true`, generated string will include alphabetic characters
    `numbers` - if `true`, generated string will include numeric characters
  Returns:
    the random string

### random

    public static String random(int count,
                                int start,
                                int end,
                                boolean letters,
                                boolean numbers)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.

  Parameters:
    `count` - the length of random string to create
    `start` - the position in set of chars to start at
    `end` - the position in set of chars to end before
    `letters` - if `true`, generated string will include alphabetic characters
    `numbers` - if `true`, generated string will include numeric characters
  Returns:
    the random string

### random

    public static String random(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.

  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.

  Parameters:
    `count` - the length of random string to create
    `start` - the position in set of chars to start at
    `end` - the position in set of chars to end before
    `letters` - only allow letters?
    `numbers` - only allow numbers?
    `chars` - the set of chars to choose randoms from. If `null`, then it will use the set of all chars.
  Returns:
    the random string
  Throws:
    `ArrayIndexOutOfBoundsException` - if there are not `(end - start) + 1` characters in the set array.

### random

    public 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.

  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 `Integer.MAX_VALUE`.

  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.

  Parameters:
    `count` - the length of random string to create
    `start` - the position in set of chars to start at
    `end` - the position in set of chars to end before
    `letters` - only allow letters?
    `numbers` - only allow numbers?
    `chars` - the set of chars to choose randoms from. If `null`, then it will use the set of all chars.
    `random` - a source of randomness.
  Returns:
    the random string
  Throws:
    `ArrayIndexOutOfBoundsException` - if there are not `(end - start) + 1` characters in the set array.
    `IllegalArgumentException` - if `count` < 0.
  Since:
    2.0

### random

    public static String random(int count,
                                String chars)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of characters specified.

  Parameters:
    `count` - the length of random string to create
    `chars` - the String containing the set of characters to use, may be null
  Returns:
    the random string
  Throws:
    `IllegalArgumentException` - if `count` < 0.

### random

    public static String random(int count,
                                char[] chars)

  Creates a random string whose length is the number of characters specified.

  Characters will be chosen from the set of characters specified.

  Parameters:
    `count` - the length of random string to create
    `chars` - the character array containing the set of characters to use, may be null
  Returns:
    the random string
  Throws:
    `IllegalArgumentException` - if `count` < 0.

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