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38 answers
Answers
If you want to control the characterset and length take for example
public static String randomString(char[] characterSet, int length) { Random random = new SecureRandom(); char[] result = new char[length]; for (int i = 0; i < result.length; i++) { // picks a random index out of character set > random character int randomCharIndex = random.nextInt(characterSet.length); result[i] = characterSet[randomCharIndex]; } return new String(result); }
and combine with
char[] CHARSET_AZ_09 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
to specify the characterset.
It s not based on StringBuilder since you know the length and don t need all the overhead.
It allocates a char[] array of the correct size, then fills each cell in that array with a randomly chosen character from the input array.
Source
License : cc by-sa 3.0
http://stackoverflow.com/questions/18069434/generating-alphanumeric-random-string-in-java