Creating a random string with A-Z and 0-9 in Java

Question

As the title suggest I need to create a random  17 characters long  ID  Something like  AJB53JHS232ERO0H1   The order of letters and numbers is also random  I thought of creating an array with letters A-Z and a  check  variable that randoms to 1-2  And in a loop   Randomize  check  to 1-2  If  check    1  then the character is a letter  Pick a random index from the letters array  else Pick a random number    But I feel like there is an easier way of doing this  Is there

User · Answer

Three steps to implement your function   Step 1 You can specify a string  including the chars A-Z and 0-9   Like     String candidateChars    ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890     Step 2 Then if you would like to generate a random char from this candidate string  You can use    candidateChars charAt random nextInt candidateChars length        Step 3 At last  specify the length of random string to be generated  in your description  it is 17    Writer a for-loop and append the random chars generated in step 2 to StringBuilder object   Based on this  here is an example     public class RandomTest    public static void main String   args         System out println generateRandomChars               ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890   17                   param candidateChars               the candidate chars     param length               the number of random chars to be generated         return     public static String generateRandomChars String candidateChars  int length        StringBuilder sb   new StringBuilder        Random random   new Random        for  int i   0  i  lt  length  i              sb append candidateChars charAt random nextInt candidateChars                  length                  return sb toString

User · Answer

You can easily do that with a for loop   public static void main String   args      String aToZ  ABCD     1234      36 letter    String randomStr generateRandom aToZ       private static String generateRandom String aToZ        Random rand new Random        StringBuilder res new StringBuilder        for  int i   0  i  lt  17  i             int randIndex rand nextInt aToZ length             res append aToZ charAt randIndex                          return res toString

User · Answer

Here you can use my method for generating Random String  protected String getSaltString             String SALTCHARS    ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890           StringBuilder salt   new StringBuilder            Random rnd   new Random            while  salt length    lt  18       length of the random string              int index    int   rnd nextFloat     SALTCHARS length                 salt append SALTCHARS charAt index                      String saltStr   salt toString            return saltStr           The above method from my bag using to generate a salt string for login purpose

User · Answer

RandomStringUtils from Apache commons-lang might help   RandomStringUtils randomAlphanumeric 17  toUpperCase       2017 update  RandomStringUtils has been deprecated  you should now use RandomStringGenerator

[java] Creating a random string with A-Z and 0-9 in Java

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