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?
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() < 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.
char[] given that you know exactly how long it will be. No need to append anything. I'd also use Random.nextInt rather than calling nextFloat and multiplying it by the length.
RandomStringUtils from Apache commons-lang might help:
RandomStringUtils.randomAlphanumeric(17).toUpperCase() 2017 update: RandomStringUtils has been deprecated, you should now use RandomStringGenerator.
RandomStringGenerator in commons-text.
RandomStringUtils.random(length, useLetters, useNumbers) where length is int while useLetters and useNumbers are boolean values.
RandomStringUtils has been replaced/deprecated? I'm just seeing "RandomStringUtils is intended for simple use cases. For more advanced use cases consider using Apache Commons Text's RandomStringGenerator instead." here
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 < length; i ++) { sb.append (candidateChars.charAt (random.nextInt (candidateChars .length ()))); } return sb.toString (); } } 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 < 17; i++) { int randIndex=rand.nextInt(aToZ.length()); res.append(aToZ.charAt(randIndex)); } return res.toString(); } 