[FIXED] Add "-" to a random string

Issue

I want to generate a random String from 9 always separating 3 String with "-"

It must give this at the end: XXX-XXX-XXX

So far I have managed to create a Random of 9 but I don't know how to do the rest

map.put("referCode", getRandomCode(9));

public static String getRandomCode(int i) {
    final String characters = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";
    StringBuilder result = new StringBuilder();
    while (i > 0) {
        Random random = new Random(); 
        result.append(characters.charAt(random.nextInt(characters.length())));
        i++;
    }
    return result.toString();
}

Solution

Here you are, this algorithm is universal. It will work for every value, not only for 9 characters.

public class Algorithm {

    private static final String CHARACTERS = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";
    
    public static void main(String[] args) {
        System.out.println(getRandomCode(9));
        System.out.println(getRandomCode(12));
        System.out.println(getRandomCode(15));
        System.out.println(getRandomCode(50));
    }
 
    public static String getRandomCode(int numberOfCharacters) {
        StringBuilder result = new StringBuilder();
        Random random = new Random();
        for (int index = 1; index <= numberOfCharacters; index++) {
            result.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
            if (index % 3 == 0 && index != numberOfCharacters) {
                result.append("-");
            }
        }
        return result.toString();
    }
} 

It will print:

8PJ-Y6T-4LV
FE7-WRY-64A-2L2
23H-A24-CBF-E8Z-NHD
DXA-8Z3-DB4-2ZS-U2O-SQS-CAR-Y5Z-UXT-AP9-3TI-9ZO-D7T-OMZ-RDN-K34-BB

Also if you want to try the same with while loop you can first split string by 3, add results to the list and then join them with String.join:

public static String getRandomCode(int numberOfCharacters) {

        List<String> results = new ArrayList<>();
        StringBuilder result = new StringBuilder();
        Random random = new Random();
        
        int index = 0;
        int prevIndex = 0;
       
        while (index < numberOfCharacters) {
            index++;
            result.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
            if (index % 3 == 0) {
                results.add(result.substring(prevIndex, index));
                prevIndex = index;
            }
        }
        return String.join("-", results);
    }

And if you want to be super elastic you can also parametrize split point, so not only by 3, but also any other value:

private static final String CHARACTERS = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";

    public static void main(String[] args) {
        System.out.println(getRandomCode(9,3));
        System.out.println(getRandomCode(12,4));
        System.out.println(getRandomCode(15,5));
        System.out.println(getRandomCode(150,50));
    }

    public static String getRandomCode(int numberOfCharacters, int splitPointIndex) {

        List<String> results = new ArrayList<>();
        StringBuilder result = new StringBuilder();
        Random random = new Random();

        int index = 0;
        int prevIndex = 0;

        while (index < numberOfCharacters) {
            index++;
            result.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
            if (index % splitPointIndex == 0) {
                results.add(result.substring(prevIndex, index));
                prevIndex = index;
            }
        }
        return String.join("-", results);
    }

It will print:

HBZ-BWT-MYI
7YSM-DD0K-HJYF
EUQ2P-NFJ4F-L4MRP
MG91WG9F9HF1GM0UH6I91VX7TLNIUDPQUCUK8SXDQ3T087JPAE-JJ6IZHKH2YBZBJKPPHJFR43112JKQDBJ9LSTAA7BTB6O3JXTYX-EGCJBGWJBZJOGBMVCH9TLCL9VSV3L15JR7QZIKIKOZGAOKR6GT

Cheers!

Answered By - MrFisherman