Add "-" to a random string-CodePudding

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();
}

CodePudding user response：

In addition to the given answers it may be possible to use regular expressions to insert a separator/delimiter between each N characters:

using String::replaceAll:

System.out.println(random.replaceAll("(.{3})(?!$)", "$1-"));

Here negative lookahead is used to detect the end of the string (?!$).

using String.join String.split (see splitting a string at every n-th character):

System.out.println(String.join("-", random.split("(?<=\\G.{3})")));

For the given "random" string:

for (String random : Arrays.asList("12345678", "ABCDEF123456")) {
    System.out.println(random.replaceAll("(.{3})(?!$)", "$1-"));
  
    System.out.println(String.join("-", random.split("(?<=\\G.{3})")));
}

The output is as follows:

123-456-78
123-456-78
ABC-DEF-123-456
ABC-DEF-123-456

CodePudding user response：

You can do something like this:

private static final String CHARACTERS = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";
public static String getRandomCode() {
    StringBuilder result = new StringBuilder();
    Random random = new Random(); 
    for (int i = 0; i < 9; i  ) {
        result.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
        if (i == 2 || i == 5)
            resault.append('-');
    }
    return result.toString();
}

Another option will be to use what you already wrote and do this:

String code = getRandomCode(9);
code = code.substring(0,3)   '-'   code.substring(3,6)   '-'   code.substring(6,9);

for more general case, you can use this:

private static final String CHARACTERS = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";
public static String getRandomCode(int segmentLength, int segmentAmount) {
    StringBuilder result = new StringBuilder();
    Random random = new Random(); 
    for (int i = 0; i < segmentAmount; i  ) {
        if (i != 0)
            resault.append('-');
        for (int j = 0; j < segmentLength; j  )
            result.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
    }
    return result.toString();
}

CodePudding user response：

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!

CodePudding user response：

String randomString = result.toString();
String firstSegment = randomString.substring(0, 3);
String secondSegment = randomString.substring(3, 6);
String thirdSegment = randomString.substring(6, 10);

String finalResult = firstSegment   "-"   secondSegment   "-"   thirdSegment;

return finalResult;

CodePudding user response：

Try this.

static final String CHARACTERS = "ABCDEFGHIJKLMONPQRSTUVWXYZ0123456789";

public static String getRandomCode(int i) {
    return new Random().ints(i, 0, CHARACTERS.length())
        .mapToObj(r -> String.valueOf(CHARACTERS.charAt(r)))
        .collect(Collectors.joining())
        .replaceAll(".{3}(?!$)", "$0-");
}

public static void main(String[] args) {
    System.out.println(getRandomCode(9));
    System.out.println(getRandomCode(10));
}

output:

MHC-ELK-44H
9X8-L2P-UMD-L

CodePudding user response：

If it's always going to have a length of nine, then this can be quite compact.

public static String gen() {
    return String.format("%s-%s-%s", triplet(), triplet(), triplet());
}

private static String triplet() {
    return String.format("%c%c%c", single(), single(), single());
}

private static char single() {
    return (char) ('A'   ThreadLocalRandom.current().nextInt('Z'-'A'   1));
}