Question

How to generate random string without repetition in Java

Answer 1

import java.util.Collections;
import java.util.ArrayList;
import java.util.Random;
import java.util.List;

public class RandomString {
   public static String generate_rand_string_without_repetition_(int size) {
        final String characters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        
        List<Character> charList = new ArrayList<Character>();
        
        for (char ch : characters.toCharArray()) {
            charList.add(ch);
        }
        
        Collections.shuffle(charList, new Random());

        StringBuilder rand_string = new StringBuilder();
        for (int i = 0; i < size; i++) {
            rand_string.append(charList.get(i));
        }
        
        return rand_string.toString();
  }

  public static void main(String[] args) {
    int length = 15;
    
    String randomString = generate_rand_string_without_repetition_(length);
    
    System.out.println(randomString);
  }
}



/*
run:

Mz7Rnx50GilrJtD

*/

 

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