Question

How to generate a random alpha-numeric string in Java

Answer 1

import java.util.Random;
 
public class MyClass {
    public static String GenerateRandomString(int length) {
        StringBuilder sb = new StringBuilder();
         
        Random random = new Random();
         
        for (int i = 0; i < length; i++) {
          boolean isLowerCase = random.nextBoolean();
           
          if (isLowerCase) {
                int number = random.nextInt(10);
                sb.append(number);
                char ch = (char)(random.nextInt(26) + 'a');
                sb.append(ch);
                i++;
          } 
          else {
                char ch = (char)(random.nextInt(26) + 'A');
                sb.append(ch);
          }
        }
         
        return sb.toString();
    }
    public static void main(String args[]) {
        String randomString = GenerateRandomString(10);
 
        System.out.println(randomString);
    }
}
 
 
 
 
/*
run:
 
WA4y6hU0eY
 
*/

 

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Answer 2

import java.util.Random;

public class MyClass {
    public static String GenerateRandomString(int len) {
        String chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
           
        Random rnd = new Random();
        StringBuilder sb = new StringBuilder(len);
        
        for (int i = 0; i < len; i++)
            sb.append(chars.charAt(rnd.nextInt(chars.length())));
           
        return sb.toString();
    }
    public static void main(String args[]) {
        String randomString = GenerateRandomString(10);

        System.out.println(randomString);
    }
}




/*
run:

LsL7j0OHar

*/

 

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