How to generate a random alpha-numeric string

To generate a random alpha-numeric string in Java, you can use the Random class and the nextInt and nextBoolean methods to generate random characters and append them to a StringBuilder. Here's an example of how you might do this:

// Set the length of the string
int length = 10;

// Create a StringBuilder to store the string
StringBuilder sb = new StringBuilder();

// Create a Random object
Random random = new Random();

// Generate random characters and append them to the StringBuilder
for (int i = 0; i < length; i++) {
  // Generate a random integer between 0 and 9
  int number = random.nextInt(10);
  // Append the integer to the StringBuilder
  // Generate a random boolean value
  boolean isLowerCase = random.nextBoolean();
  // If the boolean is true, append a random lowercase letter to the StringBuilder
  if (isLowerCase) {
    char letter = (char)(random.nextInt(26) + 'a');
  // If the boolean is false, append a random uppercase letter to the StringBuilder
  else {
    char letter = (char)(random.nextInt(26) + 'A');

// Convert the StringBuilder to a String and print it
String randomString = sb.toString();

This code will generate a random string that is 10 characters long and consists of a combination of digits (0-9) and letters (a-z or A-Z).

I hope this helps! Let me know if you have any other questions.