How to generate a random string, and specify the length you want, or better generate unique string on specification you want

Question

There is a library to generate Random numbers, so why isn\'t there a library for generation of random strings?

In other words how to generate a random string, and sp

Answer 1

public  static String getAlphaNumericString(int n) {

        String AlphaNumericString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "0123456789" + "abcdefghijklmnopqrstuvxyz";

        StringBuilder sb = new StringBuilder(n);

        for (int i = 0; i < n; i++) {

            // generate a random number between
            // 0 to AlphaNumericString variable length
            int index = (int) (AlphaNumericString.length() * Math.random());

            // add Character one by one in end of sb
            sb.append(AlphaNumericString.charAt(index));
        }

        return sb.toString();
    }