Example hashing using bytes

HashingExample.java

class HashingFun {

    public static void main(String[] args) throws NoSuchAlgorithmException {
        MessageDigest hasher = MessageDigest.getInstance("SHA-256");
        long count = 0;
        Random random = new Random();

        byte[] data = new byte[258 / 8];

        while (true) {
            random.nextBytes(data);
            byte[] output = hasher.digest(data);
            count++;
            // one byte is 2 zeros

            if (output[0] == 0 && output[1] == 0 /*&& output[2] == 0*/) {
                System.out.println("Input : " + bytesToString(data));
                System.out.println("Output: " + bytesToString(output));
                System.out.println("Count: " + count);
                return;
            }
        }
    }

    private static String bytesToString(byte[] input) {
        StringBuilder output = new StringBuilder();
        for (byte b : input) {
            String str = Integer.toHexString(b & 0xFF);
            if (str.length() == 1) {
                str = "0" + str;
            }
            output.append(str);
        }
        return output.toString();
    }

    private static byte[] fromHexString(String input) {
        ByteArrayOutputStream output = new ByteArrayOutputStream();

        for (int i = 0; i < input.length(); i += 2) {
            int readByte = Integer.parseInt(input.substring(i, i + 2), 16);
            output.write(readByte & 0xFF);
        }

        return output.toByteArray();
    }
}