SHA -256 Hash in Java Spring boot

package com.javaskool;

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
// Java program to calculate SHA hash value
 
class GenerateSHA256InSpringBoot {
    public static byte[] getSHA(String input) throws NoSuchAlgorithmException
    {
        // Static getInstance method is called with hashing SHA
        MessageDigest md = MessageDigest.getInstance("SHA-256");
 
        // digest() method called
        // to calculate message digest of an input
        // and return array of byte
        return md.digest(input.getBytes(StandardCharsets.UTF_8));
    }
     
    public static String toHexString(byte[] hash)
    {
        // Convert byte array into signum representation
		/*
		 * Translates the sign-magnitude representation of a BigInteger into
		 * aBigInteger. The sign is represented as an integer signum value: -1
		 * fornegative, 0 for zero, or 1 for positive. The magnitude is a byte arrayin
		 * big-endian byte-order: the most significant byte is in the zeroth element. A
		 * zero-length magnitude array is permissible, and willresult in a BigInteger
		 * value of 0, whether signum is -1, 0 or 1
		 */

        BigInteger number = new BigInteger(1, hash);
 
        // Convert message digest into hex value
        StringBuilder hexString = new StringBuilder(number.toString(16));
 
        // Pad with leading zeros
        while (hexString.length() < 64)
        {
            hexString.insert(0, '0');
        }
 
        return hexString.toString();
    }
 
    // Driver code
    public static void main(String args[])
    {
        try
        {
            System.out.println("HashCode Generated by SHA-256 for:");       
 
            String s2 = "hello world";
            System.out.println("\n" + s2 + " : " + toHexString(getSHA(s2)));
            
            String s1 = "Javaskool.com";
            System.out.println("\n" + s1 + " : " + toHexString(getSHA(s1)));
             
            String s3 = "James Bond"; 
            System.out.println("\n" + s3 + " : " + toHexString(getSHA(s3)));
        }        
        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown for incorrect algorithm: " + e);
        }
    }
}