SHA256Helper.java

package blockchain;

import java.security.MessageDigest;

public class SHA256Helper {
    public static String hash(String data){
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hash = digest.digest(data.getBytes("UTF-8"));

            // TO Hexadecimal value.
            StringBuffer hexadecimalString = new StringBuffer();

            for (int i = 0; i <hash.length ; i++) {
                String hexadecimal = Integer.toHexString(0xff & hash[i]);
                if (hexadecimal.length() == 1){
                    hexadecimalString.append('0');
                }hexadecimalString.append(hexadecimal);
            }
            return hexadecimalString.toString();
        }catch (Exception e){
            throw new RuntimeException(e);
        }
    }
}