SHA512 in C # and Java are different

There is such code on C # and java, sha512 in them differs, whether it is possible to make somehow that the result sha512 was identical? I understand the problem in BaseConverter, analog Base64 in Java? Tried

Base64.getEncoder().encodeToString(str);

But I get an error because of getEncoder(). Do I need a library for this?

Code in C#:

public string Hash(string str)
{
      string resultStr = String.Empty;
      byte[] data = new UTF8Encoding().GetBytes(str);
      byte[] result;

      SHA512 shaM = new SHA512Managed();
      result = shaM.ComputeHash(data);
      resultStr = ReverseString(BitConverter.ToString(result).ToLower().Replace("-", String.Empty));

      return resultStr.Substring(5, 25);
}       

public static string ReverseString(string s)
{
      char[] charArray = s.ToCharArray();
      Array.Reverse(charArray);
      return new string(charArray);
}

Code in Java:

public String Hash(String str) {
    try {
        MessageDigest digest = MessageDigest.getInstance("SHA-512");
        digest.update(str.getBytes("UTF-16LE"));
        byte messageDigest[] = digest.digest();
        StringBuffer hexString = new StringBuffer();
        for (int i = 0; i < messageDigest.length; i++) {
            String h = Integer.toHexString(0xFF & messageDigest[i]);
            while (h.length() < 2)
                h = "0" + h;
            hexString.append(h);
        }
        result = hexString.toString().toLowerCase();

    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }

    return ReverseString(result).substring(5, 25);
}

 public static String ReverseString(String s)
    {
        return new StringBuilder(s).reverse().toString();
    }