message digest technique MD5 algorithm

package create.digest;
import java.io.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.*;
public class CreateDigest {
    public static void main(String[] args)throws FileNotFoundException{
        try{
            FileOutputStream fos = new FileOutputStream("sample.txt");
            MessageDigest md= MessageDigest.getInstance("MD5");
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            String data = "I am ashish";
            byte buffer []=data.getBytes();
            System.out.println("buffer:-"+buffer);
            md.update(buffer);
            oos.writeObject(data);
            oos.writeObject(md.digest());
            System.out.println("Message Digest"+md);
            System.out.println("Data:-"+data);
            System.out.println("Digest:-"+(md.digest()).toString());
            System.out.println("Done...!");
        }catch(Exception e){
            e.printStackTrace();
        }  
    }
}



output:
run:
buffer:-[B@a88bc2
Message DigestMD5 Message Digest from SUN, <initialized>

Data:-I am ashish
Digest:-[B@17d7c01
Done...!

BUILD SUCCESSFUL (total time: 7 seconds)