try {
FileOutputStream fos = new FileOutputStream("test");
MessageDigest md = MessageDigest.getInstance("SHA");
ObjectOutputStream oos = new ObjectOutputStream(fos);
String data = "This have I thought good to deliver thee, " +
"that thou mightst not lose the dues of rejoicing " +
"by being ignorant of what greatness is promised thee.";
byte buf[] = data.getBytes();
md.update(buf);
oos.writeObject(data);
oos.writeObject(md.digest());
} catch (Exception e) {
System.out.println(e);
}