How to properly copy and object

Question

I have an object that I want to keep immutable, I want to provide a copy() method so that it returns a new instance of the Object its copying. But I wanted to know, just for clarity sake, if I did this:
public MyClass copy() {
  MyClass copy = new MyClass();
  copy.byteProperty = this.byteProperty;
  return copy;
}And please note that byteProperty in this case is a byte[].
Is the reference to the copy's byteProperty array a copy of the originals or a reference to it?
I would never ever want the user of my class to be able to change the byteProperty of both the class they copied and the new copy by accident.
For example, would doing this:
MyClass orig = new MyClass(someByteArray);
MyClass copy = orig.copy();
copy.methodToChangeInternals(); //this could internally change around the byte[]would the call to methodToChangeInternals() change the byte[] in both instances?
Thanks!

Answer 1

Encephalopathic wrote:
better than asking this question: test it out for yourself. You get the answer in several ways, by reading and by doing. There's no doubt in my mind that by doing this, you learn more and have a deeper understanding.You are right, and so I did...
I learnt what flounder mentioned, so I implemented by copy() method differently. Using the ArrayUtils.clone() method, I made a clone of the internal state, whic worked fine.
I then read ejp's post, and changed my class to implement Cloneable... and changed the method to clone()
Thanks for the help guys! Very fast turn around :)