Simple string / bytes problem

Question

Hi
I'm basically trying to simulate DES in java from scratch (so no use of existing API's or anything). I've got a basic idea of how DES works (use of a feistel cipher).
So to start off I'm trying to get the bytes of a string with this simple program:
public class Test {
     public static void main(String[] args) {     
          String testString = "hello";
          System.out.println(testString.getBytes());
}The output consists of some characters (namely numbers, letters and 1 special character).
But when I change the variable testString to some other String, complie and run I still get the same output even though the String is different. Also why are there 9 characters for a String thats only 5 characters long?
Thanks

Answer 1

When you use System.out.println( something ) it uses to the toString() method of the object referenced by 'something'. When the something is an array such as an array of bytes the toString() methed returns a pseudo reference to the array which in no way reflects the content of the array.
If you just want to see the content of the array then use Arrays.toString(something) to generate a String representation of the content of the array.
Also, the use of String.getBytes() will convert the String to bytes using your default character encoding. This is rarely what you want since the result may depend on which platform you are working on. In my view, the safest and best approach is to explicitly define the encoding and since it will encode ALL characters one can throw at it I always use utf-8. So, to convert a String to bytes I would usebyte[] bytesOfString = "your string".getBytes("utf-8");and to convert them back to a String I would useString yourString = new String(bytesOfString,"utf-8");One final point, do not assume that an apparently random array of bytes such as one gets from DES encryption can be converted to a String using the above. In general it can't because not all bytes and byte sequences are valid for a particular character encoding. If you absolutely have to have a String representation then you should encode (not encrypt) the bytes using something like Base64 or Hex encoding.
Edited by: sabre150 on Jan 27, 2008 3:04 PM