Why have the boolean array at all? The technique only makes sense if
upper is very large compared with count, so that the collision risk is
very low, and in that case it is bad to have to create an array with
upper elements. Here's a simplified, though still untested, version.

 package testit;
 import java.util.Random;
 import java.util.Set;
 import java.util.HashSet;

 public class Scrambler
 {
  private final Random rand = new Random();

  public Set <Integer> scrambleEggs( int upper, int count )
  {
    Set <Integer> chosen = new HashSet <Integer> ( count * 4 / 3 + 1 );

    while ( chosen.size() < count )
    {
      chosen.add(Integer.valueOf(rand.nextInt( upper ));
    }
    return chosen;
  }
 }

Testing chosen.size(), rather than counting add attempts, automatically
deals with duplicates, because adding a duplicate does not increase the
size of the Set.

Patricia

thank you all very  much for yr responses.. actually I decided that
instead of displaying the images at random in server (which means every
time user comes back photos would be displayed in a different order, I'm
not sure I want that) I want do do the following:

when photos first come in from memory card they are named thus:

DSC_0001.JPG, DSC_0002.JPG, DSC_0003.JPG, etc...

so instead of dislaying images at random in actual site I want to use
random function when RENAMING images (locally, w/stand-alone class)
before uploading them.. now I have written a class for this, thus:

import java.io.*;

public class Rename {

    public static void main(String[] args) {

    int posDot;
    String _temp = "";
    String no = "";

    // if no arg passed start naming of imgs @ "1"
    // else start at whatever no. is passed to class...
    if (null == args || args.length < 1) {
      no = "1";
     } else {
       no = args[0];
     }
    int iNo = Integer.parseInt(no);

        File directory = new File(System.getProperty("user.dir"));
        String[] textFileNames = directory.list(new FilenameFilter() {
             public boolean accept(File dir, String name) {
                   return name.endsWith(".JPG");
                    }
                });

    for (int j=0; j < textFileNames.length+1; j++) {
    //  System.out.print(textFileNames[j] + "\n");
    }

        for (int i = 0; i < textFileNames.length; ++i) {
            File oldFile = new File(textFileNames[i]);
      posDot = textFileNames[i].indexOf(".");
      _temp = textFileNames[i].substring(0,posDot);
    //  System.out.print(_temp + "\n");
      File newFile = new File(i+iNo +  ".jpg");
            oldFile.renameTo(newFile);
       }
  }
}

(adapted from example I found here:
http://www.zanthan.com/itymbi/archives/000805.html)

I would like to use random function to rename imgs at random (i.e., so
instead of 1.jpg, 2.jpg, etc, in same order as orig's ones, I would like
to do, say, name first img a number, 2nd image another number, but at
random.. )
(reason sometimes I'll need to start renaming at @ no. diff from "1" is
that in each dir I have imgs from one mem. card, and thus can have one
img named DSC_0002.JPG in two diff folders b/c they came from diff
cards, so can't just put all imgs from all cards in one folder..  so,
after renaming, will have in 1st folder 1.jpg, etc.. thru, say, 15.jpg,
then in second folder need to start at 16.jpg.. etc..   and if I want to
shuffle among all imgs (not just imgs in one folder) I need to do this..
  I hope this makes sense..)

thank you very much..

ok, I think got Collections.shuffle() part..

   Collections.shuffle(photos, new Random());

only problem now is how to add all nos. to ArrayList (this has to be 1.4
construction, not 1.5..)

and then how to go from Collections.shuffle to this:

for (int i = 0; i < textFileNames.length; ++i) {
  File oldFile = new File(textFileNames[i]);
  posDot = textFileNames[i].indexOf(".");
  _temp = textFileNames[i].substring(0,posDot);
  File newFile = new File(i+1 +  ".jpg");
  oldFile.renameTo(newFile);
}

so imgs are named with nos. at random (i.e., so imgs, after renamed, are
in diff order from orig ones..)

thank you....