//  Code from Java almanac
    private List<String> getFilesAvailable(String directoryName) {
        File dir = ;
        File[] files = dir.listFiles();
        // This filter only returns directories
        FileFilter fileFilter = new FileFilter() {
            public boolean accept(File file) {
                return file.isDirectory();
            }
        };
        List<String> filesAvailable = new ArrayList<String>();
        //  Assuming this is Java 5
        for (File file: new File(directoryName).listFiles(fileFilter);) {
            if (file.getAbsolutePath().contains("image") && file.getAbsolutePath().contains("what_ever_else_you_want")) {
                filesAvailable.add(file.getAbsolutePath());
            }
        }
        return filesAvailable;
    }
 
    //  This is where you use it
    //  You may want to sort it (not quite sure of the nature of your assignment:
    List<String> myListOfFiles = getFilesAvailable("/image/flag/");
    Collections.sort(myListOfFiles);
    ImageIcon [] images = new ImageIcon[myListOfFiles.size();
    int index = 0;
    for (String myFile : myListOfFiles) { 
        imageIcon[index] = new ImageIcon(myFile);
        index++;
    }