public class Images extends Activity {
    // Get list of files from SD card
    public static String dir = Environment.getExternalStorageDirectory()+"/DCIM/Camera/";
    File fileList = new File(dir);
        File[] filenames = fileList.listFiles(new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            return name.toLowerCase().endsWith(".jpg");
        }
    });
        private static List<String> pathsList = new ArrayList<String>();
        for(final File f : filenames) {
                imageList.add(f.getAbsolutePath());
                }
        
    // Get image list inside the final and static imageUrls
        public final static String[] imageUrls = new String[ imageList.size() ];
        imageList.toArray( imageUrls );
    //...