File folder = new File(dir + "/");//contains anything from 1-20 pictures
File[] allPics = folder.listFiles();

private Bitmap[] thumbnails;
private String[] arrPath;

//load all the files into bitmaps to assign to my gridview adapter
for (int i = 0; i < allPics.length; i++) {
            thumbnails[i] = BitmapFactory.decodeFile(allPics[i].getAbsolutePath());//where the exception is thrown

            arrPath[i]= allPics[i].getAbsolutePath();
        }