return t.getId();
    public void addTile(Tile t) {        if (t.getId() < 0) {            t.setId(tiles.size());        }        if (t.getId() >= tiles.size()) {            tiles.setSize(t.getId() + 1);        }        tiles.set(t.getId(), t);        //System.out.println("adding tile " +t.getId());        t.setTileSet(this);        t.setStandardHeight(standardHeight);        if (standardWidth < t.getWidth()) {            standardWidth = t.getWidth();        }    }