public static ISpriteSheet houses = new ISpriteSheet("/res/houses.png", 56, 71);

private SpriteSheet sheet;

public ISpriteSheet(String path, int width, int height) {
    try {
        sheet = new SpriteSheet(path, width, height);
    } catch (SlickException e) {
        e.printStackTrace();
    }
}

public Image getSubImage(int x, int y) {
    return sheet.getSubImage(x, y);
}