public class KasirPerpus {
    public static void main(String[] args) {
        Buku buku = new Buku("Belajar Java", "BK-001", 80000.0);

        System.out.println("judul        : " + buku.judul);
        System.out.println("kodeInternal : " + buku.kodeInternal);
        System.out.println("label        : " + buku.labelInternal());
        System.out.printf("harga jual   : Rp%.2f%n", buku.hargaJual());
    }
}