public class Sample4 {
    
    public static void main(String[] args) {
        MobilePhone phone = new MobilePhone("PPP");
        phone.feature();
        
        Tablet tablet = new Tablet("QQQ");
        tablet.feature();
        
        MobileDevice device;
        
        device = phone;
        device.feature();
        
        device = tablet;
        device.feature();
        
        Tablet tablet1 = (Tablet)device;
        System.out.println(tablet1.getName());
    }
}