Introduction to Java - Abstract Class Case

case:

A gas station launched two types of payment cards, one is a gold card with 10,000 pre-stored, and enjoys a 20% discount on subsequent refueling, and the other is a silver card with a pre-deposited 5,000, and enjoys a 15% discount on subsequent refueling.
Please implement the logic after the two cards enter the cash register system. The cards need to contain the owner's name, balance, and payment functions.

1. Create a parent class Card:

public abstract class Card {
    private String userName;
    private double money;//卡片的余额

    /**
     *定义一个支付方法，表示卡片可以支付
     * 因为每张卡片的支付方式不一样，所以不能在父类中定死，
     * 但每张卡片都要执行支付功能且支付行为不一样，所以把支付手段定义为子类中的约定手段，使用抽象方法
     * nomey:代表消费的余额。
     */
    public abstract void pay(double nomey);

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }
}

2. Create subclasses, gold card users and silver card users:

//金卡用户
public class GoldCard extends Card {
    @Override
    public void pay(double money02) {
        System.out.println("尊贵的金卡会员，您好。");
        System.out.println("您当前消费:" + money02 );
        System.out.println("您的卡片当前余额是:" + getMoney());
        //优惠价
        double rs = money02 * 0.8;
        System.out.println(getUserName() + "您实际消费为:" + rs);
        //更新账户余额,这里假设他当前余额大于消费余额
        setMoney(getMoney() - rs);
    }
}

//银卡用户
public class SilverCard extends Card{
    @Override
    public void pay(double money02) {
        System.out.println("尊贵的银卡卡会员，您好。");
        System.out.println("您当前消费:" + money02 );
        System.out.println("您的卡片当前余额是:" + getMoney());
        //优惠价
        double rs = money02 * 0.85;
        System.out.println(getUserName() + "您实际消费为:" + rs);
        //更新账户余额,这里假设他当前余额大于消费余额
        setMoney(getMoney() - rs);
    }
}

3. Use an abstract class:

public class Demo {
    public static void main(String[] args) {
        //学习抽象类的基本使用:做父类，被继承，重写抽象方法
        GoldCard c = new GoldCard();
        c.setMoney(10000);
        c.setUserName("qing");
        c.pay(300);
        System.out.println("剩余:" + c.getMoney());

        SilverCard c1 = new SilverCard();
        c1.setMoney(10000);
        c1.setUserName("chen");
        c1.pay(300);
        System.out.println("剩余:" + c1.getMoney());
    }
}

Introduction to Java - Abstract Class Case

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