Java中的抽象类

举个例子：

父类card.java：

package com.key.d12_packeg.abstractdemo;
public abstract class card {
    private String name;
    private double money;
    public abstract void pay(double moneypay);
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public double getMoney() {
        return money;
    }
    public void setMoney(double money) {
        this.money = money;
    }
}

子类golden.java：

package com.key.d12_packeg.abstractdemo;
public class golden extends card{
    @Override
    public void pay(double moneypay) {
        /*
        金卡优惠
         */
        //优惠后消费金额
        double money_pay = moneypay * 0.8;
        //卡内剩余金额
        double result = getMoney() - money_pay;
        System.out.println("======金卡用户：" + getName() + "======");
        System.out.println("卡内总余额为：" + getMoney());
        System.out.println("本次消费为：" + money_pay);
        System.out.println("当前卡内余额为：" + result);
        System.out.println("==============");
        //对卡内余额进行更新
        setMoney(result);
    }
}

运行Java

package com.key.d12_packeg.abstractdemo;
import java.util.Scanner;
public class testdemo {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        golden golden_card = new golden();
        System.out.println("请输入本次消费的金额：");
        double money = scanner.nextDouble();
        golden_card.setMoney(10000);
        golden_card.setName("金卡用户1");
        golden_card.pay(money);
        System.out.println("****************");
        System.out.println(golden_card.getMoney());
    }
}

抽象类的特征：