Java基础 8.4

1.面向对象练习

package com.logic.homework;

//要求:(1)在上面类的基础上扩展新类CheckingAccount对每次存款和取款都收取1美元的手续费
//(2)扩展前一个练习的BankAccount类，新类SavingsAccount每个月都有利息产生(earnMonthlyInterest方法被调用)
// ，并且有每月三次免手续费的存款或取款。在earnMonthlyInterest方法中重置交易计数
// (3)体会重写的好处
public class Homework08 {
    public static void main(String[] args) {
        CheckingAccount checkingAccount = new CheckingAccount(1000);
        checkingAccount.deposit(10);
        checkingAccount.withdraw(20);
        System.out.println(checkingAccount.getBalance());

        //测试SavingsAccount
        SavingsAccount savingsAccount = new SavingsAccount(1000);
        savingsAccount.deposit(100);
        savingsAccount.deposit(100);
        savingsAccount.deposit(100);
        System.out.println(savingsAccount.getBalance());
        savingsAccount.deposit(100);
        System.out.println(savingsAccount.getBalance());

        //月初，定时器自动调用一下earnMonthlyInterest方法
        savingsAccount.earnMonthlyInterest();
        System.out.println(savingsAccount.getBalance());
        savingsAccount.deposit(1000);
        savingsAccount.deposit(1000);
        savingsAccount.deposit(1000);
        savingsAccount.deposit(1000);
        System.out.println(savingsAccount.getBalance());
    }
}

class BankAccount {
    private double balance;

    public BankAccount(double initialBalance) {
        this.balance = initialBalance;
    }

    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        balance -= amount;
    }

    public double getBalance() {
        return balance;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }
}

package com.logic.homework;

public class SavingsAccount extends BankAccount {
    private int count = 3;
    private double rate = 0.01;

    public SavingsAccount(double initialBalance) {
        super(initialBalance);
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public double getRate() {
        return rate;
    }

    public void setRate(double rate) {
        this.rate = rate;
    }

    @Override
    public void deposit(double amount) {
        if (count > 0) {
            super.deposit(amount);
        } else {
            super.deposit(amount - 1);
        }
        count--;
    }

    @Override
    public void withdraw(double amount) {
        if (count > 0) {
            super.withdraw(amount);
        } else {
            super.withdraw((amount + 1));
        }
        count--;
    }

    public void earnMonthlyInterest() {
        count = 3;
        super.deposit(getBalance() * rate);
    }
}

package com.logic.homework;

public class CheckingAccount extends BankAccount {

    public CheckingAccount(double initialBalance) {
        super(initialBalance);
    }

    @Override
    public void deposit(double amount) {
        super.deposit(amount - 1);//巧妙地使用了父类地deposit方法
        //1元转入银行账号
    }

    @Override
    public void withdraw(double amount) {
        super.withdraw(amount + 1);
        //1元转入银行账号
    }
}