【Java】【继承和多态实例——银行账户】

心已赠人 2022-02-17 06:17 380阅读 0赞

### 题目要求： ###

设计一个名为Account的类，包括：

一个名为id的int型私有账户数据域，默认值0

一个名为balance的double型私有账户数据域，默认值0

一个名为annualInterestRate的double型私有数据域存储当前利率，默认值0，假定所有用户都有相同的利率

一个名为dateCreated的Date型私有数据域存储账户的开户日期

一个能创建默认账户的无参构造方法

一个能带特定id的初始余额账户的构造方法

id, balance和annualInterestRate的访问器和修改器

一个名为getMonthlyInterestRate的方法返回月利率

一个名为withDraw的方法从账户提取特定数额

一个名为deposit的方法向账户存储特定数额

\*\*\*在上述基础上，对于Account类：

添加一个String类型的新数据域name来存储用户的名字

添加一个新的构造方法，该方法创建一个带制定名字，id和收支额的账户

添加一个名为transactions的新数据域，类型为ArrayList，可以为账户存储交易。每笔交易都是一个Transaction类的实例。

修改withDraw和deposit方法，向transaction线性数组表添加一笔交易

### 测试用例： ###

创建一个名为"DXH924"，id为1122，初始余额为20000的账户

设置年利率为4.5%

取款5000

存款3000

并输出所有的交易明细

import java.util.*;
    class Account{
    	private String name = null;
    	private int id;
    	private double balance;
    	private static double annualInterestRate = 0;
    	private Date dateCreated;
    	ArrayList<Transactions> transaction = new ArrayList<Transactions>();
    	public Account(String name, int id, double balance) {
    		this.name = name;
    		this.id = id;
    		this.balance = balance;
    		dateCreated = new Date();
    	}
    	public Account() {
    		this(null, 0, 0);
    	}
    	public void withDraw(double wd) {
    		if (wd > balance) {
    			System.out.println("余额不足，提款失败！");
    		} else {
    			balance -= wd;
    			String des = "已成功取出: " + wd + "元，当前余额: " + balance + "元";
    			transaction.add(new Transactions('W', wd, balance, des));
    		}
    	}
    	public void deposit(double dp) {
    		balance += dp;
    		String des = "已成功存入: " + dp + "元，当前余额: " + balance + "元";
    		transaction.add(new Transactions('D', dp, balance, des));
    	}
    	public void setAnnualInterestRate(double rate) {
    		annualInterestRate = rate;
    	}
    	
    	public String getName() {
    		return name;
    	}
    	public Date getDateCreated() {
    		return dateCreated;
    	}
    	public double getBalance() {
    		return balance;
    	}
    	public double getMonthlyInterestRate() {
    		return annualInterestRate / 12;
    	}
    	public double getMonthlyInterest() {
    		return balance * annualInterestRate / 12 ;
    	}
    	public String showInfo() {
    		return "用户名：\t\t" + getName() + "\n"
    		+ "余额：\t\t" + getBalance() + "\n"
    		+ "月利息：\t\t" + getMonthlyInterest() + "\n"
    		+ "开户日期：\t" +getDateCreated() + "\n";
    	}
    }
    class Transactions {
    	private Date date;
    	private char type; // D: deposit, W: withdraw
    	private double amount;
    	private double balance;
    	private String description;
    	public Transactions(char type, double amount, double balance, String description) {
    		date = new Date();
    		this.type = type;
    		this.amount = amount;
    		this.balance = balance;
    		this.description = description;
    	}
    	public String getDescription() {
    		return description;
    	}
    	public String getTransaction() {
    		return "交易时间：\t" + date + "\n"
    		+ "交易类型：\t" + type + "\n" 
    		+ "余额：\t\t" + balance + "\n";
    	}
    	public void showInfo() {
    		System.out.println(getTransaction());
    	}
    }
    public class Test{
    	public static void main(String args[]) {
    		Account a = new Account("DXH924", 1122, 20000);
    		a.setAnnualInterestRate(0.0045);
    		a.withDraw(5000);
    		a.deposit(3000);
    		System.out.println(a.showInfo());
    		for (int i=0; i<a.transaction.size(); i++) {
    			a.transaction.get(i).showInfo();
    		}
    	}
    }

### 测试结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RYSDkyNA_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RYSDkyNA_size_16_color_FFFFFF_t_70]: /images/20220217/922b881b311444a7aed1d5caf922fdac.png