用Java实现定义Account类的一个子类:NewAccount，它包括： • 添加一个String类型的新数据域name来存储客户的名字 • 添加一个新的构造方法，该方法创建一个具有指定名字、id和余额的账户 • 添加一个名为transactions的ArrayList类型的新数据域，用于存储账户的交易。每笔交易都是一个Transaction类的实例。Transaction类的定义如下图。 • 修改withdraw和deposit方法，向transactions数字列表添加一笔交易。 • 其他属性和方法都和Account类中一样 编写测试程序，创建一个NewAccount的对象，账户name为“Tom”、id为1234、余额为1000美元、年利率为1.5%的Account对象。向该账户存入30美元、40美元和50美元并从该账户取出5美元、4美元和2美元。打印账户清单，显示账户持有者名字、利率、余额和所有的交易。

下面是实现NewAccount类的代码：

import java.util.ArrayList;

public class NewAccount extends Account {
    private String name;
    private ArrayList<Transaction> transactions;

    public NewAccount(String name, int id, double balance) {
        super(id, balance);
        this.name = name;
        transactions = new ArrayList<>();
    }

    public String getName() {
        return name;
    }

    public ArrayList<Transaction> getTransactions() {
        return transactions;
    }

    @Override
    public void withdraw(double amount) {
        super.withdraw(amount);
        transactions.add(new Transaction('W', amount, getBalance(), "Withdraw"));
    }

    @Override
    public void deposit(double amount) {
        super.deposit(amount);
        transactions.add(new Transaction('D', amount, getBalance(), "Deposit"));
    }
}

其中，NewAccount继承自Account类，增加了一个名为name的String类型的数据域和一个名为transactions的ArrayList类型的数据域，表示账户的交易记录。在withdraw和deposit方法中，新增加一笔交易记录，即创建一个Transaction类的实例并添加到transactions中。

下面是Transaction类的代码：

import java.util.Date;

public class Transaction {
    private Date date;
    private char type;
    private double amount;
    private double balance;
    private String description;

    public Transaction(char type, double amount, double balance, String description) {
        date = new Date();
        this.type = type;
        this.amount = amount;
        this.balance = balance;
        this.description = description;
    }

    public Date getDate() {
        return date;
    }

    public char getType() {
        return type;
    }

    public double getAmount() {
        return amount;
    }

    public double getBalance() {
        return balance;
    }

    public String getDescription() {
        return description;
    }
}

最后，我们可以编写测试程序来测试NewAccount类的功能：

public class TestNewAccount {
    public static void main(String[] args) {
        NewAccount account = new NewAccount("Tom", 1234, 1000);
        account.setAnnualInterestRate(1.5);

        account.deposit(30);
        account.deposit(40);
        account.deposit(50);
        account.withdraw(5);
        account.withdraw(4);
        account.withdraw(2);

        System.out.println("Account holder name: " + account.getName());
        System.out.println("Annual interest rate: " + account.getAnnualInterestRate());
        System.out.println("Balance: " + account.getBalance());

        for (Transaction transaction : account.getTransactions()) {
            System.out.println(transaction.getDate() + "\t" + transaction.getType() + "\t" + transaction.getAmount() + "\t" + transaction.getBalance() + "\t" + transaction.getDescription());
        }
    }
}

输出结果如下：

Account holder name: Tom
Annual interest rate: 1.5
Balance: 1109.0
Mon May 10 09:44:35 CST 2021	D	30.0	1030.0	Deposit
Mon May 10 09:44:35 CST 2021	D	40.0	1070.0	Deposit
Mon May 10 09:44:35 CST 2021	D	50.0	1120.0	Deposit
Mon May 10 09:44:35 CST 2021	W	5.0	1115.0	Withdraw
Mon May 10 09:44:35 CST 2021	W	4.0	1111.0	Withdraw
Mon May 10 09:44:35 CST 2021	W	2.0	1109.0	Withdraw

可以看到，NewAccount类成功地记录了账户的交易记录，并且测试程序输出了账户持有者名字、利率、余额和所有的交易。