(新的 Account 类）编程练习题 9.7 中给出了一个

import java.util.ArrayList; import java.util.Date; public class E1102_2019110009 { public static void main(String[] args) {
Account account=new Account("George",1122,1000,0.015);
System.out.println("账户持有者："+account.name+"\n账户利率："+account.annualInterestRate);
account.withDraw(30);
account.withDraw(40);
account.withDraw(50);
account.deposit(5);
account.deposit(4);
account.deposit(2);
System.out.print("交易流水："+account.transactions);
    }
} class Account{ public String name; int id=0; double balance=0; double annualInterestRate=0;
    Date dataCreated;
    ArrayList transactions=new ArrayList(); public Account() {
    } public Account(int id, double balance) { this.id = id; this.balance = balance;
    } public Account(String name, int id, double balance) { this.name = name; this.id = id; this.balance = balance;
    } public Account(String name, int id, double balance, double annualInterestRate) { this.name = name; this.id = id; this.balance = balance; this.annualInterestRate = annualInterestRate;
    } public void setId(int id) { this.id = id;
    } public void setBalance(double balance) { this.balance = balance;
    } public void setAnnualInterestRate(double annualInterestRate) { this.annualInterestRate = annualInterestRate;
    } public Date getDataCreated() { return dataCreated;
    } public int getId() { return id;
    } public double getBalance() { return balance;
    } public double getAnnualInterestRate() { return annualInterestRate;
    } public void withDraw(double amount){ balance-=amount; transactions.add(new Transaction('W&(455)#39;,amount,getBalance()));
    } public void deposit(double amount){ balance+=amount; transactions.add(new Transaction('D&(656)#39;,amount,getBalance()));
    }
} class Transaction { char type; double amount; double balance;
    String description; public void setType(char type) { this.type = type;
    } public void setAmount(double amount) { this.amount = amount;
    } public void setBalance(double balance) { this.balance = balance;
    } public void setDescription(String description) { this.description = description;
    } public char getType() { return type;
    } public double getAmount() { return amount;
    } public double getBalance() { return balance;
    } public String getDescription() { return description;
    } public Transaction(char type, double amount, double balance, String description) { this.type = type; this.amount = amount; this.balance = balance; this.description = description;
    } public Transaction(char type, double amount, double balance) { this.type = type; this.amount = amount; this.balance = balance;
    } @Override  public String toString() { return "type=" + type + ", amount=" + amount + ", balance=" + balance ;
    }
}