Question

我应该使用抽象方法BankAcct设计一个computeIntt()类。 Save和Time是BankAcct的种类。问题是我无法实现兴趣和新余额的显示

这是我目前的代码：

public abstract class BankAcct 
{
    private int accountNumber;
    private String accountName;
    private double bal;

    public BankAcct(int act, String name, double m)
    {
        accountNumber = act;
        accountName = name;
        bal = m;
    }

    public double getBalance()
    {
        return bal;
    }

    public String getAccountName()
    {
        return accountName;
    }

    public int getAccountNumber()
    {
        return accountNumber;
    }

    public void deposit(double m)
    {
            bal+=m;
    }

    public void withdraw(double m)
    {
        bal-=m;
    }

    public abstract double computeInt();
}

public class Save extends BankAcct 
{
    public Save(int act, String name, double m)
    {
        super(act, name, m);
    }

    int act;
    String name="";
    double m;

    public double computeInt()
    {
        return m * 0.0025;
    }

}

public class Time extends BankAcct 
{
    public Time(int act, String name, double m)
    {
        super(act, name, m);
    }

    int act;
    String name="";
    double m;

    public double computeInt()
    {
        return m * 0.033;
    }

}

public class MainPr 
{
    public static void main(String[] args)
    {
        BankAcct sav = new Savings(1234, "ABC", 10000);
        BankAcct td = new TimeDeposit(9876, "DEF", 20000);

        // display the current balance

        System.out.println(sav.getAccountName() + " with account number " +
                    sav.getAccountNumber() + " has a balance of " +
                    sav.getBalance());

        System.out.println(td.getAccountName() + " with account number " +
            td.getAccountNumber() + " has a balance of " +
            td.getBalance());

        // deposit money

        sav.withdraw(5000.0);

        // display current value with its interest

        System.out.println("\n" + sav.getAccountName() + " with account number " +
            sav.getAccountNumber() + " earned an interest of " +
            sav.computeInt());

        System.out.println(sav.getAccountName() + " with account number " +
            sav.getAccountNumber() + " has a NEW BALANCE of " +
            sav.getBalance());

        td.deposit(2000.0);

        System.out.println("\n" + td.getAccountName() + " with account number " +
            td.getAccountNumber() + " earned an interest of " +
            td.computeInt());

        System.out.println(td.getAccountName() + " with account number " +
            td.getAccountNumber() + " has a NEW BALANCE of " +
            td.getBalance());
    }
}

MainPr将为以下数据实例化两个对象：保存帐号为1234; ABC的帐户名称;余额10,000。时间账号为9876;帐户名称DEF;余额20,000。

这应该是输出：CORRECT ONE

帐号为1234的ABC余额为10000.0

帐号为9876的DEF余额为20000.0

账号为1234的ABC赚取利息25.0

账号为1234的ABC新余额为5025.0

帐号为9876的DEF赚取利息660.0

帐号为9876的DEF的余额为22660.0

但我的程序产生错误的输出：

帐号为1234的ABC余额为10000.0

帐号为9876的DEF余额为20000.0

账号为1234的ABC赚取利息0.0

账号为1234的ABC新余额为5000.0

帐号为9876的DEF赚取利息0.0

帐号为9876的DEF的余额为22000.0

在这种情况下，保存利率为0.25％，而利息时间为3.3％。余额取决于存款或取款。

请帮助我。感谢

Answer 1

您的实例变量m在您的子类中始终为0（从未初始化），但它们看起来设置为bal类中的BankAcct。这不适合computerInterest中的TimeDeposit方法：

public double computeInterest() {
    return getBalance() * 0.033;
}

应在其他子类中提供类似的修补程序，或者至少初始化m个变量。在相关的说明中，您的子类不需要定义act或name，因为您的超类BankAcct已经定义并存储了它。

此外，您的computerInterest并未修改您的计划似乎期望的余额。如果是这种情况，这可能更合适：

public double computeInterest() {
    double interest = getBalance() * 0.033;
    deposit(interest);
    return interest;
}

抽象类/方法实现

1 个答案: