java - 将变量传递给扩展类并调用方法

Question

我现在完全不知所措。我正在尝试开发一个程序来显示两个储蓄账户的 Months、Account # 和 Balance 并更新 Balance 因为帐户的利息是应计的:

• 第一个账户每月产生 10,002 利息，年利率为 1.2%。
• 对于第二个帐户，10,003 利息按季度计息，年利率为 4%。

为了做到这一点，我必须设计四个单独的类。 SavingsAccount、SavingsAccountDriver、FlexibleSavingsAccount 和 CDSavingsAccount。 SavingsAccount 是 FlexibleSavingsAccount 和 CDSavingsAccount 的父类。 SavingsAccountDriver 是主类。

在 SavingsAccount 中，我有一个在 SavingsAccountDriver 中调用的方法 setAnnualInterestRate()。此方法设置每个帐户的利率。我遇到的问题是将此值传递给扩展类 FlexibleSavingsAccount 和 CDSavingsAccount 以便我可以通过添加每个帐户的利率来更新余额。如果有人可以帮助我完成此操作，我将不胜感激。

SavingsAccountDriver:

public class SavingsAccountDriver {
    public static void main (String[] args) {
        SavingsAccount saver1 = new SavingsAccount(10002, 2000); //create new SavingsAccount object
        SavingsAccount saver2 = new SavingsAccount(10003, 3000); //create new SavingsAccount object

        saver1.setAnnualInterestRate(.012); //sets AnnualInterestRate for 'saver1' object
        saver2.setAnnualInterestRate(.04); //sets AnnualInterestRate for 'saver2' object

        System.out.println("\nMonthly balances:\n");
        System.out.println("Month " + " Account# " + " Balance " + "      " + " Month " + " Account# " + " Balance ");
        System.out.println("----- " + " -------- " + " ------- " + "      " + " ----- " + " -------- " + " ------- ");


        System.out.println(saver1.getAccountNumber() + " / " + saver1.getBalance() + " / " + saver1.getInterest());
        System.out.println(saver2.getAccountNumber() + " / " + saver2.getBalance() + " / " + saver2.getInterest());

        /*for(int month = 0; month <= 12; month++) {
            switch(month) { // switch that outputs month, account number, and balance for both accounts (Some non-needed cases used to make output look cleaner)
                case 0:
                    System.out.println(month + "      " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "         " + month + "      " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
                case 4: 
                    saver1.addInterest();
                    //saver2.addInterest();

                    System.out.println(month + "      " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "         " + month + "      " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
                case 10:
                    saver1.addInterest();
                    //saver2.addInterest();

                    System.out.println(month + "     " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "        " + month + "     " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
                case 11:
                    saver1.addInterest();
                    //saver2.addInterest();

                    System.out.println(month + "     " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "        " + month + "     " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
                case 12:
                    saver1.addInterest();
                    //saver2.addInterest();

                    double totalBalance = saver1.getBalance() + saver2.getBalance();
                    System.out.println(month + "     " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "        " + month + "     " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
                default:
                    saver1.addInterest();
                    //saver2.addInterest();

                    System.out.println(month + "      " + saver1.getAccountNumber() + "     " + saver1.getBalance() + "        " + month + "      " + saver2.getAccountNumber() + "     " + saver2.getBalance());
                    break;
            }
        }*/
    }
}

储蓄账户:

public class SavingsAccount {
    // variables specific to SavingsAccount class
    public double annualInterestRate;
    private final int ACCOUNT_NUMBER;
    public double balance;

    //constructor with account number and balance parameters
    public SavingsAccount(int account_number, double balance) {
        this.ACCOUNT_NUMBER = account_number;
        this.balance = balance;
    }

    //returns account number
    public int getAccountNumber() {
        return this.ACCOUNT_NUMBER;
    }

    //returns balance
    public double getBalance() {
        return this.balance;
    }

    //sets interest rate
    public void setAnnualInterestRate (double interestRate) {
        this.annualInterestRate = interestRate;
    }
}

灵活储蓄账户:

public class FlexibleSavingsAccount extends SavingsAccount{

        public FlexibleSavingsAccount(int account_number, double balance) {
            super(account_number, balance);
        }

        //returns interest
        public double getInterest() {
            return annualInterestRate;  
        }
}

Answer 1

您可能希望将 getInterest 添加为抽象方法并将 SavingsAccount 声明为抽象类。然后你将拥有编译器已知的方法来调用，你将被迫在子类中提供正确的实现