java - 我的 Java 程序中的余额未更新

Question

我编写了一个java程序，其中子类是BankAccount，SavingsAccount是它的子类，我正在用它进行一些交易，但余额没有得到更新并仅显示 0.00 作为输出。

这是我的代码:

public class BankAccountTest {

    public static void main(String[] args) {
        SavingsAccount savingsAccount = new SavingsAccount(879101,0,0.04);
        savingsAccount.deposit(500);
        savingsAccount.withdraw(500);
        savingsAccount.deposit(1500);
        savingsAccount.deposit(500);
        savingsAccount.withdraw(500);
        savingsAccount.deposit(5000);
        savingsAccount.deposit(500);
        savingsAccount.annualCredit();
        System.out.println(savingsAccount);

    }
}

class BankAccount {

        private int accountNumber;
        protected double balance;



    public BankAccount( int accountNumber, double balance)
        {
            this.accountNumber = accountNumber;
            this.balance = balance;
        }

        public int getAccountNumber () {
            return accountNumber;
        }

        public double getBalance () {
            return balance;
        }

        public void setAccountNumber ( int accountNumber){
            this.accountNumber = accountNumber;
        }

        public void setBalance ( double balance){
            this.balance = balance;
        }

        public void deposit ( double amount){
            balance = balance + amount;
        }

        public void withdraw ( double amount){
            if (amount <= balance)
                balance = balance - amount;
        }


        public String toString () {
            return String.format("Account Number=%d%nBalance=%.2f%n", accountNumber, balance);
        }

    }

class SavingsAccount extends BankAccount{

    private double interestRate;

    public SavingsAccount(int accountNumber, double balance, double interestRate) {
        super(accountNumber, balance);
    }
    public void deposit(double amount){
        balance = balance+(interestRate*amount);

    }
    public void withdraw(double amount) {
        super.withdraw(amount);
    }


    public void annualCredit(){
        if (balance<=1000){
            balance=interestRate*balance;
        }
        else if(balance<=5000){
            balance=2*interestRate*balance;
        }
        else if(balance>5000){
            balance=3*interestRate*balance;
        }
    }
    public double getInterestRate(){
        return interestRate;
    }



    public String toString(){
        System.out.println("Account= "+getAccountNumber()+"\nBalance= "+balance+"\nInterestRate= "+interestRate);
        return null;
    }

}

输出:

Account= 879101
Balance= 0.0
InterestRate= 0.0
null

Answer 1

您从未在 SavingsAccount 构造函数中设置 interestRate。由于存款乘以该值(并且为零)，因此它永远不会更新。

public SavingsAccount(int accountNumber, double balance, double interestRate) {
    super(accountNumber, balance);
    this.interestRate = interestRate;
}

此外，存款可能不应该支付利息。

public void deposit(double amount) {
    balance += amount;
}