Question

我试图获取利息和总余额，但是我不明白我的代码有什么问题

public class Account {

    private double bal;  //The current balance
    private int accnum;  //The account number

    public String owner;
    public int balance;

    public Account() {

    }

    public Account(int a)
    {    
        bal=0.0;
        accnum=a;

    }

    public void deposit(double sum)
    {
    if (sum>0) 
        bal+=sum;             
    else
        System.err.println("Account.deposit(...): "
                   +"cannot deposit negative amount.");    
    }

    public void withdraw(double sum)
    {
    if (sum>0)
        bal-=sum;    
    else
        System.err.println("Account.withdraw(...): "
                   +"cannot withdraw negative amount.");    
    }

    public double getBalance()
    {
        return bal;
    }

    public double getAccountNumber()
    {
        return accnum;
    }

    public String toString()
    {
        return "Acc: " + accnum + ": " + "Balance: " + bal;    
    }

    public final void print()
    {
    //Don't override this,
    //override the toString method
    System.out.println( toString() );    
    }   
}

SavingsAccount类

public class SavingsAccount extends Account{

    private  double monthlyInterestRate;

    public SavingsAccount( int a, double mI) 
    {
        super(a);
        monthlyInterestRate = mI;
    }

    public double getInterest() 
    {
        return  monthlyInterestRate*super.getBalance();
    }


    public double totalBalance(){
        return super.getBalance() + getInterest();
    }

    public String toString() 
    {
        return "Interest: " + getInterest()  + "\n" + 
                "Total balance: " + totalBalance();
    }


}

CurrentAccount类

public class CurrentAccount extends Account {

    private double overdraftLimit;

    public CurrentAccount() {}

    public CurrentAccount(int a, double overdraftLimit) 
    {

        super(a);
        setOverdraftLimit(overdraftLimit);
    }

    public void setOverdraftLimit(double overdrafLimit) 
    {
         this.overdraftLimit = overdrafLimit ;
    }

    public double getOverdraftLimit() 
    {
        return overdraftLimit;
    }

    public String toString()

        {
            return  "Overdraft limit: " + overdraftLimit;
        }



}

AccountMain类

public class AccountMain {

    public static void main(String[] args) {


        Account ac = new Account(100555);
        ac.deposit(2000);
        SavingsAccount sa = new SavingsAccount(100555, 0.2);
        CurrentAccount ca = new CurrentAccount(100555, 800);

        System.out.println(ac.toString());
        System.out.println(sa.toString());
        System.out.println(ca.toString());

输出为

Acc：100555：余额：2000.0

兴趣：0.0

总余额：0.0

透支额度：800.0

Answer 1

在您的代码中

public SavingsAccount（int a，double mI）{ 超级（a）; MonthlyInterestRate = mI; }

您正在呼叫

super（a）;

您拥有的超级帐户中的

公共帐户（int a）{
bal = 0.0; accnum = a; }

因此您的余额为0，因此public double getInterest（）返回0，因为
monthlyInterestRate * super.getBalance（）;
等于 monthlyInterestRate * 0

有2个子类别的银行帐户类别未显示结果

1 个答案: