继承javabank帐户（java）

Question

我在一个遗产银行账户上工作，该账户有5个等级。在其中一个类别（InterestFreeDeposit）中，应使用至少10美元创建帐户。我应该如何编写这部分的代码？ 以下是我迄今为止所做的工作：

超类：

import java.util.Scanner;
import java.io.FileReader;
public class Account {
    private String owner;
    private double balance;
    private int accountNumber;
    private double interestRate;
        public Account( String owner,double balance, int accountNumber , double interestRate){
            this.balance=balance;
            this.owner=owner;
            this.accountNumber=accountNumber;
            this.interestRate=interestRate;
        }
        public void deposit(double amount) {
                if(amount>0) {
                    this.balance+=amount;
                }

        }
        public void withdraw(double amount) {
                if(amount>0 && balance>=amount) {
                    this.balance-=amount;
                }
        }
        public double getBalance() {
            return balance;
        }
        public void setBalance(double amount) {
            this.balance = amount;
        }

        public String getOwner() {
            return owner;
        }


public void setOwner(String owner) {
            this.owner = owner;
        }
        public int getAccountNumber() {
            return accountNumber;
        }
        public void setAccountNumber(int accountNumber) {
            this.accountNumber = accountNumber;
        }
        public double getInterestRate() {
            return interestRate;
        }
        public double setInterestRate(double interestRate) {
            //System.out.println("Enter the period(month):");

            return this.balance +=balance * interestRate/100;
        }

子类（InterestFrreClass）：

public class InterestFreeDeposit extends Account {
public InterestFreeDeposit(String owner, double balance, int accountNumber, double interestRate) {
    super(owner, balance, accountNumber, interestRate);
    // TODO Auto-generated constructor stub
}
public void interest() {
    super.setInterestRate(0.0) ;


    }

}

Answer 1

设置值时需要添加检查，在本例中，检查发生在InterestFreeDeposit的构造函数中。问题是当值低于10时，您希望如何反应。您可以抛出一个IllegalArgumentException：

public InterestFreeDeposit(String owner, double balance, int accountNumber, double interestRate) {
    super(owner, balance, accountNumber, interestRate);
    if(balance < 10){
        throw new IllegalArgumentException("balance must be at least 10");
    }
}

这种方法的问题是IllegalArgumentException是一个未检查的异常，这意味着如果抛出构造函数，则构造函数的调用方不会被迫处理它

Answer 2

您可以在子类构造函数中使用三元运算符来默认为10.0最小值：

public class InterestFreeDeposit extends Account {
     public InterestFreeDeposit(String owner, double balance, int accountNumber, double interestRate) {
         super(owner, balance < 10.0 ? 10.0 : balance, accountNumber, interestRate);
     }
}

三元运算符可视为内联if。因此，您有以下结构：

condition ? condition is true : condition is false

在上面的代码片段中，它只是检查所提供的余额是否低于10.0。如果是，则将其设置为10，否则将传递：

balance < 10.0 ? 10.0 : balance