Question

我创建了一个主要的Java程序，它像银行一样，为用户提供余额，提款和转账。

import java.util.Scanner;

public class Lab12 {
    public static void main(String[] args)
    {
        //Creating Two BankAccounts
        BankAccount B1 = new BankAccount(1000, "ASU_ACCOUNT_110");
        BankAccount B2 = new BankAccount(500, "ASU_ACCOUNT_100");
        double amount;
        Scanner scan  = new Scanner(System.in);

        //Account Deposit
        System.out.println("Please Enter amount to deposit into ASU_ACCOUNT_110 Account");
        amount = scan.nextDouble();
        if(!B1.deposit(amount))
            System.out.println("Error depositing amount in account. Please enter positive value.");
        else
            System.out.println("Successfully deposited $"+amount+". The current balance is "+B1.getBalance() );

        //Account Withdrawal
        System.out.println("Please Enter the amount you would like to withdraw from ASU_ACCOUNT_110");
        amount = scan.nextDouble();
        if(!B1.withdraw(amount))
            System.out.println("Error withdrawing amount. You are either overdrawing or you have entered a negative value");
        else
            System.out.println("Successfully withdrew $"+amount+". The current balance is "+B1.getBalance());

        //Account Transfer
        System.out.println("Please Enter the amount you would like to transfer from ASU_ACCOUNT_110 to ASU_ACCOUNT_100");
        amount = scan.nextDouble();
        if(!B1.transfer(amount, B2))
        {
            System.out.println("Error transfering amount. You are either overdrawing or you have entered a negative value");
        }
        else
        {
            System.out.println("Successfully transferred $"+amount+".\nThe current balance in ASU_ACCOUNT_110 is "+B1.getBalance());
            System.out.println("The current balance in ASU_ACCOUNT_100 is "+B2.getBalance());
        }

        //Account Display
        System.out.println("\nThe details of the two accounts are:");
        System.out.println("------------------------------------------");
        display(B1);
        System.out.println("------------------------------------------");
        display(B2);
    }

    public static void display(BankAccount B)
    {
        System.out.println("The Account Number is "+B.getAccountNumber());
        System.out.println("The balance is "+B.getBalance());
    }
}

我创建了第二个包含方法并获取并调用余额的类

public class BankAccount {

    private String AccountNumber;
    private double balance;

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

    public boolean deposit(double amount) 
    {
        return true;
    }

    public double getBalance() 
    {
        return balance;
    }

    public boolean withdraw(double amount) 
    {
        return true;
    }

    public boolean transfer(double amount, BankAccount b2) 
    {
        return true;
    }

    public String getAccountNumber() 
    {
        return AccountNumber;
    }
}

问题是，当我输入存款，提款，转账的负数时，我没有收到我在主类中输入的错误

有什么想法吗？

Answer 1

您不会在BankAccount.deposit（double）中的任何位置检查该数字是否为负数。您需要检查代码是否为负数：

public boolean deposit(double amount) 
{
    if(amount<0)
    {
        return false;
    }else{
        return true;
    }
}

Answer 2

您在BankAccount中的方法始终返回true。除非你提供这样做的实现，否则你不能指望它们有时会发出故障信号。

例如：

public boolean withdraw(double amount) 
{
    return true;
}

永远不会发出失败信号，因为始终返回true。为了使您的方法按照您希望的方式运行，您必须添加更复杂的行为。类似的东西：

public boolean withdraw(double amount) 
{  
    //if the withdrawal is positive and does not exceed the balance
    if (amount >= 0 && amount <= balance)
    {
         //remove money and signal success
         balance -= amount;
         return true;
    }
    //if either condition failed, signal failure
    return false;
}

看起来你只是忘了实现这些方法。或者你对编程有一个基本的误解。

Answer 3

存款，取款和转账方式总是正确的。因此，您永远不会看到错误消息。

我不能让java文件给我错误

3 个答案: