if语句Java银行程序如何从余额中扣除

Question

我有一个简单的银行程序，你可以检查你的余额，存款和取款。顺便说一下，这是一个循环，因此您可以进行多个事务

char anotherTransact, option;
    int balance;
    double deposit, withdraw;
    
    
    do {
    System.out.println("\nWelcome to ABC BANK \n");
    
    System.out.println("B - Check for Balance");
    System.out.println("D - Make Deposit");
    System.out.println("W - Make Withdraw");
    System.out.println("Q - Quit");
    
    
        System.out.print("\nSelect an option : ");
        option = scan.next().charAt(0);
        
        
        balance = 100000; 
        if ((option == 'B') || (option == 'b')) {
            System.out.println("\nYour current balance is " +balance);
        }
        
        else if ((option == 'D') || (option == 'd')) {
            System.out.print("\nEnter amount to Deposit : ");
            deposit = scan.nextDouble();
            if (deposit > 1) {
                System.out.println("Deposit Transaction is successfully completed.");
                double newBalance = 100000 + deposit; 
            }
            else if (deposit > 500000) {
                System.out.println("Deposit Amount must not be greater than 500,000");
            }
            else {
                System.out.println("Deposit must be greater than zero");
            }
        }
        
        else if ((option == 'W') || (option == 'w')) {
            System.out.print("\nEnter amount to Withdraw : ");
            withdraw = scan.nextDouble();
            if (withdraw % 100 == 0) {
                System.out.println("Withdrawal Transaction is successfully completed.");
                
            }
            else if (withdraw > 150000) {
                System.out.println("Withdrawal Amount must not be greater then 150,000");
            }
            else {
                System.out.println("Withdrawal Amount must be greater than zero");
            }
        }
        
        else {
            System.out.println("\nInvalid entry, enter any valid option : (B/D/W/Q)");
        }
        
        System.out.print("\nWant to Transact another (Y/N?) ");
        anotherTransact = scan.next().charAt(0);        
    }
    
    while ((anotherTransact == 'Y') || (anotherTransact =='y'));

问题是，当我选择取款选项时，我不知道它应该如何在下一次银行交易中扣除余额，并在余额中添加存款

比如说，我会在银行存40美元。然后做一笔新的交易，打开我的余额，将我存入的40美元加起来。我怎样才能把存款加到我的余额中呢？我取款时如何扣除

Answer 1

首先，从余额中扣除只是balance -= withdrawal，这与balance = balance - withdraw相同，这将更新变量balance。当您想要打印currentnt余额时，只需调用此变量
double newBalance = 100000 + deposit;不会更新您的余额，因为您只打印余额而不是新余额
其次，balance不应该是一个int变量
您的一些交易规则不正确。支取时，应检查余额是否大于支取金额，支取金额是否大于0（balance > withdraw && withdraw > 0）。另外，withdraw % 100 == 0对我来说没有意义，它不是"Withdrawal Amount must be greater than zero"的条件

Answer 2

在会计中，您不跟踪任何余额值，因为它总是动态计算的
在资产负债表（通常是数据库表）中，存款是正值（>；0），取款是负值（<；0）。如果使用类似于int或double的数据类型。。。你只能代表美分；通常BigDecimal被用来表示货币价值

如果您想让这个程序以某种方式工作，请将所有事务推送到ArrayList中。我的意思是，一个愚蠢的问题是：你打算如何在不跟踪所有交易的情况下发布银行对账单

Answer 3

您需要更新balance变量。您在循环的每次迭代中将balance设置为100000。另外，我把它改为扫描。因为余额是一个整数。如果您想处理小数，请将balance更改为double，并将nextInt返回nextDouble

import java.util.Scanner;

class Main {  
  public static void main(String args[]) { 
    char anotherTransact, option;
    int balance = 100000;
    double deposit, withdraw;
    Scanner scan = new Scanner(System.in);
    
    do {
    System.out.println("\nWelcome to ABC BANK \n");
    
    System.out.println("B - Check for Balance");
    System.out.println("D - Make Deposit");
    System.out.println("W - Make Withdraw");
    System.out.println("Q - Quit");
    
    
        System.out.print("\nSelect an option : ");
        option = scan.next().charAt(0);
        
        
        if ((option == 'B') || (option == 'b')) {
            System.out.println("\nYour current balance is " +balance);
        }
        
        else if ((option == 'D') || (option == 'd')) {
            System.out.print("\nEnter amount to Deposit : ");
            deposit = scan.nextInt();
            if (deposit > 1) {
                System.out.println("Deposit Transaction is successfully completed.");
                balance += deposit; 
            }
            else if (deposit > 500000) {
                System.out.println("Deposit Amount must not be greater than 500,000");
            }
            else {
                System.out.println("Deposit must be greater than zero");
            }
        }
        
        else if ((option == 'W') || (option == 'w')) {
            System.out.print("\nEnter amount to Withdraw : ");
            withdraw = scan.nextInt();
            if (withdraw % 100 == 0) {
                balance -= withdraw;
                System.out.println("Withdrawal Transaction is successfully completed.");
                
            }
            else if (withdraw > 150000) {
                System.out.println("Withdrawal Amount must not be greater then 150,000");
            }
            else {
                System.out.println("Withdrawal Amount must be greater than zero");
            }
        }
        
        else {
            System.out.println("\nInvalid entry, enter any valid option : (B/D/W/Q)");
        }
        
        System.out.print("\nWant to Transact another (Y/N?) ");
        anotherTransact = scan.next().charAt(0);        
    }
    
    while ((anotherTransact == 'Y') || (anotherTransact =='y')); 
  } 
}