如何在不退出程序的情况下在do-while循环中添加if语句？

Question

我有两节课。这个程序几乎模拟了一个自动取款机。用户将要求存入、提取或查看用户银行帐户的余额。

首先，余额将被设置为零，然后用户可以存钱或取款。

如果用户选择存款，则帐户余额将添加到用户希望存入他/她帐户的金额。CheckingAccount类中的GetBalance方法返回用户帐户的余额，而ProcessDeployce将用户希望存入的金额添加到余额中，而ProcessCheck将用户选择的金额减少到余额中。

如果用户选择查看余额，那么它将打印用户余额。

public class CheckingAccount{
    double myBalance = 0;

    public double getBalance(){
        return myBalance;
    }

    public void processDeposit(double amount){
        myBalance += amount;
    }

    public void processCheck(double amount){
        myBalance -= amount;
    }
}

import java.util.Scanner;
public class TestCheckingAccount {

public static void main(String[] args) {

    CheckingAccount check = new CheckingAccount();

    Scanner in = new Scanner(System.in);

    String choice;
    double moneyAdded;
    double moneySubtracted;

    do
    {
        System.out.println("Deposit");
        System.out.println("Withdraw");
        System.out.println("Balance");
        System.out.println("Exit");
        System.out.println("**********************************************");
        System.out.println("Which operation would you like to use?");
        choice = in.nextLine();

        if(choice.equalsIgnoreCase("Deposit"))
        {
            System.out.println("How much money would you like to deposit?");
            moneyAdded = in.nextDouble();
            check.processDeposit(moneyAdded);
        }

        if(choice.equalsIgnoreCase("Withdraw"))
        {
            System.out.println("How much money would you like to withdraw?");
            moneySubtracted = in.nextDouble();

            check.processCheck(moneySubtracted);
        }
        else if(choice.equalsIgnoreCase("Balance"))
        {
            System.out.printf("$%.2f%n" , check.myBalance);
        }
        else if(choice.equalsIgnoreCase("Exit"))
        {
            System.exit(0);
        }

    }
    while(choice.equalsIgnoreCase("Deposit")||choice.equalsIgnoreCase("Withdraw")||choice.equalsIgnoreCase("Balance"));

    in.close();

}

}

我如何使程序，使它可以提取或存钱，但仍然循环，并回到菜单，它问用户是否他/她想存钱或取款，而不只是结束循环？

Answer 1

对于“exit”条件，可以使用无限循环和break。此外，还可以使用try-with-resourcesclose语句关闭扫描程序。就像，

try (Scanner in = new Scanner(System.in)) {      
  String choice;
  double moneyAdded;
  double moneySubtracted;

  while (true) {
    System.out.println("Deposit");
    System.out.println("Withdraw");
    System.out.println("Balance");
    System.out.println("Exit");
    System.out.println("**********************************************");
    System.out.println("Which operation would you like to use?");
    choice = in.nextLine();

    if (choice.equalsIgnoreCase("Deposit")) {
      System.out.println("How much money would you like to deposit?");
      moneyAdded = in.nextDouble();
      check.processDeposit(moneyAdded);
    } else if (choice.equalsIgnoreCase("Withdraw")) {
      System.out.println("How much money would you like to withdraw?");
      moneySubtracted = in.nextDouble();
      check.processCheck(moneySubtracted);
    } else if (choice.equalsIgnoreCase("Balance")) {
      System.out.printf("$%.2f%n", check.myBalance);
    } else if (choice.equalsIgnoreCase("Exit")) {
      break;
    }
  }
}