每次运行代码时都会重置余额变量

Question

我编写了一个 ATM 接口，用户可以在其中取款、存款或检查他/她的帐户余额。在此代码中，每次我再次运行代码时，余额都会重置为 15000（我的初始设置值）。

这是我的代码：

import java.util.Scanner;

abstract class ATMmachine {
    abstract void depositAmount();
    abstract void withdrawAmount();
}

class userAccount extends ATMmachine {

    Scanner sc = new Scanner(System.in);
    private int withdraw, deposit;
    private int balance = 15000;

    public void withdrawAmount() {
        boolean positiveAmount = true;
        while (positiveAmount) {
            System.out.print("Please enter withdrawal amount:");
            withdraw = sc.nextInt();
            if (withdraw < 0) {
                System.out.println("Please enter a positive number!");
            }
            else if (withdraw >= 0) {
                positiveAmount = false;
            }
        }

        if (withdraw <= balance) {
            balance -= withdraw;
            System.out.println("An amount of " + withdraw + " has been withdrawn. Remaining balance: " + balance);
            positiveAmount = false;
        }
        else if (withdraw > balance) {
            System.out.println("Error, insufficent funds!");
        }
    }

    public void depositAmount(){
        boolean positiveDeposit = true;
        while (positiveDeposit) {
            System.out.print("Please enter deposit amount:");
            deposit = sc.nextInt();
            if (deposit > 0) {
                balance += deposit;
                System.out.println("You made a deposit of " + deposit + " your balance now is : " + balance);
                positiveDeposit = false;
            }
            else {
                System.out.println("Error, balance cannot be negative!");
            }
        }
    }

    public int getBalance() {
        return balance;
    }
}


public class atmsystem {
    public static void main(String[] args) {
        String[] options = {"Withdraw amount","Deposit amount","Check your balance"};

        Scanner scanner = new Scanner(System.in);
        userAccount obj1 = new userAccount();
        try {
            System.out.print("Welcome to Platino bank, please select an option: \n");
            for (int index = 0; index < options.length; index++) {
                System.out.println(index + 1 + " => " + options[index]);
            }
            int select = scanner.nextInt();
            if (select == 1){
                obj1.withdrawAmount();
            }
            else if (select == 2) {
                obj1.depositAmount();
            }
            else if (select == 3) {
                obj1.getBalance();
                System.out.println(obj1.getBalance());
            }
            else {
                System.out.println("Error, no such option exists!");
            }
            scanner.close();
        }
        catch (Exception e) {
            System.out.println("Please enter an integer value!");
        }
    }
}

这段代码出了什么问题，我可以进行哪些更改，以便每次 getter 方法都能反映更新后的余额？

Answer 1

你只需要在你的代码中添加两行，并进行一些小的修改，错误是在第一次操作后，你退出应用程序，你必须创建一个循环，让你继续操作：

class atmsystem {

  public void main() {
     String[] options = { "Withdraw amount", "Deposit amount", "Check your balance", "Exit" };

     Scanner scanner = new Scanner( System.in );
     userAccount obj1 = new userAccount();
     try {
        System.out.print( "Welcome to Platino bank, please select an option: \n" );

          // insert this line, to create a loop
        while( true ) {
           for( int index = 0; index < options.length; index ++ ) {
              System.out.println( index + 1 + " => " + options[ index ] );
           }
           int select = scanner.nextInt();
           if( select == 1 ) {
              obj1.withdrawAmount();
           }...

             // with this "else if", we give the user the option to exit
           else if( select == 4 ) {
              System.out.println( "bye" );
              scanner.close();
              break;
           }
           else {
              System.out.println( "Error, no such option exists!" );
           }

             // move "scanner.close();" to "else if" with "select == 4"
        }
     }
     catch( Exception e ) {
        System.out.println( "Please enter an integer value!" );
     }
   }
}