如何设置透支限额

Question

我试图做的是设置一个透支限额，即-150。如果用户余额为-150，则用户不能再提取。我的代码如下：

撤回方法

public void Withdraw(double amount){


    if (amount + 5 > balance ){ //If amount and transaction fee is greater than balance then apply for overdraft
        System.out.println("Insufficent funds");
        System.out.println("Would you like to apply for an ovedraft?");
        System.out.println("1:Yes");
        System.out.println("2:No, return me back to menus");
        Choice = Option.nextLine();
        if (Choice.equalsIgnoreCase("1")){
         if((balance = balance - amount+5)<=-150){   //If balance is grater than 150 , apply for overdraft
             System.out.println("You have exceeded your Overdraft Limit, you will now be returned back to the menus");
         return;

        }
        else{ //if not exceeding bank balance
            balance -= amount + 5; 
            System.out.println("You have withdrawen £" + amount);
            System.err.println("You now have a balance of £" +balance);
            return; 
        }
    }
}

}

它们都属于同一类，即“Account”，现在发生的情况是，消息确实出现了-（“您已经超过了透支限额，您现在将返回菜单”）并返回菜单，但当我去检查余额时，钱仍然被扣除，并显示超过-150的余额，例如-190。我如何才能确定-150是限额，并且不再扣除。希望问题被理解。

Answer 1

除了以上所有答案，我还将添加以下内容：

如果我有1美元，我透支了50美元，那么我的账户可以是

1美元-55美元=-54美元

但是有这个条件在这里是不可能的

if (amount + FEES > balance) { // If amount and transaction fee is greater than balance then apply for overdraft
System.out.println("Insufficent funds");

Answer 2

if（（余额=余额-金额5）

其次，你实际上是在改变你这里的平衡（=是赋值运算符）。你也写了

if（余额-（金额5）

Answer 3

问题是：

if ((balance = balance - amount + 5) <= -150) {

这里的关键是=。这是在支票前分配新金额。

像这样的事情可能会避免这个问题。

    if (balance - amount - 5 < 0) {
        System.out.println("Insufficent funds");
        System.out.println("Would you like to apply for an ovedraft?");
        System.out.println("1:Yes");
        System.out.println("2:No, return me back to menus");
        Choice = Option.nextLine();
        if (Choice.equalsIgnoreCase("1")) {
            if (balance - amount - 5 <= -150) {
                System.out.println("You have exceeded your Overdraft Limit, you will now be returned back to the menus");
            } else { //if not exceeding bank balance
                balance -= amount + 5;
                System.out.println("You have withdrawen £" + amount);
                System.err.println("You now have a balance of £" + balance);
            }

注意更明确的计算（if（余额-金额-5