撤銷異常Java

Question

我向用戶詢問要從餘額中提取的金額時遇到問題。我有一個叫撤回的方法，我通過他們的平衡。然後，我想檢查他們想要提取的金額是否低於餘額。如果是，我想讓用戶重試。

到目前爲止，它檢查輸入，但我不斷得到每次嘗試的輸出。

public void withdraw (double balance){ 
System.out.println("How much would you like to withdraw?"); 
double amount = keyboard.nextDouble(); 

try 
{ 
    if(amount > balance) 
    { 
     throw new IncorrectWithdrawException(); 
    } 
} 

catch(IncorrectWithdrawException e) 
{ 
    System.out.println(e.getMessage()); 
    withdraw(balance);// keeps calling the method for a loop if they keep entering incorrect amount 
} 

balance = balance-amount; 
System.out.println("You have withdrawn "+amount+ " and your new balance is "+balance); }} 

輸出：

什麼是你的平衡？ 100 您要退出多少？200 ------錯誤------這不是一個有效的撤回金額。你想退出多少？ 500 ------錯誤------這不是一個有效的撤回金額。你想退出多少？ 50

您已經撤出50.0和新餘額爲50.0

我不希望下面的最後兩個輸出...

您已經撤出500.0和新餘額爲-400.0您已取消200.0，您的新餘額爲-100.0

Answer 1

public void withdraw (double balance) 
{ 
    System.out.println("How much would you like to withdraw?"); 
    double amount = keyboard.nextDouble(); 

    try 
    { 
    if(amount < balance) 
    { 
    balance = balance-amount; 
    System.out.println("You have withdrawn "+amount+ " and your new balance is "+balance); 
    } 
    else 
    throw new IncorrectWithdrawException(); 
    } 
catch(IncorrectWithdrawException e) 
{ 
    System.out.println(e.getMessage()); 
    withdraw(balance);// keeps calling the method for a loop if they keep entering incorrect amount 
} 
}