如何實現循環以使程序再次要求用戶輸入而不是結束程序

Question

ans = JOptionPane.showInputDialog(null, "Enter amount to be withdrawn from checking");
double withCheck = Double.parseDouble (ans);
if (withCheck >= checking)
    {
    JOptionPane.showMessageDialog(null, "You do not have enough in your account for that.");
    }
else
    {
    double sum = checking - withCheck;
    JOptionPane.showMessageDialog(null, "Your checking balance is now: $" + sum + ", and your savings balance is: $" + savings);
    }
}

當前，這段代碼在withCheck> = check時結束程序，我想知道一種使用某種循環再次詢問該問題的方法，直到“ if”語句為假並可以繼續else語句為止。

Answer 1

只需添加一個帶有真實條件的while循環 ，並在某個條件變為真實時break它。

While(true)
{
    ans = JOptionPane.showInputDialog(null, "Enter amount to be withdrawn from checking");
    double withCheck = Double.parseDouble (ans);
    if (withCheck >= checking)
        {
        JOptionPane.showMessageDialog(null, "You do not have enough in your account for that.");
        }
    else
        {
        double sum = checking - withCheck;
        JOptionPane.showMessageDialog(null, "Your checking balance is now: $" + sum + ", and your savings balance is: $" + savings);
        break;
        }
    }
}