如何在捕捉到异常java后再次启动计算

Question

我是java新手，我正在尝试计算净收入，如果我得到负净值，我希望用户返回计算。我尝试使用try cat语句，但它无法返回到开始的位置。请帮助。

下面是我的代码

public class Main {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter your income: ");
        double income = scanner.nextDouble();

        System.out.print("Enter your expenses: ");
        double expenses = scanner.nextDouble();
        double nett = income - expenses;

        if (nett < 0) {

            try {
                System.out.println("Please enter correct expense value");

            } catch (Exception e) {

            }

        }

        System.out.println("Your nett income is " + nett);
    }
}

Answer 1

使用do while代替以下异常：

do { 
            System.out.print("Enter your expenses: ");
            expenses = scanner.nextDouble();
            nett = income - expenses;
        } while (nett<0);

Answer 2

嗯，try-catch块不是这样工作的，相反，您希望将程序包装在一个while循环中：

    public class Main {
        public static void main(String[] args) {
            
            double nett = -1;

            try (Scanner scanner = new Scanner(System.in)) {
    
                while (nett < 0) {

                    System.out.print("Enter your income: ");
                    double income = scanner.nextDouble();

                    System.out.print("Enter your expenses: ");
                    double expenses = scanner.nextDouble();
                    nett = income - expenses;

                    if (nett < 0) {
                        System.out.println("Please enter correct expense value");

                    }
                }
    
            } catch (Exception e) {
                System.out.println(e.toString);
            }
    
            System.out.println("Your nett income is " + nett);
        }
    }

我还将您的扫描仪封装在一个try resources块中，这样无论发生什么情况，它都会自动关闭。