java - 在Java中输入无效后重新提示用户(try和catch)

现在，它在发生一个错误后无限循环地循环。捕获后如何使它回到尝试状态？布尔条件已正确声明，没有编译错误或其他任何东西。该类中的其余代码有些混乱，因为我在等待有关重试的答案。

double base = 0;
double height = 0;
double area = 0;
boolean again = true;
while (again) {
    try {
        System.out.print("Enter the length of base of triangle in cm : ");
        base = input.nextDouble();
        again = false;
    } catch (Exception ex) {
        System.out.println("Invalid input");
        input.next();
    }

    try {
        System.out.print("Enter the length of height of triangle in cm : ");
        height = input.nextDouble();
    } catch (Exception ex) {
        System.out.println("Invalid Input");
        String next = input.next();
    }
    area = (base * height) / 2;

最佳答案

使用hasNextDouble（）而不是使用try / catch异常，因为您没有显式捕获InputMismatchException

   while (again) {

             // if the next is a double, print the value
             if (input.hasNextDouble()) {
                base = input.nextDouble();
                System.out.println("You entered base: " + base);
                again = false;
             } else {
                // if a double is not found, print "Not valid"
                System.out.println("Not valid :" + input.next());
                again = true;
             }


      }
    again = true;
    while (again) {

             // if the next is a double, print the value
             if (input.hasNextDouble()) {
                height = input.nextDouble();
                System.out.println("You entered height: " + height);
                again = false;
             } else {
                // if a double is not found, print "Not valid"
                System.out.println("Not valid :" + input.next());
                again = true;
             }


      }
      area = (base * height) / 2;