Java try-catch 在 do-while 循环内

Question

在下面显示的 Java 代码中，我接受两个双精度的用户输入，并将这些值包装在处理 InputMismatchException 的 try-catch 中。 我还在这个 try-catch 块周围包裹了一个 do-while 循环。 我正在尝试以处理以下情况的方式编写代码：如果用户为“number2”输入错误类型，则循环不会重新开始并要求用户重新输入“number1”。 我一直在摸索实现这一点的最佳方法，并对任何反馈或建议持开放态度。

所以测试用例是； 用户为 number1 输入了正确的类型，但为 number2 输入了错误的类型，在这种情况下，我该如何实现代码以便它只要求重新输入 number2 而不是重新启动整个循环。 我试过嵌套 try-catch、嵌套 do-whiles 等。有什么想法吗？

import java.util.InputMismatchException;
import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    boolean continueInput = true;

    do {
      try {
      System.out.print("Enter your first number: ");
      double number1 = input.nextDouble();

      System.out.print("Enter your second number: ");
      double number2 = input.nextDouble();

      System.out.println("You've entered the numbers " + number1 + " " + number2);

      continueInput = false;
    }
      catch (InputMismatchException ex) {
        System.out.println("Try again, a double is required.");
        input.nextLine();
      }
    } while (continueInput);
  }
}

Answer 1

您可以提取采用供应商的方法

private <T> T executeWithRetry(String initialText, String retryText, Supplier<T> supplier) {
    System.out.println(initialText);
    while (true) {
        try {
            return supplier.get();
        } catch (InputMismatchException ex) {
            System.out.println(retryText);
      }
    };
}

并像使用它一样

double number1 = executeWithRetry(
    "Enter your first number: ",
    "Try again, a double is required.",
    () -> input.nextDouble()
)

Answer 2

只需将读取 2 个值的过程分开即可。 这样，您可以单独检查是否发生 InputMismatchException 并为每个变量单独处理。

continueInput = false;
do {
    try {
        System.out.print("Enter your first number: ");
        double number1 = input.nextDouble();
    } catch (InputMismatchException ex) {
        System.out.println("Try again, a double is required.");
        continueInput = true;
    }
} while (continueInput);

continueInput = false;
do {
    try {
        System.out.print("Enter your second number: ");
        double number2 = input.nextDouble();
    } catch (InputMismatchException ex) {
        System.out.println("Try again, a double is required.");
        continueInput = true;
    }
} while (continueInput);

Answer 3

尝试这个，

        Scanner input = new Scanner(System.in);

        boolean continueInput = true;
        double number1 = 0;
        while (continueInput) {
            try {
                System.out.print("Enter your first number: ");
                number1 = input.nextDouble();
                continueInput = false;
            } catch (InputMismatchException ex) {
                System.out.println("Try again, a double is required.");
                input.nextLine();
            }
        }

        continueInput = true;
        double number2 = 0;
        while (continueInput) {
            try {
                System.out.print("Enter your second number: ");
                number2 = input.nextDouble();
                continueInput = false;
            } catch (InputMismatchException ex) {
                System.out.println("Try again, a double is required.");
                input.nextLine();
            }
        }
        System.out.println("You've entered the numbers " + number1 + " " + number2);