Question

我不知道为什么try catch语句不起作用：

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

public class Main {
    protected static int intNum;
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        while(true) {
            System.out.println("[Shopping List] This is the shopping list GUI by Endercy.");
            System.out.println("[Shopping List] Controls are here:");
            System.out.println("[Shopping List] Type 1 to create a Shopping List");
            System.out.println("[Shopping List] Type 2 to enter a Shopping List name to view its contents");
            System.out.println("[Shopping List] Type 3 Add an item to your shopping list");
            System.out.println("[Shopping List] Type 4 to remove an item from your shopping list");
            System.out.println("[Shopping List] Type 5 to add a price to one of your items in your shopping list");
            intNum = scanner.nextInt();
            switch(intNum) {
                case 1:
                    System.out.println("test");
                    break;
                case 2:
                    System.out.println("test test");
                    break;
                case 3:
                    System.out.println("test test test");
                    break;
                case 4:
                    System.out.println("test test test test");
                    break;
                case 5:
                    System.out.println("test test test test test");
                    break;
                default:
                    while(true) {
                        System.out.println("I'm sorry, but this number is not on our controls list. Try again!");
                            try {
                                intNum = scanner.nextInt();
                            } catch (InputMismatchException e) {
                                System.out.println("Invalid Number, try again!");
                                intNum = scanner.nextInt();
                            }
                        switch(intNum) {
                            case 1:
                                System.out.println("test");
                                break;
                            case 2:
                                System.out.println("test test");
                                break;
                            case 3:
                                System.out.println("test test test");
                                break;
                            case 4:
                                System.out.println("test test test test");
                                break;
                            case 5:
                                System.out.println("test test test test test");
                                break;
                        }
                    }
            }
            break;
        }
        System.out.println("Thanks for trying out this thingy");
    }
}

这是代码，如果有人输入诸如283479234729472472983472984723或字符串等无效内容，我只想执行InputMismatchException。

但是当我运行它时，我输入类似的内容，它不允许我使用扫描仪再试一次，只是跳到：

Exception in thread "main" java.util.InputMismatchException: For input string: "879857294729847917412942472394724237492734923"
    at java.base/java.util.Scanner.nextInt(Scanner.java:2264)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
    at com.endercy.challenges.java.arraylist.shoppinglist.Main.main(Main.java:19)

它并不能让我输入另一个。

Answer 1

您应该将另一个try catch blok放入第一个scan.nextInt方法。我认为代码不会在那里传递并在其中引发异常

尝试捕获语句不会让我重试

1 个答案: