这个扫描仪怎么了？

Question

所以我有一些带有扫描仪的Java代码。当我犯错误时，我做错了什么？

// Creates a "scanner" for the input
Scanner readInput = new Scanner(System.in);

// Print out random integer and open close message.
System.out.println("Printing Random Numbers between 1-200: ");
int guess = readInput.nextInt();

错误(我对Java相当陌生，我编写的代码和4-5年前差不多。但忘记了)：

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at main.files.mian.main(mian.java:30)

Answer 1

如果输入数字(整数)以外的任何内容，则程序会崩溃。下面的代码检查它是否能够将输入转换为int。如果是的话，一切都好，其他的错误将是打印，但程序不会崩溃。

        // Creates a "scanner" for the input
        Scanner readInput = new Scanner(System.in);

        // Print out random integer and open close message.
        System.out.println("Printing Random Numbers between 1-200: ");
        try {
            int guess = readInput.nextInt();
        } catch (InputMismatchException e) {
            System.err.println("You didn't enter a number.");
        }