Question

import java.util.Scanner;

public class Example {
    public static void main(String Args[]) {
        Scanner sc = new Scanner("System.in");
        System.out.println("Yntreq (1/2):");
        int y = sc.nextInt();
        switch (y) {
            case 1:
                System.out.println("Duq yntrel eq 1-y");
                break;
            case 2:
                System.out.println("Duq yntrel eq 2-y");
                break;
            default:
                break;
        }

    }
}

当它运行时，eclipse显示此错误

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 Example.main(Example.java:7)

Answer 1

System.in不是字符串！

变化：

Scanner sc = new Scanner("System.in");

为：

Scanner sc = new Scanner(System.in);

Answer 2

删除双引号＆＃34; ＆＃34;来自＆＃34; System.in＆＃34;

Scanner sc = new Scanner(System.in);
instead of
Scanner sc = new Scanner("System.in");

Answer 3

从""移除Scanner sc = new Scanner("System.in"); 即

Scanner sc = new Scanner(System.in);

Answer 4

你在构造函数中传递了无效参数，输入流的构造函数语法是 -

public Scanner(InputStream source)

构造一个新的Scanner，它生成从指定输入流扫描的值。使用底层平台的默认字符集将流中的字节转换为字符。参数： source - 要扫描的输入流

示例：Scanner sc = new Scanner(System.in);

java控制台程序出错

4 个答案: