java - 数字格式和输入不匹配异常有何不同

Question

当在 Integer 类构造函数中传递字符值而不是整数值时，以下代码将引发 NumberFormatException

class Wrap
{
    public static void main(String...args)
    {
        Integer j=new Integer("s");
        System.out.println(j);
    }
}

当用户输入字符值而不是整数值时，以下代码将抛出 InputMismatchException

import java.util.Scanner;

class User
{
    public static void main(String...args)
    {
        Scanner obj=new Scanner(System.in);
        int i=obj.nextInt();
        int j=obj.nextInt();
        System.out.println("sum of numbers input by user");
        System.out.println(i+j);
    }
}

这两个异常似乎都是在相同的场景中抛出的，那么它们有何不同？

Answer 1

让我们看看这两个异常类的规范:

InputMismatchException 特定于扫描仪。它表示无效类型，不一定是无效数字。 NumberFormatException 特定于尝试将非数字字符串转换为数字。

public class InputMismatchException extends NoSuchElementException

Thrown by a Scanner to indicate that the token retrieved does not match the pattern for the expected type, or that the token is out of range for the expected type.

public class NumberFormatException extends IllegalArgumentException

Thrown to indicate that the application has attempted to convert a string to one of the numeric types, but that the string does not have the appropriate format.