java - 两个数字的基本加法

Question

这个问题已经有答案了:

Scanner double value - InputMismatchException (2 个回答)

已关闭 6 年前。

很抱歉问了一个简单的问题，但我是个初学者。所以问题是当我将以下代码复制到我的 eclipse 中时，它工作正常。但是当我将变量的类型从 int 更改为 double 时，它​​显示某种错误。请检查一下。

import java.util.Scanner;

class AddNumbers
{
   public static void main(String args[])
   {
      double x, y, z;
      System.out.println("Enter two integers to calculate their sum ");
      Scanner in = new Scanner(System.in);
      x = in.nextDouble();
      y = in.nextDouble();
      z = x + y;
      System.out.println("Sum of entered integers = "+z);
   }
}

顺便说一句，错误如下

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.nextDouble(Unknown Source)
    at AddNumbers.main(AddNumbers.java:10)

这是我刚刚观看的视频教程(https://www.youtube.com/watch?v=ANuuSFY2BbY)我只是尝试复制它

import java.util.Scanner;

class HelloWorld{

    public static void main(String args[]) {
        Scanner bucky = new Scanner(System.in);
        double fnum;
        double snum;
        double answer;
        System.out.println("Enter first number:");
        fnum = bucky.nextDouble();
        System.out.println("Enter second number:");
        snum = bucky.nextDouble();
        answer = fnum+snum;
        System.out.print(answer);
    }

}

我收到以下错误:

Enter first number:
34.6
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.nextDouble(Unknown Source)
    at HelloWorld.main(HelloWorld.java:11)

Answer 1

你看。我得到了正确的答案。所以你必须像他们所说的那样表现出你的想法。

您还可以像下面这样修改代码以使其更强大。

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

class AddNumbers
{
public static void main(String args[])
  {
    double x, y, z;
    System.out.println("Enter two double to calculate their sum ");
    Scanner in = new Scanner(System.in);

    while (true) {
        try {
            x = Double.parseDouble(in.nextLine());
            y = Double.parseDouble(in.nextLine());
            z = x + y;
            System.out.println("Sum of entered double = " + z);
            break;
        } catch (Exception e) {
            System.out.println("Not a double param, please enter again");
            continue;
        }
    }

}

}