java - 当用户可以输入 int 和 double 时添加两个数字

Question

当用户输入例如 4 和 6.5 时，我需要运行该程序，反之亦然。 我仅在其任一或或时运行 if else，当它尝试同时运行两者时，我收到如下错误代码:

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 class2.AddTwoNumbers.main(AddTwoNumbers.java:28)

任何帮助将不胜感激

    public class AddTwoNumbers {

        public static void main(String[] args) {
    Scanner inputSource = new Scanner(System.in);
    Scanner runAgain = new Scanner(System.in);
    int input1, input2, result;
    double input3, input4, result2;

    String answer = null;

    do {

         System.out.println("Please enter two numbers: ");
    if(inputSource.hasNextInt()) {

      input1 = inputSource.nextInt();
      input2 = inputSource.nextInt();


      result = input1 + input2;
      System.out.println("The sum of " + input1 + " and " + input2 + " is " + result);

       } else if (!inputSource.hasNextInt()){

              input3 = inputSource.nextDouble();
              input4 = inputSource.nextDouble();

              result2 = input3 + input4;
              System.out.println("The sum of " + input3 + " and " + input4 + " is " + result2);

              } else if (inputSource.hasNextInt() ||   inputSource.hasNextDouble()){
                  input1 = inputSource.nextInt();
                  input3 = inputSource.nextDouble();

                  result2 = input1 + input3;
                  System.out.println("The sum of " + input1 + " and " + input3 + " is " + result2);
    }           
    System.out.println("Do you want to run this again? Enter Y for Yes or N for No: ");
             answer = runAgain.next();


           } while (answer != "N");

           inputSource.close();     
     }

}

Answer 1

在这种情况下，使用 double number = Double.parseDouble(inputSource.nextLine()); 读取输入更有意义。这适用于 int 和 double 输入。

您的代码变得如此简单:

double input1 = Double.parseDouble(inputSource.nextLine());
double input2 = Double.parseDouble(inputSource.nextLine());
double result = input1 + input2;

除此之外，将 while (answer != "N"); 更改为 while (!answer.equals("N"));。