當用戶可以輸入int和double時添加兩個數字

Question

我需要程序在用戶輸入例如4和6.5時運行，反之亦然。 我有if else只在其中的任何一個或當它試圖同時運行它時，我得到一個像這樣的錯誤代碼：

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)

任何幫助將不勝感激

    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

在這種情況下，使用double number = Double.parseDouble(inputSource.nextLine());讀取輸入更有意義double number = Double.parseDouble(inputSource.nextLine()); 。 這適用於int和double輸入。

您的代碼變得如此簡單：

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

除此之外，改變while (answer != "N"); to while (!answer.equals("N")); 。

Answer 2

使用nextLine()方法而不是nextInt()並將其解析為double，這將適用於int和double類型

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

並且同時改變while (answer != "N"); with while (!answer.equals("N"));// since your are comparing string not character