Scanner won't remember the previously entered integer

Question

I am trying to program a basic calculator which takes two numbers and adds them. First it assumes the entered numbers are integer if not, it throws and catches an exception and assumes the entered input is double. The program works fine unless the first entered number is integer and the second is double it just hangs and does nothing.

        /* Reads two numbers. Assuming the entered input is integer, Adds
         * the numbers and prints out the result If not integer, throws an
         * InputMismatchException.*/

        Scanner inputSource = new Scanner(System.in);

        try 
        {
            Integer input1, input2, result;

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

            result = input1 + input2;

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

        catch (java.util.InputMismatchException e) 
        {

            double input1, input2, result;

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

            result = input1 + input2;


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

`"Scanner won't remember the previously entered integer"` -- the Scanner is not supposed to *remember* **anything**. — Hovercraft Full Of Eels, Sep 20 '15 at 21:51
When the second input is an Integer, it'll throw an exception and wait for you two input two doubles. Waiting for input is not "hanging". — azurefrog, Sep 20 '15 at 21:53
@azurfrog you're right I just tested that. But how will it take the previously entered integer as a double? Example: If I enter 7 and 8.5 — Farooq Khan, Sep 20 '15 at 21:56
What if the user writes a String or a float? How are you going to catch the exception from the catch itself and so on? — Yassin Hajaj, Sep 20 '15 at 21:59

score -1 · Answer 1 · answered Sep 20 '15 at 22:02

If i am interpreting your problem correctly when you enter a double as the second number it is entering the catch block of your statement and thus you need to enter a second number. To fix this you need to separate your nextInt() method calls to check for doubles instead of having them in the same try catch block, then you should use logic to decide which two values to add together.

Scanner won't remember the previously entered integer

1 Answers1