Java do while loop not looping

Question

I'm having a bit of trouble with this do while loop. The system will print out the line and stop. What am I doing wrong? Thank you for your time!

Scanner keyboard = new Scanner(System.in);

    String answer;
    int inputNum = 1;
    int countOdd = 0;
    int countEven = 0;

    do{
        do{
            System.out.println("Please enter an interger. When you are finished, enter 0.");
            inputNum = keyboard.nextInt();

                while (inputNum % 2 == 0)
                    countOdd++;
                while (inputNum % 2 != 0)
                    countEven++;
        }while(inputNum != 0);


        System.out.println("Thank you. The amount of odd intergers you entered is " 
        + countOdd + ". The amount of even intergers you entered is " + countEven);


        System.out.println("Thank you. The amount of odd intergers you entered is " 
        + countOdd + ". The amount of even intergers you entered is " + countEven);

        System.out.println("Would you like to run this program again? (Y) (N)");
        answer = keyboard.nextLine();

    }while (answer.equals("Y"));

    System.out.println("Thank you!");
}

}

Never heard of a do loop, only a do while loop. Where's the while? — mmking
– mmking, Commented Oct 4, 2015 at 23:09
"The system will print out the line and stop" So what is it printing and what is your expected output? — user3437460
– user3437460, Commented Oct 4, 2015 at 23:14
Possible duplicate of Skipping nextLine() after using next(), nextInt() or other nextFoo() methods — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Oct 4, 2015 at 23:18
... After seeing @BalwinderSingh's answer, I see nextLine isn't the problem. (But it will be your next problem after you fix the while/if problem) — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Oct 4, 2015 at 23:19

Orest Hera · Accepted Answer · 2015-10-04 23:17:32Z

4

The following loops cannot be finished, since inputNum is not changed inside:

          while (inputNum % 2 == 0)
                countOdd++;
          while (inputNum % 2 != 0)
                countEven++;

You need if statements here instead of while.

answered Oct 4, 2015 at 23:17

Orest Hera

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Comments

App Work · Accepted Answer · 2015-10-04 23:25:20Z

2

You need to change while with if. The logic inputNum%2==0 checks for even not odd.But if you did it intentionally opposite ,its fine. I changed it as it should be.

        Scanner keyboard = new Scanner(System.in);

    String answer;
    int inputNum = 1;
    int countOdd = 0;
    int countEven = 0;


        do{
            System.out.println("Please enter an interger. When you are finished, enter 0.");
            inputNum = keyboard.nextInt();

             if (inputNum % 2 == 0)
                 countEven++;
               if (inputNum % 2 != 0)
                   countOdd++;
        }while(inputNum != 0);


        System.out.println("Thank you. The amount of odd intergers you entered is " 
        + countOdd + ". The amount of even intergers you entered is " + countEven);

edited Oct 4, 2015 at 23:25

answered Oct 4, 2015 at 23:19

App Work

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1 Comment

Amar boi Over a year ago

Why down voting?? its 100% correct answer. Plus the logic is also corrected.

Balwinder Singh · Accepted Answer · 2015-10-04 23:18:11Z

1

The problem is with the following lines of code

while (inputNum % 2 == 0)
                countOdd++;
while (inputNum % 2 != 0)
                countEven++;

You don't use while statements for if conditions. Instead use this

 if (inputNum % 2 == 0)
                    countOdd++;
 if (inputNum % 2 != 0)
                    countEven++;

answered Oct 4, 2015 at 23:18

Balwinder Singh

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