Java: Random Class Advice

Question

So I'm supposed to create a program that generates 100 random integers between 1 and 1000, and then tell the number of integers that returned even and odd. I've got that part down so far. The second part I can't figure out, however. I need to do the same thing 10 times, and then I need to add all of those together to get a total.

import java.util.Random;

public class EvenOrOdd
{
  public static void main(String[] args)
  {
    int even = 0, odd = 0;
    int iteration = 0;

    while (iteration<10)
    {
      for(int i = 0; i<100;i++)
      {
        int number2 = random.nextInt(1000) + 1;
        if ((number2 % 2) == 0)
        {
          even++;
        }
        else if ((number2 % 2) == 1)
        {
          odd++;
        }

      }
      System.out.println("Iteration " + " Evens " + " Odds");
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "          " + even + "     " + odd);
        iteration++;
      System.out.println(iteration + "         " + even + "     " + odd);
    }
    System.out.println("\nEvens: " + even + "\nOdds:  " + odd);
  }
}

I've tried taking out the

System.out.println("Iteration " + " Evens " + " Odds");

and placing it above the while-loop, and then removing all but one of the

    iteration++;
  System.out.println(iteration + "          " + even + "     " + odd);

But when I do that, my evens and odds nearly double each iteration.

So to repeat what I want to do again: I want to make it so each

    iteration++;
  System.out.println(iteration + "          " + even + "     " + odd);

displays a new even and odd, and not the same one. And then, since I am not sure how to do this either, I want to total up the ten evens and the ten odds. Thanks for any help!

Answer 1

You were almost there, the main problem is that you increment iteration 10 times inside the while-loop, so it drops out of the while-loop immediately. I just removed all those increments, and it works!

Furthermore it can be an idea to have a total counter of the even and odd numbers outside the while-loop, and then add up the total after each iteration in your while-loop, as following:

public class EvenOrOdd {

    public static void main(String[] args) {

        Random random = new Random();
        int evenTotal = 0, oddTotal = 0;
        int iteration = 0;

        System.out.println("Iteration " + " Evens " + " Odds");

        while (iteration < 10) {
            int even = 0, odd = 0;
            for (int i = 0; i < 100; i++) {
                int number2 = random.nextInt(1000) + 1;
                if ((number2 % 2) == 0)
                    even++;
                else if ((number2 % 2) == 1)
                    odd++;

            }
            iteration++;
            System.out.println(iteration + "          " + even + "     " + odd);
            evenTotal += even;
            oddTotal += odd;
        }
        System.out.println("\nEvens: " + evenTotal + "\nOdds:  " + oddTotal);
    }

}