CodeGym/Help with Java Tasks/What am I missing?

Level 24

Phoenix

26.03.2019
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12comments

What am I missing?

Question about the task

Resolved

This will output the correct answer for the test input in the conditions and anything else I have thrown into it. I take into account possible negative numbers entered by the user, and it outputs the correct answer, but I keep getting told the "displayed text must match the task conditions." The commented out lines on the bottom also apparently will not match the task conditions. The displayed text looks like the task conditions, I even copied and pasted it into the solution to make sure I'm not missing spaces or anything. What is it that I am not seeing?

Use the keyboard to enter a positive number. Determine the number of even digits and odd digits in the entered number.
If a number is divisible by 2 without a remainder (i.e. the remainder is zero), then it is even.
And we'll increase the even digit counter (static variable even) by 1.
Otherwise, the number is odd, so we'll increase the odd digit counter (static variable odd).
Display the following message: "Even: a Odd: b", where a is the number of even digits and b is the number of odd digits.

Example for 4445:
Even: 3 Odd: 1

Requirements:

The program must read data from the keyboard.
The main method should calculate how many even digits are in the entered number and then write this number to the variable even.
The main method should calculate how many odd digits are in the entered number and then write this number to the variable odd.
The program should display text on the screen.
The displayed text must match the task conditions.

package com.codegym.task.task06.task0606; import java.io.*; /* Even and odd digits */ public class Solution { public static int even; public static int odd; public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String strN = reader.readLine(); int n = Integer.parseInt(strN); if (n < 0) n *= -1; for (int i = 1; i < n; i *= 10) { int m = n / i; if (m % 2 == 0) even++; else odd++; } //System.out.print("Even: " + even + " " + "Odd: " + odd); //System.out.println("Even: " + even + " " + "Odd: " + odd); //System.out.print("Even: " + even + " Odd: " + odd); System.out.println("Even:" + " " + even + "Odd:" + " " + odd); //System.out.println("Even: " + even + " Odd: " + odd); } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

26 March 2019, 14:01

Your output is incorrect. Check with the example and make corrections. (there is a missing space). Also, there is no reason to use static variables in this exercise. It is bad practice to use static variables when they are not called for either way. I would recommend changing even and odd to local variables.

Sean

Level 24 , Phoenix, United States

26 March 2019, 16:29

Yeah, I was getting irritated and was trying every possible permutation with the spaces, and the one I left for the code example was missing a space. I have to use the static variables on this task, otherwise two of the conditions aren't met. When I run without verification this is my output:

There are no leading or trailing spaces. The program outputs correctly with negative numbers entered. I don't see how that is different from the expected output format in the conditions.

Guadalupe Gagnon

Level 37 , Tampa, United States

26 March 2019, 17:23

My bad, i didn't notice that the task actually required using the static variables, forget that part of my last post. A problem i now see is that you are having the loop counter i start at 1. If the user enters 1 the code will output: Even: 0 Odd: 0 where the Odd should be 1. I don't think that you need to consider the case where the user input is just 0, though my code that passed did. Message me after trying to account for what I mentioned if you still are having trouble and I will share my solution.

Sean

Level 24 , Phoenix, United States

26 March 2019, 21:55

Thank you!!! That was it, my for loop logic wouldn't count 1 as odd or even if that was the input. Thanks for your help!

dean

Level 8 , Deutschland, Germany

25 April 2019, 11:34

hey can you explain line 21? i understand that line 19 is to turn negative number to positive, but why you multiply i each time by 10 and then divide it each time in the loop? im confused about the idea here.. thanks

Sean

Level 24 , Phoenix, United States

26 April 2019, 23:08

I'm essentially getting rid of the last digit each time through after testing whether it is odd or even and adding it to the counts. Using the test case in the conditions (n = 4445), this is what my code is doing: First time through the for loop: m = 4445 / 1, which is 4445, then i check if the number is odd or even (odd, and add it to the appropriate count) Second time through: i now equals 10 so m = 4445 / 10, which in integer division in Java is 444, check if that's odd or even, etc. Third time: i = 100, m = 4445 / 100, which is 44 Fourth: i = 1000, m = 4445 / 1000, which is 4. After the fourth time, the for loop exits because 1000 * 10 is greater than n (4445). I hope that helps.

dean

Level 8 , Deutschland, Germany

4 May 2019, 06:55

thanks makes sense! though how do you make it work with number 0 (even) as well in the loop? edit: nevermind i figured it just add another if statement before the loop to check if number input is 0 :)

Gugun

Level 11 , Bogor, Indonesia

11 May 2019, 01:22

I just wondering what if the conditions (n = 10 or 100, and so on)?

Sean

Level 24 , Phoenix, United States

11 May 2019, 01:44

It would count the 0's as even, which I think would satisfy the conditions for this specific task, even though that is not technically correct looking at it strictly from a mathematical point of view (0 is neither odd nor even). The task conditions define an even number as: "If a number is divisible by 2 without a remainder (i.e. the remainder is zero), then it is even." 0 % 2 = 0 in Java. So, technically speaking, they should have a third static variable that counts zeros if they wanted to be mathematically correct, but at this point in the quest I think they're trying not to over complicate things and get you working with static variables and practicing loops.

dean

Level 8 , Deutschland, Germany

18 May 2019, 04:28

thanks totally makes sense, i've a question about a differnet code because i really liked your clear simple explanation:

public class Solution {
    public static void main(String[] args) {
        for(int i=1; i<=50000; i++){
            Cat cat = new Cat();
            Dog dog = new Dog();// write your code here
        }
    }
}

In the code above,how come it doesn't override the same cat & dog objects names? how it creates 50k with the same name? just curious about the technical functionality behind this, i mean how it's possible..

senthamil

Level 18 , Korampallam, India

18 May 2019, 05:23

public class Solution { public static void main(String[] args) { for(int i=1; i<=50000; i++){ Cat cati = new Cat(); Dog dogi = new Dog();// write your code here } } }

dean

Level 8 , Deutschland, Germany

20 May 2019, 08:27

those create just 1 object 50k times and override the older ones i was asking (but i also asked the same question in the other post so you can answer on either of them.. also a question regardless, in the code below, when the code goes to the next string, when the code know to move to the next var is it one digit/letter per string variable or?

public class MainClass
{
  public static void main(String[] args) throws IOException
  {
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    String[] list = new String[10];

    for (int i = 0; i < list.length; i++)
    {
      list[i] = reader.readLine();
     }
  }