Why the arithmetic mean result is not correct in my code?

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Hello! Why the arithmetic mean result is not correct in my code? Thanks a lot! package com.codegym.task.task05.task0507; /* Arithmetic mean */ import java.io.*; public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader (new InputStreamReader(System.in)); int sum = 0; int count = 0; int number = Integer.parseInt(reader.readLine()); while (number != -1) { double avg = 0; number = Integer.parseInt(reader.readLine()); sum += number; count++; if (number == -1) { avg = sum / count; System.out.println(avg); break; } } } }

Use the keyboard to enter numbers, and then calculate the arithmetic mean.
If the user enters -1, display the arithmetic mean of all entered numbers and end the program.
-1 should not be included in the calculation.

Here are some examples:
a) if you enter the numbers
1
2
2
4
5
-1
then we display
2.8

b) if you enter the numbers
4
3
2
1
-1
then we display
2.5

Hint: one of the solutions to this problem uses the following construct:

while (true) {
    int number = read the number;
    if (check whether the number is -1)
        break;
}

Requirements:

The program must read data from the keyboard.
The program should display data on the screen.
After entering -1, the program must correctly terminate.
If you sequentially enter the numbers 1, 2, 2, 4, 5 and -1, the program should display 2.8.
If you sequentially enter the numbers -100, 0, 100, and -1, the program should display 0.0.
If you sequentially enter the numbers 1 and -1, the program should display 1.0.
The displayed result should match the task conditions for any input data.

package com.codegym.task.task05.task0507; /* Arithmetic mean */ import java.io.*; public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader (new InputStreamReader(System.in)); int sum = 0; int count = 0; int number = Integer.parseInt(reader.readLine()); while (number != -1) { double avg = 0; number = Integer.parseInt(reader.readLine()); sum += number; count++; if (number == -1) { avg = sum / count; System.out.println(avg); break; } } } }

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Misiu

Level 41 , Gdansk, Poland

4 November 2020, 15:46

int / int ---> int

Cristian

Level 13 , Ploiesti, Romania

4 November 2020, 16:07

Okay! Thanks!

Switch/Cypher

Level 25 , Bexleyheath, United Kingdom

4 November 2020, 11:25

It's because you aren't adding the result of the first number you enter to sum.

int sum = 0;
      int count = 0;
      int number = Integer.parseInt(reader.readLine()); // You set a number here

      while (number != -1) {
          double avg = 0;
          number = Integer.parseInt(reader.readLine()); // But then you overwrite that variable
          sum += number; // and it doesn't get included
          count++;
          if (number == -1) {
              avg = sum / count;
              System.out.println(avg);
              break;
          }
      }

Cristian

Level 13 , Ploiesti, Romania

4 November 2020, 15:40

Hi, Cypher! I have written code in this way int sum = 0; int count = 0; double avg = 0; double number = 0; while (true) { number = Integer.parseInt(reader.readLine()); if (number == -1) { break; } sum += number; count++; avg = sum / count; } System.out.println(avg); Two warnings! 1. If you sequentially enter the numbers 1, 2, 2, 4, 5 and -1, the program should display 2.8. 2. The displayed result should match the task conditions for any input data. What is wrong? Thank you very much!

Switch/Cypher

Level 25 , Bexleyheath, United Kingdom

4 November 2020, 16:36

"sum" needs to be a double. Because! Even though "avg" is a double, the remainder will still be ignored because you are dividing int by int.

Switch/Cypher

Level 25 , Bexleyheath, United Kingdom

4 November 2020, 16:40

public static class Solution {

       static double sum = 0;
       static int count = 0;
       static double avg = 0;
       static double number = 0;

       public static void main(String[] args) throws IOException {

           BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

           while (true) {
               number = Integer.parseInt(reader.readLine());
               if (number == -1) {
                   break;
               }
               sum += number;
               count++;
               avg = sum / count;
           }
           System.out.println(avg);
       }
   }

Cristian

Level 13 , Ploiesti, Romania

4 November 2020, 18:21

I see, Chypher! Thank you so much!