Giving the inputs satisfies the conditions but verification fails

Question about the task

Under discussion

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.util.*; public class Solution { public static void main(String[] args) throws Exception { //write your code here Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int []a = new int[n]; double sum = 0; double mean = 0; for (int i=0; i < n; i++) { a[i] = sc.nextInt(); if (a[i] != -1) { sum = sum + a[i]; } if (a[i] == -1) { mean = sum/(n-1); break; } } System.out.println(mean); } }

Comments (4)

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Okanlawon Oluwatobi Damilare

Level 9 , Banjul, Gambia

25 March 2019, 19:37

use double instead of int

Satya Vath

Level 31 , Vijayawada, India

22 March 2019, 14:28

//use this bro
package com.codegym.task.task05.task0507;

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

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class Solution {
    public static void main(String[] args) throws Exception {
        //write your code here
        BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<Double> list = new ArrayList<Double>();
        while(true){
            double a = Double.parseDouble(buf.readLine());
            if (a == -1){
                break;
            }
            else{
                list.add(a);
            }
        }
        double j = 0;
       for (Double s : list){
           j = j + s;
       }
       double y = list.size();
       double d = j / y;
       System.out.println(d);
    }
}

Jeff

Level 6 , Taco Town, United States

16 October 2019, 18:37

Can you briefly explain line 34?

for (Double s : list){

This is my first time in the course seeing ArrayList used, or a colon for that matter.

Guadalupe Gagnon

Level 37 , Tampa, United States

13 March 2019, 20:40

The task says to accept user inputs until -1 is entered and then display the mean. Your first problem is that you are setting an amount of inputs to n when the problem does not call for that. If you tried to enter the first example [1,2,2,4,5,-1] the program would stop after the first 2 was entered and display 0.0 because the program only calculates mean inside the for loop after -1 is entered. You need to fix all of these.