Why isn't my code printing?

Question about the task

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I keep getting a number format exception on my parseInt areas of code, saying that I am trying to convert null to an int. I input number in the input area of the screen, why won't it read my input?

Write a program that:
1. reads a number N (must be greater than 0) from the console
2. reads N numbers from the console
3. Displays the maximum of the N entered numbers.

Requirements:

The program should read the numbers from the keyboard.
The program must display a number on the screen.
The class must have a public static void main method.
Don't add new methods to the Solution class.
The program should display the maximum of the N entered numbers.
The program should not display anything if N is less than or equal to 0.

package com.codegym.task.task05.task0532; import java.io.*; /* Task about algorithms */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int maximum = Integer.MIN_VALUE; int N = Integer.parseInt(reader.readLine()); while(N>0){ int r = Integer.parseInt(reader.readLine()); if(r>maximum){ r = maximum; } } System.out.println(maximum); } }

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Darshan Jamgade

Level 9 , Masinigudi, India

26 June 2019, 12:37

BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int count = 0; int maximum = Integer.MIN_VALUE; int N = Integer.parseInt(br.readLine()); while (count < N) { int x = Integer.parseInt(br.readLine()); if(x > maximum) maximum = x; count++; } System.out.println(maximum);

Mahmudjon Omonov

Level 8 , Tashkent, Uzbekistan

26 June 2019, 05:10

int N = Integer.parseInt(reader.readLine()); int maximum = Integer.parseInt(reader.readLine()); for(int i = 1; i <= N-1; i++){ int r = Integer.parseInt(reader.readLine()); if(r > maximum) maximum = r; }

Vlad Tifrea

Level 15 , Bucharest, Romania

25 June 2019, 13:41

Not really sure about this , but one problem could be that since you are using INTEGER.parseInt... for N ad r, you are giving the first value from the console to N and the list of numbers from which you need to determine the minimum is one number short.

Kimo Kalilikane

Level 15 , Jacksonville, United States

25 June 2019, 13:31

useful

There is a logic issue with your while loop. The r variable is created within the loop, therefore it can only exist within that loop. Additionally, your maximum value is never updated after it is first initialized. Try thinking about it this way 1) Get a number that is entered by the user (should be greater than 0). This number will indicate the total entries the user can enter. 2)Continue to read numbers from the keyboard. With each entry compare its value with the previous stored value and if it is greater replace it otherwise continue. 3)Once all numbers have been read from the keyboard display the highest value.

Mikayla Pace Frontend Developer at Malouf Home

26 June 2019, 13:00

I flipped my if statement around to update the maximum value

if(input>maximum){
                maximum = input;
            }

Additionally, I added a counter since the while loop was never decrementing Ns value, so it wouldn't run through properly.

int count =0;

        while(count<N){
            int input = Integer.parseInt(reader.readLine());
            if(input>maximum){
                maximum = input;
            }
            count++;
        }

It works now, thank you!

Kimo Kalilikane

Level 15 , Jacksonville, United States

27 June 2019, 18:24

Great! I'm glad you were able to fix your issues and got the code to work.