Confusion About The Min Value Of Integers

Question about the task

Resolved

In the official code given by codegym, the max variable is assigned with the min value for an integer. But I don't understand why ?

int max = Integer.MIN_VALUE; //max variable being intialized as the min value of integer
while (console.hasNextInt()) {
    int x = console.nextInt();
    if (x % 2 == 0 && x > max) {
        max = x;
    }
}

In my code below, I assign the value 0, to the variable, maxNumber but not the min value for an integer. Thats why I don't fulfill the fifth requirement but I still don't understand. Can someone explain to me why the maxNumber variable should be assigned with min value for an integer ?

The program must read integers from the keyboard until something else is entered, such as a string or a character. Display the maximum even number entered. If several numbers are entered, you must display any of them.

Example input:

Example output:
8

Requirements:

The program should read numbers from the keyboard.
The program should display a number on the screen.
The program should display the maximum even number of the integers entered.
If several maximum even numbers are entered, then you need to display any one of them.
If there is no even number among the entered characters, or only one non-numeric character is entered, then display the minimum possible value for an int.
You need to read data from the keyboard in a while loop.

package en.codegym.task.pro.task04.task0408; import java.util.Scanner; /* Maximum of entered numbers */ public class Solution { public static void main(String[] args) { //write your code here Scanner keyboardInput = new Scanner(System.in); int maxNumber = 0; while (keyboardInput.hasNextInt()) { if (keyboardInput.nextInt() % 2 == 0) { if (keyboardInput.nextInt() > maxNumber) { maxNumber = keyboardInput.nextInt(); } } } System.out.print(maxNumber); } }

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Thomas

Level 41 , Bayreuth, Germany

16 March, 14:48

solution

let's say you want to find the max of an entered number between -10 and 10 Then you arbitrary initialize the max with 0 and set the entered number to -4. If you now compare the input with the max, then the max already is greater than your input and your program would spit out zero as the result, the maximum. To get a correct result you'd need to set max to the minimum possible number -10 (if there is at least one input).

PQK

Level 6 , United States of America, Sweden

20 March, 06:34

package en.codegym.task.pro.task04.task0408;

import java.util.Scanner;

/*
Maximum of entered numbers
*/

public class Solution {
    public static void main(String[] args) {
        //write your code here

        Scanner keyboardInput = new Scanner(System.in);

        int maxNumber = Integer.MIN_VALUE;

        while (keyboardInput.hasNextInt()) {

                if (keyboardInput.nextInt() % 2 == 0) {
                    if (keyboardInput.nextInt() > maxNumber) {
                        maxNumber = keyboardInput.nextInt();
                    }

                }
            }

            System.out.print(maxNumber);
        }
    }

Now I have another problem. After I amend my code, put the maxNumber variable to Integer.MIN_VALUE, and verify my code, the first 4 requirements were not met which I should have fulfillled ?? Whats wrong with the code ?

Thomas

Level 41 , Bayreuth, Germany

20 March, 11:32

useful

Scanner.hasNextInt() checks if there is a next token in the input stream and if the next token is an int. Scanner.nextInt() removes (if any exists) the next token (if it is an int) from the input stream. The next thing you need to know is that Scanner methods may block. Means your program stops till there is an input. So let's look at your code. line 17: while (keyboardInput.hasNextInt()) { Scanner blocks till there is an input. If you made an input and it is an int, the program continues inside the loops body, if it is not an int, it leaves the loop. Good. line 19: if (keyboardInput.nextInt() % 2 == 0) { Scanner.nextInt() removes the next integer from the input stream. If the input was 4, then you can substitute the method call with 4 like: if (4 % 2 == 0) { This results in true and you continue with line 20: if (keyboardInput.nextInt() > maxNumber) { Scanner.nextInt() tries to remove the next integer from the input stream. However most probably the input stream is empty. You emptied it in line 19. So Scanner.nextInt() blocks waiting for you to enter the next int. That's not what you intended to do, you wanted to use the value from the method call in line 19 line 21: maxNumber = keyboardInput.nextInt(); Same here, your program blocks till you enter the next integer. But you do not want to work with a newly entered int but instead to use the value from line 19.

PQK

Level 6 , United States of America, Sweden

21 March, 13:00

Ok thank you very much 😁