How to take n input in java according to the value of test cases?

Question

How can we take n input in java according to value of T

Like if i take t=2,then we take two n input

If value of t=3,then we take three n input

import java.util.Scanner;

public class Main {
     public static void main(String[] args){
         Scanner s= new Scanner(System.in);
         int t=s.nextInt();

         int n=s.nextInt();
         int n=s.nextInt();

         int evensum=0;

         for (int i=1; i<=n; i++) {
             if(i%2==0) {
                 evensum=evensum+i;
             }
             System.out.print(evensum);
         }
    }

As in this code i take t=2 and I take two n inputs. If I take t=3, then what how could I take that third input?

You can't have multiple variables with the same name. make an array or a list to store your inputs. — Amongalen, Mar 23 '20 at 10:21
Krishan - If one of the answers resolved your issue, you can help the community by marking it as accepted. An accepted answer helps future visitors use the solution confidently. Check https://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work to learn how to do it. — Arvind Kumar Avinash, May 19 '20 at 21:46

score 0 · Answer 1 · answered Mar 23 '20 at 10:24

You can't have multiple variable with the same name, for your purpose use a loop :

Scanner s = new Scanner(System.in);
System.out.println("How many values ?");
int nbInput = s.nextInt();
for (int i = 1; i <= nbInput; i++) {
    int input = s.nextInt();
    System.out.print(input);
}

score 0 · Answer 2 · answered Mar 23 '20 at 10:50

Whenever you assign a new value to a variable, the new value replaces the old value in it. In other words, there can be only one value in a variable. In case of an array, you can have multiple values assigned to array variables (identified by their indexes) but keep in mind that the array name itself can refer to only a single value.

Another thing you should keep in mind is the problems associated with Scanner::next, Scanner::nextInt etc. when you are inputting value in a loop. Check this to learn more about it.

Considering the points mentioned above, a better way to handle such a requirement would be as follows:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        boolean valid;
        int t = 0, n = 0;
        do {
            valid = true;
            System.out.print("Enter the number of integers you want to process: ");
            try {
                t = Integer.parseInt(s.nextLine());
                if (t < 0) {
                    System.out.println(
                            "Error: This is a wrong input. The number should be a positive integer. Try again.");
                    valid = false;
                }
            } catch (NumberFormatException e) {
                System.out.println("Error: This is a wrong input. The number should be a positive integer. Try again.");
                valid = false;
            }
        } while (!valid);

        System.out.println("Thank you. Now enter " + t + " intgers as prompted.");
        int evensum = 0;
        for (int i = 1; i <= t; i++) {
            do {
                valid = true;
                System.out.print("Enter an integer: ");
                try {
                    n = Integer.parseInt(s.nextLine());
                    if (n % 2 == 0) {
                        evensum = evensum + n;
                    }
                } catch (NumberFormatException e) {
                    System.out.println("Error: This is a wrong input. Try again.");
                    valid = false;
                }
            } while (!valid);
        }

        // Display the result of adding all even inputs
        System.out.print("The sum of even integers input by you is " + evensum);
    }
}

A sample run:

Enter the number of integers you want to process: 3
Thank you. Now enter 3 intgers as prompted.
Enter an integer: 10
Enter an integer: 5
Enter an integer: 8
The sum of even integers input by you is 18

Another sample run:

Enter the number of integers you want to process: a
Error: This is a wrong input. The number should be a positive integer. Try again.
Enter the number of integers you want to process: 10.5
Error: This is a wrong input. The number should be a positive integer. Try again.
Enter the number of integers you want to process: -20
Error: This is a wrong input. The number should be a positive integer. Try again.
Enter the number of integers you want to process: 3
Thank you. Now enter 3 intgers as prompted.
Enter an integer: 10
Enter an integer: xyz
Error: This is a wrong input. Try again.
Enter an integer: 1.5
Error: This is a wrong input. Try again.
Enter an integer: 5
Enter an integer: 8
The sum of even integers input by you is 18

Feel free to comment in case of any issue/doubt.

How to take n input in java according to the value of test cases?

2 Answers2