如何从扫描仪获取多个整数输入并将每个整数存储在单独的数组中？

Question

I'm trying to create a program which allows the user to addition as many pairs of numbers as they would like, by first taking user input to ask them how many sums they would like to complete (additions of 2 numbers), thereafter creating 2 arrays of whatever size the user has input, and then asking the user to input each pair of numbers on a single line that they would like to addition and storing the first value in one array and the second value in a second array from each input. This is where I am stuck, I don't know how I can take the user input as two int values on each line and store them in the respective indexes of each array to be added later. Please take a look at my code below:

import java.util.Scanner;

public class SumsInLoop {

public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);

    System.out.println("Enter the amount of sums you would like to calculate: ");
    int n = sc.nextInt();

    int a[] = new int[n];
    int b[] = new int[n];

    String[] input = new String[2];
    System.out.println("Please enter the values you would like to sum as pairs of two numbers: ");
    for (int i = 0; i < a.length; i++) {
        input = sc.nextLine().split(" ");
            int[] intinput = Arrays.asList(input).stream().mapToInt(Integer::parseInt).toArray();
a = intinput[0];
b = intinput[1];
}
}

Answer 1

I think you need to change 2 lines this way:

a[i] = intinput[0];
b[i] = intinput[1];

Answer 2

Just read pairs with nextInt() method of scanner, it's use all space symbols like separator (not only end of line):

public class SumsInLoop {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the amount of sums you would like to calculate: ");
        int n = sc.nextInt();

        int a[] = new int[n];
        int b[] = new int[n];

        System.out.println("Please enter the values you would like to sum as pairs of two numbers: ");
        for (int i = 0; i < a.length; i++) {
            a[i] = sc.nextInt();
            b[i] = sc.nextInt();
        }
    }
}

Answer 3

You're using nextLine() method, which is useful for string input, but it's not the best solution for integer or other primitive data.

In addition, this line of code is wrong :

a = intinput[0];

because you're storing an integer value as integer array. You must store that value inside a[i] in order to respect the variables type.

I'd do it this way:

public class SumsInLoop {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the amount of sums you would like to calculate: ");
        int n = sc.nextInt();

        int a[] = new int[n];
        int b[] = new int[n];

        for (int i = 0; i < a.length; i++) {
            System.out.println("Please enter the values you would like to sum as pairs of two numbers: ");
            // Read pair and store it inside i-th position of a and b arrays 
            System.out.println("Enter first number: ");
            a[i] = sc.nextInt();
            System.out.println("Enter second number: ");
            b[i] = sc.nextInt();
        }
        // Close scanner
        sc.close();

        // Prints every sum
        for(int i = 0; i < a.length; i++){
            System.out.println(i + "-th sum is: " + (a[i] + b[i]));
        }
    }
}

Here you read every pair with nextInt() which is specific for integer data.

Every time you store items in i-th position of arrays, so finally you can sum a[i] and b[i] .

Result example:

Enter the amount of sums you would like to calculate: 
4
Please enter the values you would like to sum as pairs of two numbers: 
Enter first number: 
2
Enter second number: 
1
Please enter the values you would like to sum as pairs of two numbers: 
Enter first number: 
3
Enter second number: 
4
Please enter the values you would like to sum as pairs of two numbers: 
Enter first number: 
5
Enter second number: 
6
Please enter the values you would like to sum as pairs of two numbers: 
Enter first number: 
7
Enter second number: 
8
0-th sum is: 3
1-th sum is: 7
2-th sum is: 11
3-th sum is: 15