Java program to read user input numbers with blank spaces

Java program to read user input numbers with blank spaces:

In this post, we will learn how to get user-input numbers with blank spaces and add them to an array. We will assume that the input will include only numbers with blank spaces. I will show you different ways to solve this.

Method 1: By using a loop:

If we know the total count of numbers, we can use a loop to read the numbers to an array. For example:

import java.util.Arrays;
import java.util.Scanner;

public class Example {
    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            System.out.println("Please enter three numbers with space:");

            int[] intArray = new int[3];
            for (int i = 0; i < 3; i++) {
                intArray[i] = scanner.nextInt();
            }

            System.out.println("You have entered: " + Arrays.toString(intArray));
        }
    }
}

Download it on GitHub

Here,

The program assumes that the user will always enter three numbers, separated with space.
It created one Scanner object to read the user input values.
It initialized an integer array intArray of size 3 to hold the numbers.
The for loop runs from i = 0 to i = 3 and on each iteration, it uses the nextInt() method to read the integers. It assigns the numbers to the intArray.
The last line is printing the values of the intArray.

If you run this program, it will print outputs as below:

Please enter three numbers with space:
22 34 4
You have entered: [22, 34, 4]

We can also enter more than three numbers, but it will read only the first three numbers:

Please enter three numbers with space:
22 34 4 55 67
You have entered: [22, 34, 4]

Method 2: By split the string:

The above program will work if we know the total count of numbers the user will enter. If we don’t know the count, we can read the input as a String and split it to get the numbers. The following example program shows how we can read any amount of user input numbers:

import java.util.Arrays;
import java.util.Scanner;

public class Example {
    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            System.out.println("Please enter the numbers separated with space:");

            String numString = scanner.nextLine();
            String[] nums = numString.split(" ");

            int[] intArray = new int[nums.length];

            for (int i = 0; i < nums.length; i++) {
                intArray[i] = Integer.parseInt(nums[i]);
            }

            System.out.println("You have entered: " + Arrays.toString(intArray));
        }
    }
}

Download it on GitHub
The scanner variable is using the nextLine() method to read all the numbers as a string and assigns this value to the numString variable.
The split() method will break the string around white spaces and return one array holding the numbers as strings. It is assigned to the nums variable.
The integer array intArray is initialized with a length equal to the list nums.
The for loop is iterating over the elements of the array nums. On each step, it uses the Integer.parseInt function to convert the character at ith position of the nums array to integer and assigns it to the ith element of the intArray.
The last line is printing the elements of the array intArray.

If you run this program, it will print outputs as below:

Please enter the numbers separated with space:
1 2 3
You have entered: [1, 2, 3]

Please enter the numbers separated with space:
1 2 3 4 5
You have entered: [1, 2, 3, 4, 5]

It will work with any number of elements.

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Java program to read user input numbers with blank spaces