How to Insert an Element in a Java Array at a Specific Position

Insertion-tutorial

In Java, arrays are of fixed size, so inserting an element at a specific position involves shifting elements manually to make space for the new item.
This is a common operation when learning array manipulation in Java.

Insertion of element into an array at a specified position

package QuipoHouse.ArrayOperations;

import java.util.Scanner;

public class Insertion {
    public static void main(String[] args) {
        int arr[] = new int[20];  // Declaring array with max size
        int i;

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the number of elements (less than 20):");
        int n = sc.nextInt();  // Size of array (n elements)

        System.out.println("Enter the elements of the array:");
        for (i = 0; i < n; i++) {
            arr[i] = sc.nextInt();  // Taking input
        }

        System.out.println("Enter the element to insert:");
        int data = sc.nextInt();

        System.out.println("Enter the position to insert the element:");
        int pos = sc.nextInt();

        // Shift elements to the right from the given position
        for (i = n - 1; i >= pos - 1; i--) {
            arr[i + 1] = arr[i];
        }

        arr[pos - 1] = data;  // Insert the element
        n++;  // Increase array size

        System.out.println("--- Array after Insertion ---");
        for (i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}

Output:

Enter the number of elements (less than 20):
6
Enter the elements of the array:
1
2
3
4
5
6
Enter the element to insert:
10
Enter the position to insert the element:
5
// --- Array after Insertion ---
1 2 3 4 10 5 6

Explanation

Step	Description
arr[ ] = new int[20];	Declares an array with a maximum size of 20
n = sc.nextInt();	Reads the number of elements to store initially
arr[i] = sc.nextInt();	Stores user inputs into the array
for (i = n-1; i >= pos-1; i--)	Shifts elements to the right from the specified position
arr[pos-1] = data;	Inserts the new value at the desired position

Tips

Java arrays are not resizable, so we manually shift data to perform insertion.
Always check array bounds to avoid ArrayIndexOutOfBoundsException.
Prefer ArrayList if you need dynamic resizing.