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How to Insert an element at a specific position in an Array in Java

  • Difficulty Level : Medium
  • Last Updated : 02 Aug, 2021

An array is a collection of items stored at contiguous memory locations. In this article, we will see how to insert an element in an array in Java.
Given an array arr of size n, this article tells how to insert an element x in this array arr at a specific position pos.
 

Approach 1: 
Here’s how to do it.
 

  1. First get the element to be inserted, say x
  2. Then get the position at which this element is to be inserted, say pos
  3. Create a new array with the size one greater than the previous size
  4. Copy all the elements from previous array into the new array till the position pos
  5. Insert the element x at position pos
  6. Insert the rest of the elements from the previous array into the new array after the pos

Below is the implementation of the above approach:
 

Java




// Java Program to Insert an element
// at a specific position in an Array
 
import java.io.*;
import java.lang.*;
import java.util.*;
 
class GFG {
 
    // Function to insert x in arr at position pos
    public static int[] insertX(int n, int arr[],
                                int x, int pos)
    {
        int i;
 
        // create a new array of size n+1
        int newarr[] = new int[n + 1];
 
        // insert the elements from
        // the old array into the new array
        // insert all elements till pos
        // then insert x at pos
        // then insert rest of the elements
        for (i = 0; i < n + 1; i++) {
            if (i < pos - 1)
                newarr[i] = arr[i];
            else if (i == pos - 1)
                newarr[i] = x;
            else
                newarr[i] = arr[i - 1];
        }
        return newarr;
    }
 
    // Driver code
    public static void main(String[] args)
    {
 
        int n = 10;
        int i;
 
        // initial array of size 10
        int arr[]
            = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
 
        // print the original array
        System.out.println("Initial Array:\n"
                           + Arrays.toString(arr));
 
        // element to be inserted
        int x = 50;
 
        // position at which element
        // is to be inserted
        int pos = 5;
 
        // call the method to insert x
        // in arr at position pos
        arr = insertX(n, arr, x, pos);
 
        // print the updated array
        System.out.println("\nArray with " + x
                           + " inserted at position "
                           + pos + ":\n"
                           + Arrays.toString(arr));
    }
}
Output: 



Initial Array:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Array with 50 inserted at position 5:
[1, 2, 3, 4, 50, 5, 6, 7, 8, 9, 10]

 

Approach 2: 
Here’s how to do it.
 

  1. First get the element to be inserted, say element
  2. Then get the position at which this element is to be inserted, say position
  3. Convert array to ArrayList
  4. Add element at position using list.add(position, element)
  5. Convert ArrayList back to array and print

Below is the implementation of the above approach:
 

Java




// Java Program to Insert an element
// at a specific position in an Array
// using ArrayList
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
public class AddElementAtPositionInArray {
     
    // Method to add element at position
    private static void addElement(
        Integer[] arr, int element,
        int position)
    {
        // Converting array to ArrayList
        List<Integer> list = new ArrayList<>(
            Arrays.asList(arr));
         
        // Adding the element at position
        list.add(position - 1, element);
         
        // Converting the list back to array
        arr = list.toArray(arr);
 
        // Printing the original array
        System.out.println("Initial Array:\n"
                        + Arrays.toString(arr));
 
        // Printing the updated array
        System.out.println("\nArray with " + element
                        + " inserted at position "
                        + position + ":\n"
                        + Arrays.toString(arr));
    }
     
    // Drivers Method
    public static void main(String[] args)
    {
        // Sample array
        Integer[] arr = { 1, 2, 3, 4, 5,
                        6, 7, 8, 9, 10 };
     
        // Element to be inserted
        int element = 50;
     
        // Position to insert
        int position = 5;
     
        // Calling the function to insert
        addElement(arr, element, position);
    }
}
Output: 
Initial Array:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Array with 50 inserted at position 5:
[1, 2, 3, 4, 50, 5, 6, 7, 8, 9, 10]

 




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