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How to add an element to an Array in Java?
  • Last Updated : 30 Sep, 2019

Given an array of size n, the task is to add an element x in this array in Java.

The size of the array cannot be changed dynamically in Java, as it is done in C/C++. Hence in order to add an element in the array, one of the following methods can be done:

  1. By creating a new array:
    • Create a new array of size n+1, where n is the size of the original array.
    • Add the n elements of the original array in this array.
    • Add the new element in the n+1 th position.
    • Print the new array.

    Below is the implementation of the above approach:




    // Java Program to add an element in an Array
      
    import java.io.*;
    import java.lang.*;
    import java.util.*;
      
    class GFG {
      
        // Function to add x in arr
        public static int[] addX(int n, int arr[], int x)
        {
            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 n
            // then insert x at n+1
            for (i = 0; i < n; i++)
                newarr[i] = arr[i];
      
            newarr[n] = x;
      
            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 added
            int x = 50;
      
            // call the method to add x in arr
            arr = addX(n, arr, x);
      
            // print the updated array
            System.out.println("\nArray with " + x
                               + " added:\n"
                               + Arrays.toString(arr));
        }
    }
    Output:
    Initial Array:
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    
    Array with 50 added:
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 50]
    
  2. By using ArrayList as intermediate storage:
    • Create an ArrayList with the original array, using asList() method.
    • Simply add the required element in the list using add() method
    • Convert the list to an array using toArray() method




    // Java Program to add an element in an Array
      
    import java.io.*;
    import java.lang.*;
    import java.util.*;
      
    class GFG {
      
        // Function to add x in arr
        public static Integer[] addX(int n, Integer arr[], int x)
        {
            int i;
      
            // create a new ArrayList
            List<Integer> arrlist
                = new ArrayList<Integer>(
                    Arrays.asList(arr));
      
            // Add the new element
            arrlist.add(x);
      
            // Convert the Arraylist to array
            arr = arrlist.toArray(arr);
      
            // return the array
            return arr;
        }
      
        // Driver code
        public static void main(String[] args)
        {
      
            int n = 10;
            int i;
      
            // initial array of size 10
            Integer 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 added
            int x = 50;
      
            // call the method to add x in arr
            arr = addX(n, arr, x);
      
            // print the updated array
            System.out.println("\nArray with " + x
                               + " added:\n"
                               + Arrays.toString(arr));
        }
    }
    Output:
    Initial Array:
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    
    Array with 50 added:
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 50]
    

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