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How to Extend an Array After Initialisation in Java?

Last Updated : 23 Jul, 2025
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In java, the arrays are immutable i.e. if the array is once assigned or instantiated the memory allocated for the array can't be decreased or increased. But there is one form of a solution in which we can extend the array. In this article, we will learn to increase the size of Array.

Extending an Array after Initialization

As we can't modify the array size after the declaration of the array, we can only extend it by initializing a new array and copying the values of the old array to the new array, and then we can assign new values to the array according to the size of the array declared.

Below are the examples to show extending the array after initialization.

Example 1:

Java 
// Java program to demonstrate
// extending an array
import java.lang.*;

class ExtendingArray {
  
    public static void main(String[] args)
    {

        String[] str = new String[] { "G", "E", "E" };

        // allocating space for 5 strings
        // in the extended array
        String[] ext = new String[5];
        ext[3] = "K";
        ext[4] = "S";

        // copying the array elements
        // to new extended array
        System.arraycopy(str, 0, ext, 0, str.length);

        for (String s : ext) {
            System.out.print(s);
        }
    }
}

Output
GEEKS


Example 2: 

Java 
// Java program to demonstrate
// extending an array

import java.lang.*;

class ExtendingArray {
  
    public static void extendedArray()
    {

        int[] arr = new int[] { 1, 2, 3, 4, 5, 6 };

        // allocating space for 10 integers
        int[] arr2 = new int[10];

        arr2[6] = 7;
        arr2[7] = 8;
        arr2[8] = 9;
        arr2[9] = 10;

        // copying old array to new array
        System.arraycopy(arr, 0, arr2, 0, arr.length);

        for (int str : arr2)
            System.out.print(str + " ");
    }

  	public static void main(String[] args)
    {

        ExtendingArray arr = new ExtendingArray();
      	arr.extendedArray();
    }
}

Output
1 2 3 4 5 6 7 8 9 10


 


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kadiummanisha
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