Java Program to Concatenate Two Arrays - The Coding Shala

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 In this post, we will learn how to concatenate two arrays using a Java program.

Java Program to Concatenate Two Arrays

Write a Java program to concatenate two given arrays and print the new array.

Example 1:

Input: arr1 = [1, 2, 3]

            are2 = [4, 5]

Output: [1, 2, 3, 4, 5]

Solution 1

We can create a new array and the size of this array will be the size of array1 + the size of array2, and copy all the elements from array1 and array2 to this new array.

Java Program: 

/**
 * https://www.thecodingshala.com/
 */

public class Main {

    public static void arrayConcat(int[] arr1, int[] arr2) {
        int len1 = arr1.length;
        int len2 = arr2.length;
        int[] res = new int[len1 + len2];

        int index = 0;
        // add first array
        for (int i=0; i<len1; i++) {
            res[index] = arr1[i];
            index++;
        }

        // add second array
        for (int i=0; i<len2; i++) {
            res[index] = arr2[i];
            index++;
        }

        // print array
        for (int i=0; i<res.length; i++) {
            System.out.print(res[i] + " ");
        }
    }

    public static void main(String[] args) {
        // concat integer arrays
        int[] arr1 = {1, 2, 3, 4, 5};
        int[] arr2 = {6, 7, 8, 9, 10};
        System.out.println("First array is: ");
        for (int i=0; i<arr1.length; i++) {
            System.out.print(arr1[i] + " ");
        }

        System.out.println();
        System.out.println("Second array is: ");
        for (int i=0; i<arr2.length; i++) {
            System.out.print(arr2[i] + " ");
        }

        System.out.println();
        System.out.println("Array after concatenate: ");
        arrayConcat(arr1, arr2);
    }
}

Output: 

First array is: 
1 2 3 4 5 
Second array is: 
6 7 8 9 10 
Array after concatenate: 
1 2 3 4 5 6 7 8 9 10 

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