Java Program to Copy an Array in Reverse

Java Program to Copy an Array in Reverse

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In the previous article, we have seen Java Program to Copy an Array to Another Array

In this article we are going to see how we can copy an array in reverse.

Java Program to Copy an Array in Reverse

Array is a data structure which stores a fixed size sequential collection of values of single type. Where with every array elements/values memory location is associated. Each array elements have it’s own index where array index starts from 0.

In Array set of variables referenced by a single variable name and it’s array index position. It is also called as a container object which contains elements of similar type.

Declaration of an array:

dataType[] arrayName; (or)                              //Declaring an array
dataType []arrayName; (or)
dataType arr[];

Instantiation of an Array:

arrayName = new datatype[size];                    //Allocating memory to array

Combining both Statements in One:

dataType[] arrayName = new dataType[size] //Declaring and Instantiating array

Initialization of an Array:

arrayName[index-0]= arrayElement1             //Initializing the array

...

arrayName[index-s]= arrayElementS

Combining all Statements in One:

dataType arrayName[ ]={e1,e2,e3};               //declaration, instantiation and initialization

Let’s see different ways to copy an array in reverse.

Method-1: Java Program to Copy an Array in Reverse By Static Initialization of Array Elements

Approach:

  • Create and initialize an array.
  • Display the array to the user.
  • Copy each element from the last location to the first location and store it in our copied array.
  • Display the copied array.

Program:

import java.util.Arrays;
import java.util.Collections;
public class Main
{
    public static void main(String args[])
    {
        //Original array
        int arr[] = {12, 22, 34, 22, 54};
        int copyarr[] = new int[arr.length];
        // Printing the array
        System.out.println("The array elements are : "+Arrays.toString(arr));
        // Copying each element from the array
        for(int i = 0;i<arr.length;i++)
            copyarr[i] = arr[arr.length-i-1];
        System.out.println("The copied array elements are : "+Arrays.toString(copyarr));
    }
}


Output:

The array elements are : [12, 22, 34, 22, 54]
The copied array elements are : [54, 22, 34, 22, 12]

Method-2: Java Program to Copy an Array in Reverse By Dynamic Initialization of Array Elements

Approach:

  • Create and initialize an array.
  • Display the array to the user.
  • Copy each element from the last location to the first location and store it in our copied array.
  • Display the copied array.

Program:

import java.util.*;

public class Main
{
    public static void main(String args[])
    {
        Scanner scan = new Scanner(System.in);
        
        // Taking size as input from the user
        System.out.println("Enter the array size :");
        int size = scan.nextInt();
        
        // Creating the array
        int arr[] = new int[size];
        
        // Entering the array elements
        System.out.println("Enter array elements : ");
        for(int i=0;i<size;i++)
        {
            arr[i] = scan.nextInt();
        }
        
        int copyarr[] = new int[arr.length];
        // Printing the array
        System.out.println("The array elements are : "+Arrays.toString(arr));
        // Copying each element from the array
        for(int i = 0;i<arr.length;i++)
            copyarr[i] = arr[arr.length-i-1];
        System.out.println("The copied array elements are : "+Arrays.toString(copyarr));
    }
}


Output:

Enter the array size :
6
Enter array elements : 
1 2 3 4 5 6
The array elements are : [1, 2, 3, 4, 5, 6]
The copied array elements are : [6, 5, 4, 3, 2, 1]

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