Java Array Clone

Many times, we need to clone an array to backup the original elements of it. We have some special strings and numbers like palindrome number, palindrome string, and Armstrong number, and to check their specialty, we need to clone the array. For example, to check whether a string is a palindrome or not, we first convert a string into a character array and clone the char array as a temp. Now, we reverse the elements of the char array and compare it with the temp that contains the original string.

In simple words, we need to clone the array when we want to back up the original data. In Java, we have four ways to clone an array which are as follows:

By Copying Array Elements

It is the naive way to clone an array. In this method, we iterate the original array and put each element of the array into another array. We clone the array by copying elements in the following way:

CloneArrayExample1.java

// import required classes and packages if any
import java.util.Scanner;
// create class CloneArrayExample1 to clone an array
public class CloneArrayExample1 {
	// main() method start
	public static void main(String[] args)
	{
		// declare originalArray and cloneArray variables
		 int originalArray[];
		 int cloneArray[];
		 int size;
		 // create Scanner class object to take input from user
		 Scanner sc = new Scanner(System.in);
		 System.out.println("Enter the size of the array.");
		 size = sc.nextInt();
		 // initialize both the array with the given size
		 originalArray = new int[size];
		 cloneArray = new int[size];
		 System.out.println("Enter elements of the original array:");
		 //take input from user to fill originalArray
		 for(int i = 0; i < size; i++) {
			 originalArray[i] = sc.nextInt();
		 }
		 
		 // close scanner class object
		 sc.close();
	     // use for loop to copy elements from originalArray to cloneArray
	     for (int i = 0; i < originalArray.length; i++) {
	    	 cloneArray[i] = originalArray[i];
	     }	
	     // display elements of the original array
	     System.out.println("Elements of the original array:");
	
	     for (int i = 0; i < originalArray.length; i++) {
	         System.out.print(originalArray[i] + " ");
	     }
	
	     // display elements of the cloned array
	     System.out.println("\n\nElements of the clone array:");
	
	     for (int i = 0; i < cloneArray.length; i++) {
	         System.out.print(cloneArray[i] + " ");
	     }
	}
}

Output:

Using clone() Method

In the above method, we have iterated the original array to make a clone of it. We have another way that takes less time to clone the given array, i.e., the clone() method of the Object class. The syntax of the clone() method is as follwos:

Let's implement the code to clone an array by using Object's clone() method:

CloneArrayExample2.java

//import required classes and packages if any
import java.util.Scanner;
//create class CloneArrayExample2 to clone an array using clone() method
public class CloneArrayExample2 {
	// main() method start
	public static void main(String[] args)
	{
		// declare originalArray and cloneArray variables
		 int originalArray[];
		 int cloneArray[];
		 int size;
		 // create Scanner class object to take input from user
		 Scanner sc = new Scanner(System.in);
		 System.out.println("Enter the size of the array.");
		 size = sc.nextInt();
		 
		 // initialize both the array with the given size
		 originalArray = new int[size];
		 cloneArray = new int[size];
		 System.out.println("Enter elements of the original array:");
		 //take input from user to fill originalArray
		 for(int i = 0; i < size; i++) {
			 originalArray[i] = sc.nextInt();
		 }
		 // close scanner class object
		 sc.close();
	     // use clone() method of Object class to clone originalArray
	     cloneArray = originalArray.clone();
	
	     // display elements of the original array
	     System.out.println("Elements of the original array:");
	     for (int i = 0; i < originalArray.length; i++) {
	         System.out.print(originalArray[i] + " ");
	     }	
	     // display elements of the cloned array
	     System.out.println("\n\nElements of the clone array:");
	     for (int i = 0; i < cloneArray.length; i++) {
	         System.out.print(cloneArray[i] + " ");
	     }
	}
}

Output:

Using arraycopy() Method

Just like the clone() method, we can also use the arraycopy() method of the System class available in the java.lang package. The arraycopy() method has the following syntax:

public static void arraycopy(Object src, int srcPos, Object dest, int destPos, int length)

Here, src defines the source array, srcPos defines the index from where copying should be started, dest defines the array in which elements will be copied, destPos defines the index from which the copied elements are placed in the clone array, and length is the size of the subarray to be copied.

Let's implement the code to clone an array by using the System.arraycopy() method:

CloneArrayExample3.java

//import required classes and packages if any
import java.util.Scanner;
//create class CloneArrayExample3 to clone an array using System.arraycopy() method
public class CloneArrayExample3 {
	// main() method start
	public static void main(String[] args)
	{
		// declare originalArray and cloneArray variables
		 int originalArray[];
		 int cloneArray[];
		 int size;
		 // create Scanner class object to take input from user
		 Scanner sc = new Scanner(System.in);
		 System.out.println("Enter the size of the array.");
		 size = sc.nextInt();
		 // initialize both the array with the given size
		 originalArray = new int[size];
		 cloneArray = new int[size];
		 System.out.println("Enter elements of the original array:");
		 //take input from user to fill originalArray
		 for(int i = 0; i < size; i++) {
			 originalArray[i] = sc.nextInt();
		 }
		 // close scanner class object
		 sc.close();
	     // use System.arrayCopy() method to clone originalArray
	     System.arraycopy(originalArray, 0, cloneArray, 0, size);
	     // display elements of the original array
	     System.out.println("Elements of the original array:");
	     for (int i = 0; i < originalArray.length; i++) {
	         System.out.print(originalArray[i] + " ");
	     }
	     // display elements of the clone array
	     System.out.println("\n\nElements of the clone array:");
	     for (int i = 0; i < cloneArray.length; i++) {
	         System.out.print(cloneArray[i] + " ");
	     }
	}
}

Output:

Using copyOf() Method

Just like clone() and arraycopy() methods, we can also use copyOf() method of the Arrays class available in the java.util package. The copyOf () method has the following syntax:

Here, arr defines the original array, and len is the length of the array to get copied.

Let's implement the code to clone an array by using arraycopy() method of Arrays class:

CloneArrayExample4.java

//import required classes and packages if any
import java.util.Scanner;
import java.util.Arrays;
//create class CloneArrayExample4 to clone an array using arraycopy() method of Arrays class
public class CloneArrayExample4 {
	// main() method start
	public static void main(String[] args)
	{
		// declare originalArray and cloneArray variables
		 int originalArray[];
		 int cloneArray[];
		 int size;
		 // create Scanner class object to take input from user
		 Scanner sc = new Scanner(System.in);
		 System.out.println("Enter the size of the array.");
		 size = sc.nextInt();
		 // initialize both the array with the given size
		 originalArray = new int[size];
		 cloneArray = new int[size];
		 System.out.println("Enter elements of the original array:");
		 //take input from user to fill originalArray
		 for(int i = 0; i < size; i++) {
			 originalArray[i] = sc.nextInt();
		 }
		 
		 // close scanner class object
		 sc.close();
		 
	     // use copyOf() method to clone originalArray
	     cloneArray = Arrays.copyOf(originalArray, size);
	
	     // display elements of the original array
	     System.out.println("Elements of the original array:");
	
	     for (int i = 0; i < originalArray.length; i++) {
	         System.out.print(originalArray[i] + " ");
	     }
	
	     // display elements of the clone array
	     System.out.println("\n\nElements of the clone array:");
	
	     for (int i = 0; i < cloneArray.length; i++) {
	         System.out.print(cloneArray[i] + " ");
	     }
	}
}

Output:

Using copyOfRange() Method

Lust like copyOf() method, Arrays class provide copyOfRange() method to clone an array. The copyOfRange() method is used to copy the elements of the specified range of the original array into clone array. The syntax of the copyOfRange() method is as follows:

Here, the original defines the original array, from defines initial index and to defines the final index of the element.

Let's implement the code to clone an array by using arraycopyRange() method of Arrays class:

CloneArrayExample5.java

//import required classes and packages if any
package javaTpoint.JavaExample;
import java.util.Scanner;
import java.util.Arrays;
//create class CloneArrayExample5 to clone an array using copyOfRange() method of Arrays class
public class CloneArrayExample5 {
	// main() method start
	public static void main(String[] args)
	{
		// declare originalArray and cloneArray variables
		 int originalArray[];
		 int cloneArray[];
		 int size;
		 // create Scanner class object to take input from user
		 Scanner sc = new Scanner(System.in);
		 System.out.println("Enter the size of the array.");
		 size = sc.nextInt();
		 // initialize both the array with the given size
		 originalArray = new int[size];
		 cloneArray = new int[size];
		 System.out.println("Enter elements of the original array:");
		 //take input from user to fill originalArray
		 for(int i = 0; i < size; i++) {
			 originalArray[i] = sc.nextInt();
		 }
		 // close scanner class object
		 sc.close();
	     // use copyOfRange() method to clone originalArray
	     cloneArray = Arrays.copyOfRange(originalArray, 0, size);
	     // display elements of the original array
	     System.out.println("Elements of the original array:");
	     for (int i = 0; i < originalArray.length; i++) {
	         System.out.print(originalArray[i] + " ");
	     }
	     // display elements of the clone array
	     System.out.println("\n\nElements of the clone array:");
	
	     for (int i = 0; i < cloneArray.length; i++) {
	         System.out.print(cloneArray[i] + " ");
	     }
	}
}

Output: