Java Program to Copy an Array

Write a Java Program to Copy an Array without using Built-in function, and using copyof method with example.

Java Program to Copy an Array using CopyOf Method

In this program we are using the Array.copyOf method to copy one array to another.

// Java Program to Copy an Array
import java.util.Scanner;
import java.util.Arrays;

public class CopyArray1 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Size, i;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		for (i = 0; i < Size; i++)
		{
			a[i] = sc.nextInt();
		}   
		
		int[] b = Arrays.copyOf(a, Size);
		
		System.out.println("\n **** Elements in b[] Array after Copying are **** ");
		for (i = 0; i < Size; i++)
		{
			System.out.println(" Element at b["+ i +"] = " + b[i]);
		}
	}
}

OUTPUT

Java Program to Copy an Array using For Loop

This program allows the user to enter the size, and the One Dimensional Array elements. Next, it will copy each and every element in a[] array to b[] array using For Loop.

// Java Program to Copy an Array
import java.util.Scanner;

public class CopyArray2 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Size, i;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		int [] b = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		for (i = 0; i < Size; i++)
		{
			a[i] = sc.nextInt();
		}   
		
		for (i = 0; i < Size; i++)
		{
			b[i] = a[i];
		} 
		
		System.out.println("\n **** Elements in b[] Array after Copying are **** ");
		for (i = 0; i < Size; i++)
		{
			System.out.println(" Element at b["+ i +"] = " + b[i]);
		}
	}
}

OUTPUT:

ANALYSIS

First, We declared 2 One dimensional arrays of user specified size. And they are a, b of integer type.

Below For Loop will iterate each and every cell present in the a[] array. Condition inside the for loops (i < Size)) will ensure the compiler, not to exceed the array size. Statement inside the for loop will store the user entered values as array element such as a[0], a[1], a[2], a[3], a[4]

for (i = 0; i < Size; i++)
{
	a[i] = sc.nextInt();
}

In the next line, We have one more for loop to iterate each and every element, and save it in b[] array

for (i = 0; i < Size; i++)
{
	b[i] = a[i];
}

In this Java Program to Copy an Array example, User inserted values are a[5] = {19, 25, 18, 79, 125}}

First Iteration: for (i = 0; 0 < 5; 0++)
The value of i will be 0 and the condition (i < 5) is True. So, it will start executing the statements inside the loop until the condition fails.

b[i] = a[i]
b[0] = a[0]
b[0] = 19

Second Iteration: for (i = 1; 1 < 5; 1++)
The value of i will be 1 and the condition (i < 5) is True.

b[1] = a[1]
b[1] = 25

Third Iteration: for (i = 2; 2 < 5; 2++)

b[2] = a[2]
b[2] = 18

Do the same for remaining iterations until the condition (i < 5) fails.

Next for loop is to print the elements in b[] array. I suggest you to refer Java Program to Print Array Elements article to understand the same

Java Program to Copy an Array using While Loop

This Java copy array example is same as above but this time we used While Loop to copy elements from one array to another array.

// Java Program to Copy an Array
import java.util.Scanner;

public class CopyArray3 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Size, i = 0, j = 0, k = 0;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		int [] b = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		while(i < Size)
		{
			a[i] = sc.nextInt();
			i++;
		}   
		
		while(j < Size)
		{
			b[j] = a[j];
			j++;
		} 
		
		System.out.println("\n **** Elements in b[] Array after Copying are **** ");
		while(k < Size)
		{
			System.out.println(" Element at b["+ k +"] = " + b[k]);
			k++;
		}
	}
}

OUTPUT