Swap Two Adjacent Elements in an Array: This Java program takes an input array containing integers and swaps adjacent elements to create a modified array. It achieves this by iterating through the array with a step size of 2 (i.e., taking every second element) and swapping the positions of each pair of adjacent elements.
Swap Two Adjacent Elements in an Array
package com.softwaretestingo.interviewprograms;
public class InterviewPrograms33 
{
	/*
	 * Input array- {1,2,3,4,5} 
	 * Output array- {2,1,4,3,5}
	 */
	public static void main(String[] args) 
	{
		int[] arr = {1,2,3,4,5};
		int tmp=0;
		for(int i =1;i<arr.length;i+=2)
		{
			tmp=arr[i];
			arr[i]=arr[i-1];
			arr[i-1]=tmp;
		}
		for(int i:arr)
			System.out.print(i);
	}
}
Output
21435
Alternative Way 1:
This Java program takes an input array containing integers and swaps adjacent elements to create a modified array. The program achieves this using a for loop and conditional statements to handle arrays of even and odd lengths.
package com.softwaretestingo.interviewprograms;
import java.util.Arrays;
public class InterviewPrograms33_1 
{
	/*
	 * Input array- {1,2,3,4,5} 
	 * Output array- {2,1,4,3,5}
	 */
	public static void main(String[] args) 
	{
		int [] a = {1,2,3,4,5};
		if ( a.length % 2 == 1 )
		{ 
			for ( int i = 0 ; i<a.length-1; i=i+2) 
			{
				int temp= a[i];
				a[i]= a[i+1];
				a[i+1]=temp;
			}
		}
		else if (a.length%2==0) 
		{
			for (int i=0; i<a.length; i=i+2)
			{
				int temp= a[i];
				a[i] = a[i+1];
				a[i+1]= temp ;
			}
		}
		System.out.println(Arrays.toString(a));
	}
}
Output
[2, 1, 4, 3, 5]