import java.util.Scanner;

public class Lab09{

public static void main(String[] args) {

int num;

Scanner in = new Scanner(System.in);

System.out.print(" Enter a number : ");

num = in.nextInt();

for(int i = 1;i <= num;i++){

if(i % 2 != 0)

System.out.print(2*i+" ");

else

System.out.print(-(2*i-1)+" ");

}

System.out.println();

}

}

Once version 1 is working correctly, add method to class and call it isEven(num) that gets an int number and returns true if the number is even, and false otherwise. Call this method inside your loop (which is inside the main method) and replace it with whatever you had for checking whether or not count is even or odd.