hi friend,

Try the following code may this will be helpful for you

package net.roseindia;

import java.util.Scanner;

public class SumOfSeries {

    public static void sum(int n)
    {
        int total = 0;
        for(int i=1; i<=n; i++)
        {
            if(i<n)
            {
            System.out.print(i+"+");
            }           
            total = total+i;    
        }
        System.out.println(n+" = "+total);              
    }
    public static void main(String args[])
    {
        Scanner scan = new Scanner(System.in);
        System.out.print("Enter the last number : ");
        int num = scan.nextInt();
        sum(num);
    }
}

o/p is displaying 1+2+3+4+5=15

But i need o/p as 1+2-3+4-5=-1