Java Integer Addition Within a For Loop -

i wrote following code accept integer user through console input. code supposed add positive integers 1 number chosen user yield sum. example, if user enters 5, output should 15 (1+2+3+4+5). reason, code wrote ends outputting square of whatever value user inputs. is, user input of 4 results in 16, etc. wrong. if have insights might me fix this, appreciate it. many thanks!

import java.util.scanner;  public class onedashsix{     public static void main(string[] args){         //create new scanner object         scanner input=new scanner(system.in);         //receive user input          system.out.print("enter integer find arithmetic sum: ");         int mynumber=input.nextint();         int sum = 0;         //calculate sum of arithmetic series         for(int i=1; i<=mynumber; i=i++)         {             sum=sum+mynumber;         }         //display results console         system.out.println("the sum of first " +          mynumber + " positive integers " + sum + ".");     } } 

this line

sum=sum+mynumber; 

needs be

sum=sum+i; 

edit: it's worth...the fastest way discard loop:

sum = (mynumber * (mynumber + 1)) / 2;