Thread: first itteration of "for" statement acts differntly to all the rest, why?

Dear All I have the following code and it works, just trying to understand the results.

public class Counter
{
public static void main(String[] args)
{
int value1 = 7;
for (int i = 2, sum = 0; i <= value1; i += i, sum = i)
{
System.out.println("Sum = " + sum + "  i = " + i );
}}}

OUTPUT OF CODE:
Sum = 0 i = 2
Sum = 4 i = 4

QUESTION
So why, on the first go around of the "for" statement, is "sum" not equal to 2?

MY ANSWER TO QUESTION
If the third part of the "for" statement(; i += i, sum = i) is being ignored in the first iteration of the loop, the results I see make sense?

FURTHER EVIDENCE FOR MY ANSWER
This also makes sense, because the first part of the "for" statement is being ignored after the first iteration of the "for" loop, otherwise "sum" and "i" would be set back to there original values.

SECOND QUESTION:
Am I correct in my assumptions?

SPACE MONKEY

What is value1 supposed to be? Better yet, post an SSCCE that we can copy and paste to play with.

Dear KevinWorkman:

Sorry "value1" has been set, it is there to set the upper limit for "i", to indicate when the "for" statement should stop running.

I made it so I could set "value1" to different values. I have turned "value1" into a fixed value as it is not integral to the question I have posed.

Originally Posted by SPACE MONKEY

So why, on the first go around of the "for" statement, is "sum" not equal to 2.

The answer to that question is because "the third part" (the increment expression) of the loop executes after each iteration of the loop, not before.

Recommended reading: The for Statement (The Java™ Tutorials > Learning the Java Language > Language Basics)

I'd also recommend you step through this with a debugger. That will make it pretty obvious what's going on.