for loop question

[donald rieck]

where exactly does the var i increment in this code:
public class Myfor {
public static void main(String argv[]) {
int i;
int j;

outer: for ( i=1 ; i<3 ; i++ )

inner: for ( j=1 ; j<3 ; j++ ) {
if (j==2) continue outer;
System.out.println( i + " " + j );
}
}
}
the output is : 1 1
2 1
But I just figure it out!
where is i & j incrementing? why a 2 and a 1?
help please!!!

[Michael Morris]

Hi Donald:
outer: for ( i=1 ; i<3 ; i++ )
i is incremented with the the ++ postfix operator at the end of every iteration of the for loop. Let's analyze it:

    outer: for ( i=1 ; i<3 ; i++ )
        inner: for ( j=1 ; j<3 ; j++ ) {
            if (j==2) continue outer;
            System.out.println( i + " " + j );
        }

When the outer loop begins, i = 1. Then the inner loop begins and j = 1. Next the if condition is tested and evaluates false so the System.out prints the values of i and j or 1 1. Now j is incremented to be 2. The next iteration of inner begins and the if now evaluates true which causes the outer loop to complete its iteration, incrementing i in to process to now be 2. The inner loop now starts all over, j is 1 again and the same exact thing happens except that now i is 2, so the System.out prints 2 1. On the next iterarion of inner j becomes 2 and the if is true again causing outer to finish the current iteration and incrementing i to 3 but alas the conditional of the outer loop is i < 3 so the outer loop finishes and we are thru.
Michael Morris

[Junilu Lacar]

for loop execution is as follows:
1. initialization expression executes
2. loop condition is evaluated: if true,
body of the for statement is executed,
otherwise the for statement is complete
3. increment expression is evaluated, repeat step 2
continue causes a "short circuit" of the body execution and typically goes straight to step 3 above. If a label is involved, then the short circuiting goes all the way back to the for statement after the label.
In your example:
1. i is initialized to 1
2. (i < 3) is true
3. j is initialized to 1
4. (j < 3) is true
5. if (j == 2) is false
6. output: "1 1"
7. j++ evaluated; j is now 2
8. if (j == 2) is true
9. continue outer; short-circuits normal loop execution
10. i is incremented; i is now 2
11. outer loop condition evaluated: (i < 3) ==> 2 < 3 ==> is true
12. j is initialized to 1
13. if (j == 2) is false
14. output: "2 1"
15. j++ evaluated; j is now 2
16. if (j == 2) is true
17. continue outer; short-circuits normal loop execution; inner for loop terminates
18. i is incremented; i is now 3
19. outer loop condition evaluated: (i < 3) ==> (3 < 3) ==> false; outer loop terminates