Assertion problem

[sweety sinha]

class B {
private static int x1;
public void setX(int x) {x1 = x;}
public int getX() {return x1;}
public static void main(String[] args) {
int i1 = 0, j1 = 0;
do {
System.out.print(j1++);
assert (i1 = j1 + x1) < 6;
} while (i1 < 3);
}}

if setX method is never invoked then what would be the result?

Ans :
With assertions enabled it prints 012.
With assertions disabled it attempts to print an infinite sequence of numbers

Can anyone explain this???

[Nikos Pougounias]

Hi sinha,

with assertions disabled it's like the following line has comments

// assert (i1 = j1 + x1) < 6;    

If you take a look,

while (i1 < 3);

you'll see that the value of i1 controls the while loop. But with the above line commented, the value of i1 never changes; it's always 0!

[sweety sinha]

O.k i understand the second answer but i didn't get the 1st answer
why with assertion enabled it prints only 012 why not 012345???

thanks in advance

[Anand Shrivastava]

In your code since the set method is not being executed the value of x1 is default value that is 0.
the assert clause sets i1 to j1++ + x1
In the first iteration of the loop j1=0 and x1 is 0 (remember the post increment operator first uses the value in the expression and then increments it).
therefore i1 becomes 1 which is less than 6 so you assert true.
the while loop tests for i1<3 which is true.
So in the first iteration 0 is printed.

Similarly in the second iteration 1 is printed.
and in the third iteration 2 is printed.

But in the fourth iteration j1 becomes 3 and the while loop terminates as 3 is not less than 3.