Jtips #29

[Yuki Cho]

Can you please tell me why the value of j is 7?
Thanks, Yuki

class Q29 {
public static void main(String[] args) {
int j = 0;
Q29 test = new Q29();
try {
for (j=1 ; j < 5 ; j++)
{
j+= j;
}
int i = test.process() / (j = 5);
}
catch (Exception e) {
System.out.println(e);
System.out.println("Value of j = " + j);
}
}

int process() throws Exception {
throw new Exception("Exception Encountered");
}
}
Answer: Prints java.lang.Exception: Exception Encountered and Value of j=7.

[Stevie Kaligis]

Hi...,
let examine the "for looping" :
1. syntax is :
for (expression1, expression2, expression3)
{
...//loop body
}
2. expression3 will be evaluated if and only if the the expression2 is "true", and the loop body is complete normally (i.e - didn't use "break" to stop the looping)
let see your code :
for (j=1 ; j < 5 ; j++)
{
j+= j;
}
1. when j = 1, expression2 is "true", the loop body will be evaluated j = 1 + 1, j = 2,
2. and then evaluated expression3 (j++), j now is 3,
3. when j = 3, expression2 is "true", the loop body will be evaluated j = 3 + 3, j = 6,
4. and then evaluated expression3 (j++), j now is 7,
5. when j = 7, expression2 is "false", the loop body will not be evaluated (last value of j = 7)
now let see second code :
1. if LHO is "complete abruptly", the RHO will not be evaluated
int i = test.process() / (j = 5);
}
since LHO (test.process) complete abruptly, RHO (j = 5) will not be evaluated, so j is still 7.

hope thats help
stevie

[Yuki Cho]

That really helps. Thanks Stevie!!!
-Yuki