Java – create variables in advance to use (?) in the loop

Which of the two is more "effective":

for (int i = 0; i < 10; i++) {
    int x = i * 2;
}

Or –

int x;
for (int i = 0; i < 10; i++) {
    x = i * 2;
}

(just an example)

I know they are essentially different - so please don't solve their differences

What if both prove to do the same thing - creating an X variable multiple times is a less efficient method, rather than just creating it once and simply reassigning its value?

Solution

No, in this case, there is no performance difference using the compiler

From a readability point of view, I prefer the first method, but this is something to be discussed elsewhere

However, as part of the reward for this answer:

for (int x = 0; x < calculateUserCountFromDatabaSEOrSomething(); x++) {
   //Do stuff
}

In the above example, this will be a performance problem, because the calculateUserCountFromDatabaSEOrSomething () method will be invoked in each iteration of the loop. This must be considered when writing software