Is there a difference in performance for calling .length on an array versus saving a size variable?

Question

I am creating a simulation program, and I want the code to be very optimized. Right now I have an array that gets cycled through a lot and in the various for loops I use

 for(int i = 0; i<array.length; i++){
       //do stuff with the array
 }

I was wondering if it would be faster if I saved a variable in the class to specify this array length, and used that instead. Or if it matters at all.

Answer 1

Accessing the length attribute on an array is as fast as it gets.

You'll see people recommending that you save a data structure size before entering the loop because it means a method all for each and every iteration.

But this is the kind of micro-optimization that seldom matters. Don't worry much about this kind of thing until you have data that tells you it's the reason for a performance issue.

You should be spending more time thinking about the algorithms you're embedding in that loop, possible parallelism, etc. That'll be far more meaningful in your quest for an optimized solution.