Question

I have a simple function called a lot.

Inside this function, I have many calls to the size of a list (containing around 10 elements):

list.size()

Is it faster for me to use a temporary variable to get the size only once, or is it faster to call the size() method every time?

Update: it’s an ArrayList.

Note: I know what I am doing, I am not looking for a lecture regarding optimization and how it should or shouldn’t be done. I am just looking for an answer.

Answer 1

It depends on implementation of the List
Looking at the ArrayList‘s source

/**
  225        * Returns the number of elements in this list.
  226        *
  227        * @return the number of elements in this list
  228        */
  229       public int size() {
  230           return size;
  231       }
  232   

So it doesn’t matter if you take a local variable or call this method