Should I redefine or reassign a variable in a loop? [duplicate]

Question

Supposing I need to iterate over something and set a variable in every cycle, like this:

for (int i=0; i < list.size(); i++) {
    final Object cur = list.get(i);
}

this redefines the variable everytime, so I'm concerned that that might pollute the memory.

The alternate option is to define the variable once and then reassign it every iteration, like this:

Object cur
for (int i=0; i < list.size(); i++) {
    cur = list.get(i);
}

would this be better in terms of memory? Would it make any difference? What if cur is a primitive type instead of an Object?

Don't tell me to use foreach, I need the counter, this is just a simplified example

Answer 1

From a performance point of view, I would say if you need to improve this (you measured that a hot spot was here), you can choose the solution that offers best performances.

That said, I would recommend putting it inside the loop so that you cannot use it by error outside.

BTW, you'll ease debugging and readability by not having a variable that is there without knowing if it should or not be used outside the loop.