It is necessary to define local versions of distance because i need to define it via processing using the function serial.read. so you see, distance cant exist before set us because it needs to be assigned while the program is running
I think you are confusing yourself. You don't define distance from Processing. You assign distance a value that you get from Serial.read().
if so, how can i get around this problem.
There is no problem to get around, other than the one you have created in your mind.
Post your complete sketch, and we'll see if we can sort it out.