Question

I have a quick question in regards to the value of how variable values work. I am working on a program right now, which looks like this:

public void run() {

    println("There are " + ATOMS + " initially.");

    int atoms = ATOMS;
    int year = 0;

    while (atoms > 0) {

        for (int i = atoms; i > 0; i--) {

            println(i);
            if( rgen.nextBoolean() ) {
                atoms--;
                println("The total atoms is " + atoms);
            }

            println("The total for i is " + i + "\n"  );

        }

         year++;

         println("There are " + atoms + " at the end of year " + year );
    }

}

At the part with the for loop, and setting the variable i to the value of atoms, is what has me confused. Lets say the value of atoms starts at 20. It goes through the for loop and lets assume that the first time through the RandomGenerator makes it true. So that subtracts 1 from atoms. Then after that the value of i should also be minused due to the i–. So my question is: When I set the variable i to the value of atoms does that just take i and set it to the initial value of 20? And then from there every time I adjust the value of i it is taking off of its own version of 20, and then when I change the value of atoms it, too has its own value. So when I subtract from atoms, that is not also being subtracted from i? That is the only way I can make sense of it because this program is written and works correctly, but that part has me confused.

Thank you very much in advance for any help!

Answer 1

yes you have answered your own question. the variable i and atoms are two separate instances.

when you start the loop you are setting i equal to the same value as atoms but they are still separate variables. therefore inside the loop when you change the value of one it does not affect the other.