Question

I can not understand how to use the same function in several java classes. For example, I have the following function:

public int plus(int one, int two) {
  return one + two;
}

How can I use that in several other files (classes)?
Should I create that in separate class?

Answer 1

If the implementation is always going to be the same (one+two), you could instead turn it into a static method, like this:

class Util{
    public static int plus(int one, int two) {
        return one + two;
    }
}

Then you can call the function like

int result = Util.plus(1,1)