Video question @ 3:15.

Sandy;

Take a look at the Comparable docs that Craig was viewing. What that is basically saying is that if we do x.compareTo(y) we get returned to us one of three values, -1, 0, or 1, depending on the comparison, right?

For example...

class Main {
  public static void main(String[] args) {
    Integer x = 3;
    Integer y = 5;

    System.out.println(x.compareTo(y));
  }
}

Since x is less than y, we get a -1 as a result. The inverse portion that is discussed in the video and in the documentation is that we need to assume and expect that if our output of x.compareTo(y) results in -1 that if we do y.compareTo(x) we will get a 1. That make sense, right? In the example code x is less than y so we get a -1. Using the same numbers then, y is greater than x must return a 1.

It is part of the contract we enter into when we implement Comparable we guarantee that we are going to provided the required information in a proper format, and Java guarantees it isn't going to act odd and say "Yea, 3 is less than 5, but 5 is also less than 3" when we do the compareTo() method check.

Does that help clear anything up? Post back if you still have questions or my ramblings don't make sense.

Happy coding,
Ken

Ken, thanks for your help. Your explanation helped solidify my understanding of the comparable interface doc. The only hang up I had was the term inverse mainly for future references when dealing with numbers that aren't whole.