Why does the Java Collections Framework offer two different ways to sort?

Question

If I have a list of elements I would like to sort, Java offers two ways to go about this.

For example, lets say I have a list of Movie objects and I’d like to sort

Answer 1

I'm not sure I find it that odd. I have a list of things to sort that have a natural order like numbers. Do I really expect I have to tell the API how to compare numbers? I wouldn't look for a two-arg method, intuitively. Thus Comparable exists.

But of course you can and should be able to define a different ordering, thus the other method. For example, even though numbers have a natural ordering, I may still want a different ordering: for example, order by value descending. Thus Comparator exists.

And of course some things don't have a natural ordering like Fruit, but you might still wish to order a list of them. Thus Comparator, again.