I read this code in this book:
SCJP Sun Certified Programmer
for Java® Platform, SE6
Study Guide
I can't understand how Reverse method work, so How these numbers are sorted?
What Reverse method? There isn't a Reverse() method anywhere. You are creating a Reverse object. What can you not see about its workings? You have got the whole class there in front of you Go through it with a pencil and paper and see how it works.