I think the original author is vanished. I hope he has not dropped the Java class yet. Only suggestions I have to you is: READ THE BOOK AND LISTEN CLASS LECTURES CAREFULLY before you go out there, seeking for help. 

First, recognize what you need to know to solve the excercise you're given.  You already got the solution; however, if you look at your exercise carefully, you know that it needs some lessons on basic Java class syntax, different types of LOOP in Java, and use of math function library. Very simple! Not a rocket science. So, open your book and read it.

If you don't know fundamentals of programming language, then read the book again from the beginning. Know how a program is created, complied, and executed. Try to take advantage of debugger that comes with the editor you use. Don’t give up just because you get some discouraging comments from some people.  Call it a quit only when your heart tells you to quit.