Hi,
In your program line:
you've got one too few "=" in your R3 comparison, so it is actually an assignment. This is a fairly common newbie error. One nice thing about
Java is that it will catch this kind of error at compile time. In a language like C or C++, the assignment R3 = 0 will be treated logically as false no matter what value R3 had going into the expression. (It looks like you may have some other syntax errors in your code as well, but one at a time!)
By the way, one of the things the FAQ may mention is that
you should surround your program excerpts in code brackets (you can use the button at the top of the message editor). That will display your code with formatting for easier reading.