The point of this assignment is not to have you copy pseudocode out of the book. In fact, just about everyone will get full or nearly full credit for this assignment (assuming you hand it in, of course). The point is for you to learn to write a correct clipping algorithm.
So, leave your notes and text closed; bring a few sheets of paper and something to write with; craft your algorithm from scratch; implement it; and see if it works!
See the Assignment 1 handout for details about the courseware. As usual, problems should be reported to fusion@graphics.lcs.mit.edu.
Again, Java details can be found in the The Java Language Specification.
Clipping lines is fun, and makes them safer.