<p>I'm taking the AP Computer Science A exam, but since the class is mostly self-study, I'm really not getting any work done in that class. Are there any helpful study guides, outlines, or sample tests? Just reading the BPJ textbook and looking at past exams isn't helping, as my mock test scores are reflecting.</p>
<p>And any tips for the actual exam?
Thanks!</p>
<p>You can try this test if you haven’t yet:</p>
<p><a href=“http://coffman.dublin.k12.oh.us/teachers/teacherpages/king/apcs/CompSciAPracticeExam.pdf[/url]”>http://coffman.dublin.k12.oh.us/teachers/teacherpages/king/apcs/CompSciAPracticeExam.pdf</a></p>
<p>Do you know which areas you don’t know well / make mistakes in?</p>
<p>I just reminded my friends taking it Tuesday of a few things (I took it last year):</p>
<ul>
<li>Integer division truncates (5 / 4 = 1 while 5.0 / 4 = 1.25)</li>
<li>Strings use .length() for length</li>
<li>ArrayLists use .size() for length</li>
<li>Arrays use .length for length</li>
<li><p>Always check to make sure loops don’t go out of bounds (esp. in free response)</p></li>
<li><p>substring(x) returns the string from index x to the tend</p></li>
<li><p>substring(x, y) returns the string from x up to (not including) y</p></li>
<li><p>.charAt(x) returns the char at index x</p></li>
<li><p>When simplifying boolean expressions, the idea of distributing a ! can help:
!(a && b) is the same as !a || !b (note that &&'s and ||'s switch)</p></li>
<li><p>Easy way to find what recursive methods return:
public int recur(int n) {</p></li>
</ul>
<p>if(n < 2) return 3;</p>
<p>return recur(n - 1) + 2 * n;</p>
<p>}</p>
<p>What does recur (4) return?</p>
<p>Think mathematically and recur as a function:</p>
<p>r(4) = r(3) + 8</p>
<p>Find r(3) = r(2) + 6</p>
<p>find r(2) = r(1) + 4;</p>
<p>find r(1) = 3</p>
<p>Now you can plug things back in and solve</p>
<p>r(2) = 7
r(3) = 13
r(4) = 21</p>
<p>^Wow thank you for that help.</p>
<p>That recursion technique helped me a ton. Thanks!</p>
<p>What does polymorphism mean? and overiding? I can’t understand the barrons book’s definition</p>
<p>Polymorphism is basically when a method does different things based on what it’s acting on.
Overriding is when you have a method in a parent class, and an identical method tag in the child class. The method in the child class is said to override the method in the parent class. </p>
<p>Does anyone know a good way/resource to learn GridWorld? I learned all the programming quite well (got through the AB material, and then realized there’s no AB test anymore… haha), but I never really bothered to lean Grid World – seriously regretting that now.</p>
<p>@OtherWindow
Thanks! That was really helpful, especially the explanation of the recursive method tip. I’ve always had problems with recursive methods, GridWorld, and following/writing loops.</p>
<p>@SuperCuber
GridWorld is a quarter of the test D:
I’d recommend downloading the GridWorld case study and working through it. Even though I struggle with GridWorld problems, actually watching the bugs move through the grid has helped me to picture a lot of what their questions are asking. And then just look through GridWorld sample FRQs, I guess. But I can’t help much beyond that, since GridWorld is killing me on the mocks…</p>
<p>Yeah I know… 
Thanks though - I’ll be working through the case study - woohoo!</p>
<p>gah I need a released exam pm please if you have either 2004 or 2009 we can talk there</p>
<p>barrons book is very helpful…esp the practice multiple choice and its on google books if you dont want to go out and buy it…just work through the multiple choice
all of the MC on the exam are trying to trick you so if you can recognize the tricks…the mc section can be easy
remember on the free response to at least attempt it, because partial credit is super easy to receive!</p>
<p>@OtherWindow
THANK YOU. I actually had questions in my head for my teacher about size()/length/length(), and about substring…questions that I probably would’ve forgotten. So once again, thanks!</p>
<p>hey, can anyone give me some tips on gridworld frq’s</p>
<p>Bump, can anyone give tips for APCS FRQs?</p>
<p>1) It’s a bit late at this point, but … practice using some of the past year’s FRQs.</p>
<p>2) Make sure and read the question carefully. The FRQs aren’t intentionally tricky … but you don’t want to spend your time trying to do something the question doesn’t ask you to do.</p>