*** Official AP Computer Science A Thread 2013-2014 ***

Test Preparation AP Mathematics & Computer Science
221

<p>@jkhuggins Just wondering, how knowledgeable are you of Java outside of the AP subset? I know Java very well, but was hesitant about using parts of the language not covered by the subset.</p>

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<p>cool…can you tell us all the answers? lol</p>

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<p>@schakrab‌ I did use the grid’s get method to get the actors at the arraylist of locations, I just forgot that in my post :)</p>

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<p>@schakrab I’m positive I incremented moves on the test. The instructions said we could write whatever methods and variables we wanted so I made another method, haha. </p>

<p>On the actual test though turnActors was </p>

<p>ArrayList<location> locs = getOccupiedAdjacentLocations(getLocation());</location></p>

<p>for (loc:locs)
Actor acty = get(locs) //here I do realize I messed up, didn’t create a grid for myself to use the get method on. Should be gr.get(locs), whoops
acty.setDirection(acty.getDirection()+90);</p>

225

<p>@fievproko I think you’re fine; gr is a Grid<actor>, so the more specific declaration is actually more correct.</actor></p>

<p>@schakrab I’m a reader, not a writer :). Actually, one of my fellow readers is Maria Litvin, who with her husband Gary writes one of the major APCS textbooks. They’ve posted their annotated solutions: <a href=“http://www.skylit.com/beprepared/fr2014.html”>http://www.skylit.com/beprepared/fr2014.html&lt;/a&gt; </p>

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<p>@jkhuggins‌ Do you know when CollegeBoard will release the solutions and scoring guidelines? I am eager to see them…</p>

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<p>@MrVenKata they release the scoring guidelines when they release the test scores.</p>

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<p>@MoonMax‌ Thanks :)</p>

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<p>@jkhuggins‌ Oh good. Thank you so much.</p>

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<p>@MrVenKata Both will probably be released sometime over the summer. For the solutions: there are lots of “right” solutions already out there, like the Litvins I referenced above. The scoring guidelines aren’t finalized until the Reading (the event where we get together to score all the exams); we adjust the scoring guidelines after we see how students actually tried to solve the problem — this makes sure that we get a wide scoring range, rather than a lot of high scores or a lot of low scores.</p>

231

<p>For the trio I didn’t create instance variables for the food objects, just one for the name and one for the price. They didn’t specify anything other than the order of what the constructor inputs should be, and I take the three food objects and set the name and price to what they are right in the constructor. Then in the methods, I just return the variables. That’s okay because they don’t specify what the instance variables have to be right?</p>

232

<p>How many points do you think the will give me for part 1 of the 1st question if I declared a string, made a loop, tested for ArrayIndexOutOfBoundsException, and returned the string(Note: there are 2 parts to this question),</p>

233

<p>@schakrab That’s how I read it. You can store different things as your instance variables, as long as you produce the correct results at the end. (For what it’s worth, I did it your way :slight_smile: )</p>

234

<p>Is it okay if you use for loops instead of while loops?</p>

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<p>great minds think alike :)</p>

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<p>If anyone is interested, here is my response for the gridworld FRQ:</p>

<p>public class Director extends Rock
{
public Director()
{
setColor(Color.RED);
}</p>

<pre><code>public void act()
{
if(getColor().equals(Color.GREEN))
{
turnObjects();
setColor(Color.RED);
}

else if(getColor().equals(Color.RED))
{
    setColor(Color.GREEN);
}

}

public void turnObjects()
{

ArrayList&lt;Actor&gt; actors=getGrid().getNeighbors(getLocation());
for (Actor a:actors)
{
    a.setDirection(a.getDirection()+Location.RIGHT);
}

}
</code></pre>

<p>}</p>

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<p>@MrVenKata either for loops or while loops are fine; there’s no preference.</p>

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<p>Woohoo, all of my solutions match (or tested successfully in Eclipse) what was published @ <a href=“http://www.skylit.com/beprepared/fr2014.html”>http://www.skylit.com/beprepared/fr2014.html&lt;/a&gt;&lt;/p&gt;

<p>At most, I’ll lose 2 or 3 points for mistakes, but otherwise look golden. This was a really great test, minus the MC which was tedious for us all.</p>

239

<p>@jkhuggins Also, as a scorer, would you subtract a point for “List<string> list = new List<string>()”? I believe I forgot to do “List<string> list = new ArrayList<string>()”… Stupid mistake :|</string></string></string></string></p>

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<p>@terrapin45 It’s not that we subtract the point … it’s that you don’t earn the corresponding point in the rubric for correctly initializing the variable. But … yeah, that’s gonna get penalized.</p>