Except where otherwise noted, the contents of this document are
Copyright 2013 Stuart Reges and Marty Stepp.
lab document created by Marty Stepp, Stuart Reges and Whitaker Brand
Basic lab instructions
Mouse over highlighted words if you're not sure what they mean!
Talk to your classmates for
help.
You may want to bring your textbook to future labs
to look up syntax and examples.
Stuck? Confused? Have a question? Ask a TA for
help, or look at the book or past lecture slides.
Complete as much of the lab as you can within the allotted time. You don't need to keep working on these exercises after you leave.
Feel free to complete problems in any order.
Make sure you've signed in on the sign-in sheet before you leave!
Today's lab
Goals for today:
Practice problems in the same format as the final
Find resources to help tackle exam problems
Remember, the final is two hours. This lab is 50 minutes. Feel free to skip around!
You earn 1 point for each lab that you attend/show up on time for. Receiving credit for CSE 190 requires attending 8-10 labs. Please check that all your attendance records are correct on Canvas!
If you believe there is a problem with one of your scores, please email Price Ludwig at
pludwig@cs.washington.edu.
Exam Tips
Practice problems with pencil and paper. You will not be coding on a computer for the final. Many students find it extremely difficult to code on paper for the first time on exams.
Do not put "" around output.
If you're referring to the state of an array, use {}. If showing the printed output of an array, use the appropriate formatting (ex. if printed using Arrays.toString(), use [] around the array.)
Review the cheat sheet. It is non-identical to the midterm one.
No abbreviations/shorthand are allowed except S.o.p()/S.o.pln() for System.out.print() / System.out.println(), respectively.
More information on the Exams tab of the course website! (soon!)
Reference mysteries
Reference mysteries test your understanding of reference semantics and value semantics. Review the difference in lab 8, slide 12!
On the following slide, write the output resulting from the execution of each corresponding line of code:
Note: Remember that printing arrays using Arrays.toString() prints using [], not {}.
Exercise : reference mystery
public static void main(String[] args) {
int y = 1;
int x = 3;
int[] a = new int[4];
mystery(a, y, x); //2 3 [0, 0, 17, 0]^0-9,+
System.out.println(x + " " + y + " " + Arrays.toString(a)); //3 1 [0, 0, 17, 0]^0-9,+
x = y - 1;
mystery(a, y, x); //1 0 [17, 0, 17, 0]^0-9,+
System.out.println(x + " " + y + " " + Arrays.toString(a)); //0 1 [17, 0, 17, 0]^0-9,+
}
public static void mystery(int[] a, int x, int y) {
if (x < y) {
x++;
a[x] = 17;
} else {
a[y] = 17;
}
System.out.println(x + " " + y + " " + Arrays.toString(a));
}
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Exercise : Groceries
Write a method name groceries that accepts as its parameter a Scanner holding an input file. The data in the file represents grocery items purchased along with their price and their discount category. Your method should compute and return a real number representing the total cost of the grocery items.
Each item is represented by three tokens: (1) the name of the item (a single word), (2) its discount category ("red" (10% off full price), "blue" (25% off full price), or "none" (no discount)), and (3) its full price. The casing of the discount category is not guaranteed (for example, we could see "red", "RED", "rED", "rEd", or any other casing of the word "red").
Example input:
avocado RED 1 blueberries none 5 milk blue
2.00 cream red 1.00 cereal None 1.29
This should return 9.59.
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Exercise : Grasshopper
Write a class Grasshopper that extends the Critter class. A Grasshopper sits still until it gets into a fight. Once it fights, it celebrates its victory by doing a "hop".
A "hop" consists of moving NORTH a certain number of times, then SOUTH the same number of times, then WEST one time. The hops starts with a height of 1 (N, S, W), but each subsequent fight causes the next hop to be larger by one. The second hop is: (N, N, S, S, W). After finishing the hop, the Grasshopper sits idle again until it gets into another fight.
If a Grashopper is sitting still, it fights with Attack.ROAR. If a Grasshopper gets into a fight in the middle of a hop (while it is not sitting still), it always returns Attack.FORFEIT.
