AP CS A Karel J Robot Review Sheet Chapters 5-6

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1 AP CS A Karel J Robot Review Sheet Chapters 5-6 Name: Date: Per: 1. List the 8 primitive predicates that can be used in an if clause: 2. In order for a new class (subclass) that you write to be able to use the 8 primitives above, the class must have been derived from the class at some point in the inheritance chain. 3. When is each of the following iteration structures used? (true/false The choice of which loop construct to use (which tool) is an arbitrary decision left up to you and your preference.) a) while b) for 4. List the 4 steps for building a while loop. Also, in section 6.6, what are the 2 things we should ALWAYS check when writing any loop to help verify its correctness. 5. Write the correct form for the selection and iteration control structures. You should use generic statements such as <test> and <instructions>. a) for b) while c) if

2 6. simplify if (frontisclear()) 7. simplify if (nexttoabeeper()) turnright(); 8. simplify if (!nexttoarobot()) return false; return true;

3 9. Complete the following class, adding any additional methods you might need to help you (note: you should at this point be able to recognize which methods need further modularization and which can be written only in terms of primitives - please modularize where appropriate). public class JumpHarvestAndTest extends Robot //precondition: robot is facing east and standing next to the base of an arbitrarily high hurdle //postcondition: robot is facing east and is standing on the other side of the hurdle at the base public void jump() //precondition: there are an arbitrary number of piles of beepers in a line terminated with a wall segment each pile has an arbitrary number of beepers x, such that 0 x<infinity //postcondition: robot has picked up all beepers from the position it started at up to and including the intersection next to the wall public void harvestalltowall() //precondition: robot has an arbitrary number of beepers in bag //postcondition: returns true if rear is clear and the robot has exactly 2 beepers in its bag; false otherwise //note: you may NOT use && nor for this exercise public boolean rearisclearandrobothas2beepersinbag() Friendly reminder: In order to help ensure the reading of the chapter, we usually put a question or 2 from the reading (which we didn t cover in class) on the test. :-)

4 public class BigEagleBot extends LittleEagleBot public BigEagleBot(int st, int ave, Direction mydir, int num) super(st, ave, mydir, num); public void twist() swing(); super.scramble(2); public void scramble(int numswings) for(int i = 0; i < numswings; i++) super.scramble(i); public class LittleEagleBot extends SmartRobot public LittleEagleBot(int st, int ave, Direction mydir, int num) super(st, ave, mydir, num); public void swing() scramble(3); public void scramble(int nummoves) for(int i = 0; i < nummoves; i++) For each Robot defined below, how many times does the robot move() For each Robot defined below, how many times does the robot turnleft() 1 LittleEagleBot k1 = new LittleEagleBot (3, 3, North, 0); k1.swing(); 2 LittleEagleBot k2 = new LittleEagleBot (4, 2, North, 0); k2.scramble(5); 3 BigEagleBot k3 = new BigEagleBot (5, 3, East, 0); k3.twist(); 4 BigEagleBot k4 = new BigEagleBot (5, 7, North, 0); k4.scramble(4);

5 Questions 5 20 involve reasoning about the following classes. Assume BetterTurner extends Robot and implements goforward() and stopatobstacle(). Assume SmartRobot extends BetterTurner and implements faceeast() and goforth(). public class MathRobot extends SmartRobot public MathRobot(int st,int ave, Direction mydir,int num) super(st, ave, mydir, num); public void linear() /* implementation not shown */ public void quadratic() /* implementation not shown */ public void complex() /* implementation not shown */ public class CompSciRobot extends MathRobot public CompSciRobot(int st,int ave, Direction mydir,int num) super(st, ave, mydir, num); public void watson() /* implementation not shown */ public void bigblue() /* implementation not shown */ public void hal() /* implementatiaon not shown */ Assume that turnerbot is a ABetterTurner, einsteinbot is a SmartRobot, nerdbot is a MathRobot and geekbot is a CompSciRobot. Identify the following as either valid calls or invalid. 5 turnerbot.move() 6 turnerbot.stopatobstacle() 7 turnerbot.faceeast() 8 einsteinbot.goforth() 9 einsteinbot.goforward() 10 einsteinbot.turnleft() 11 nerdbot.complex() 12 nerdbot.stopatobstacle() 13 nerdbot.hal() 14 nerdbot.linear() 15 nerdbot.goforth() 16 CompSciRobot.bigBlue() 17 geekbot.turnright() 18 geekbot.quadratic() 19 geekbot.watson() 20 geekbot.move()

6 For the following questions consider the following class declaration and world: public class PracticeRobot extends SmartRobot public PracticeRobot (int st,int ave, Direction mydir, int num) super(st, ave, mydir, num); public boolean moveforwardandnexttoarobot() return nexttoarobot(); public boolean moveleftandnexttoabeeper() return nexttoabeeper(); For each of the following code fragments, (note consider each fragment separately from the other fragments) determine the final location && direction of each robot. PracticeRobot alpha = new PracticeRobot(3, 1, North, 5); 21 if (aplha.moveforwardandnexttoarobot()) alpha. alpha.turnright(); // Assume turnright() exist PracticeRobot beta = new PracticeRobot(3, 3, North, 5); 22 if (beta.moveleftandnexttoabeeper()!beta.moveforwardandnexttoarobot() ) beta. beta.turnright() // Assume turnright() exist PracticeRobot gamma = new PracticeRobot(3, 6, North, 5); 23 if (!gamma.frontisclear() &&!gamma.moveleftandnexttoabeeper() gamma. gamma.turnright() // Assume turnright() exist PracticeRobot delta = new PracticeRobot(3, 7, North, 5); 24 if (delta.nexttoabeeper() && delta.moveforwardandnexttoarobot() ) delta. delta.turnright() // Assume turnright() exist