1. Chapter 5

2.  We’ve been using UrRobot – knows only 5 things  Let’s now use a new type of Robot: Robot!  i.e. – public class MileMover extends Robot

3.  frontIsClear () – boolean, returns true or false   checks if immediate front has wall or not  nextToABeeper() – boolean   checks if corner it is on has a beeper  nextToARobot() – boolean  facingNorth() –  … south, east, west  anyBeepersInBeeperBag()  All methods are booleans!!!!  Still has all of UrRobot’s methods

4.  Karel can make decisions for himself!  Syntax:  if(condition)  { }  Example:  if(frontIsClear())  { move();}

5.  The parameter of the method (inside the brackets):  Any statement that will mean: if(true) or if(false)  Many ways to say true or false:  if(frontIsClear()) – if front is clear  If(! frontIsClear()) – if front is not clear   !  exclamation point means “not”

6.  Useful if you want only 1 of 2 alternatives  Ex) if(frontIsClear()) {{  move();  } //note – bracket is closed  Else {{  putBeeper(); }}

7.  Necessary when multiple conditions need to be tested  Ex) if(nextToABeeper())  { if(frontIsClear())  {pickBeeper();  move(); }} }}   good idea to only limit nested if statements to 2 – 3 nests

8.  What if:  If(facingWest())  { if(frontIsClear())  { if (nextToABeeper())  { if (nextToARobot())  }}}  We can fix this::  If(facingWest() && nextToABeeper() && nextToARobot())  Just use && (means AND)  Also - || means OR  These are called logical operators

9.  Test reversal  Bottom factoring  Top factoring  Redundant test factoring  All on pages 123-126  see how these work!

10.  All programs we have done have an issue where the robot might have an error shut off (ex – running into a wall)  Using our new methods, you should be able to reprogram the old programs to never have an error shut off   try it with MileMover - reprogram move, pickBeeper, and putBeeper so they won’t have error shutoffs   also – program Racer on page 123

11.  Start to include comments:  Each program should start with:  //your name  //AP Computer Science  // Chapter 5, pr #  // 10/##/09  Ch 5, #1, 2, 3, 6, 8, 9, 10, 11, 14  --large problem set, we will spend a lot of time in class on it, but make sure to program at home as well