GridWorld
Case Study for AP Exam
Provides experiments to observe the attributes and
behavior of the actors
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Interface
Interface is a group of related methods with
empty bodies. Grid is an interface.
All methods defined by that interface must
appear in its source code before the class will
successfully compile.
ActorWorld
Must create an ActorWorld for objects to be
added to Grid.
Created in the runner class. (main method)
ActorWorld world = new ActorWorld();
Inheritance
Inheritance is way to define a new class using
classes which have already been created
The word extends allows the class to inherit all
the field data and methods from the class it is
extending
public class Bug extends Actor {
• The parent class is termed super class also known as base class and
the inherited class is the sub class also known as child.
• The keyword extends is used by the subclass to inherit the features
of super class
• The subclass inherits all of the field data and all of the methods
defined in the superclass.
Bug
Constructors:
public Bug()
{
setColor(Color.RED);
}
Bug b = new Bug();
Will create a red bug that is facing
North
/**
* Constructs a bug of a given color.
* @param bugColor the color for this bug
*/
public Bug(Color bugColor)
Bug b =
{
Choose
setColor(bugColor);
}
new Bug(Color.BLUE);
Color; facing North
Color.BLACK, Color.DARK_GRAY, Color.GRAY, Color.LIGHT_GRAY, Color.WHITE,
Color.MAGENTA, Color.RED, Color.PINK, Color.ORANGE, Color.YELLOW,
Color.GREEN, Color.CYAN, Color.BLUE
Color is in the java.awt Class
import java.awt.Color;
Methods in Bug
public boolean canMove()
{
Grid<Actor> gr = getGrid();
// gets all actors in the grid
if (gr == null)
return false;
Location loc = getLocation(); // returns location
Location next = loc.getAdjacentLocation(getDirection()); // space ahead
if (!gr.isValid(next)) // if space ahead is not empty or valid space
Actor neighbor = gr.get(next); // get the actor at space ahead
return (neighbor == null) || (neighbor instanceof Flower); // return t or f
// True: ok to move into empty location or onto flower
// False: not ok to move onto any other actor
}
Bug
public void move()
{
Grid<Actor> gr = getGrid(); // get all actors in grid
if (gr == null) // if no actors in grid
return;
Location loc = getLocation(); //get location
Location next = loc.getAdjacentLocation(getDirection());
if (gr.isValid(next)) // if location next is valid True
moveTo(next);
// move to next location
else
removeSelfFromGrid(); // if not remove from grid
Flower flower = new Flower(getColor()); //create flower
flower.putSelfInGrid(gr, loc); //put flower in loc
}
Bug
* Turns the bug 45 degrees to the right without
changing its location.
*/
public void turn()
{
setDirection(getDirection() + Location.HALF_RIGHT);
}
//gets current direction and adds 45
What other angles can he turn?
Bug
/**
* Moves if it can move, turns otherwise.
*/
public void act()
{
if (canMove())
move();
else
turn();
}
Inherited from Actor
BugRunner2
• Open BugRunner and change name to
BugRunner2.
• Create a Bug and make his color be one of the
color words
• Create a Location
Location loc2 = new Location(4,7);
Bug b2 = new Bug(Color.MAGENTA);
world.add(loc2,b2);
Bug
• Never change Bug
• You create different types of Bugs by
extending Bug.
• BoxBug extends Bug
To Do
• Finish observation of Bug from yesterday and
complete the questions. (Should be done
quickly)
• Change BugRunner to BugRunner2 and make
additions as indicated on the sheet.
• Start reading and looking at the BoxBug program.
Complete questions from observation.
BoxBug extends Bug
• BoxBug - BoxBug is a child of Bug.
• A BoxBug moves like a bug but it traces out a square with a certain
side length.
• The act method is overridden. (Changed) This is polymorphism.
• When a subclass overrides a method from the parent class using
the same method name it is called polymorphism. The compiler
chooses the method to execute at run time.
• if a BoxBug is blocked, it makes two right turns and starts again. A
BoxBug has property called sideLength. If a BoxBug has a
sideLength of k, then you will see k+1 flowers on each side of its
traced out diagram.
Assignment Read pages 10-12
Answer questions 1-7
Create programs 1-3 page 13,14
Gridworld – Part 2 (BoxBug)
1. Read (and re-read and re-re-read) Part 2 pages 10 - 12.
2. BoxBug and BoxBugRunner are in the boxBug folder under
GridWorldCode\projects.
3. Work with your "table" partner(s) and answer the
questions in Set 2 on page 12 (#1 - 7). Everyone should
fill out their own sheet.
4. Work with a partner to complete Exercises 1 – 3 CircleBug,
SpiralBug, and ZBug. You should create a new "runner"
program for each bug.
5. You may work together, but each person needs to type up
the code and get it to run.