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GridWorld

GridWorld. Analyzing the subclasses of Actor. Actor class (all AP testable!). Definition: An actor is an entity with a color and direction that can act. The actor is the GridWorld super class. Behavior: ????. Fields: Grid<Actor> grid Location location int direction Color color.

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GridWorld

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  1. GridWorld Analyzing the subclasses of Actor

  2. Actor class (all AP testable!) Definition: An actor is an entity with a color and direction that can act. The actor is the GridWorld super class. Behavior: ???? Fields: Grid<Actor> grid Location location int direction Color color

  3. Questions about an Actor’s behavior • What does an Actor know about itself? • What does an Actor do when acts? • What class does Actor extend? What interface does it implement? • How does an Actor relate to objects of other classes such as Grid objects? • What are the pre-conditions on the methods of an Actor and what do these mean for its behavior? • What are the post-conditions on the methods of an Actor and what do these mean for its behavior?

  4. Constructor /** * Constructs a blue actor that is facing north. */ public Actor() { color = Color.BLUE; direction = Location.NORTH; grid = null; location = null; }

  5. Accessors /** * Gets the color of this actor. * @return the color of this actor */ public Color getColor() { return color; } /** * Gets the current direction of this actor. * @return the direction of this actor, an angle between 0 and 359 degrees */ public int getDirection() { return direction; } /** * Gets the grid in which this actor is located. * @return the grid of this actor, or <code>null</code> if this actor is * not contained in a grid */ public Grid<Actor> getGrid() { return grid; } /** * Gets the location of this actor. * @return the location of this actor, or <code>null</code> if this actor is * not contained in a grid */ public Location getLocation() { return location; }

  6. Mutators /** * Sets the color of this actor. * @param newColor the new color */ public void setColor(Color newColor) { color = newColor; } /** * Sets the current direction of this actor. * @param newDirection the new direction. The direction of this actor is set * to the angle between 0 and 359 degrees that is equivalent to * <code>newDirection</code>. */ public void setDirection(int newDirection) { direction = newDirection % Location.FULL_CIRCLE; if (direction < 0) direction += Location.FULL_CIRCLE; }

  7. Mutators dealing with Grid /** * Puts this actor into a grid. If there is another actor at the given * location, it is removed. <br /> * Precondition: (1) This actor is not contained in a grid (2) * <code>loc</code> is valid in <code>gr</code> * @paramgr the grid into which this actor should be placed * @param loc the location into which the actor should be placed */ public void putSelfInGrid(Grid<Actor> gr, Location loc) { if (grid != null) throw new IllegalStateException( "This actor is already contained in a grid."); Actor actor = gr.get(loc); if (actor != null) actor.removeSelfFromGrid(); gr.put(loc, this); grid = gr; location = loc; } /** * Removes this actor from its grid. <br /> * Precondition: This actor is contained in a grid */ public void removeSelfFromGrid() { if (grid == null) throw new IllegalStateException( "This actor is not contained in a grid."); if (grid.get(location) != this) throw new IllegalStateException( "The grid contains a different actor at location " + location + "."); grid.remove(location); grid = null; location = null; }

  8. Mutators dealing with moving /** * Moves this actor to a new location. If there is another actor at the * given location, it is removed. <br /> * Precondition: (1) This actor is contained in a grid (2) * <code>newLocation</code> is valid in the grid of this actor * @paramnewLocation the new location */ public void moveTo(LocationnewLocation) { if (grid == null) throw new IllegalStateException("This actor is not in a grid."); if (grid.get(location) != this) throw new IllegalStateException( "The grid contains a different actor at location " + location + "."); if (!grid.isValid(newLocation)) throw new IllegalArgumentException("Location " + newLocation + " is not valid."); if (newLocation.equals(location)) return; grid.remove(location); Actor other = grid.get(newLocation); if (other != null) other.removeSelfFromGrid(); location = newLocation; grid.put(location, this); } /** * Reverses the direction of this actor. Override this method in subclasses * of <code>Actor</code> to define types of actors with different behavior * */ public void act() { setDirection(getDirection() + Location.HALF_CIRCLE); }

  9. Other methods /** * Creates a string that describes this actor. * @return a string with the location, direction, and color of this actor */ public String toString() { return getClass().getName() + "[location=" + location + ",direction=" + direction + ",color=" + color + "]"; }

  10. Questions about an Actor’s behavior • What does an Actor know about itself? • What does an Actor do when acts? • What class does Actor extend? What interface does it implement? • How does an Actor relate to objects of other classes such as Grid objects? • What are the pre-conditions on the methods of an Actor and what do these mean for its behavior? • What are the post-conditions on the methods of an Actor and what do these mean for its behavior?

  11. Questions about an Bug’s behavior • What does a Bug know about itself? • What does a Bug do when acts? • What class does Bug extend? What interface does it implement? • How does a Bug relate to objects of other classes? • What are the pre-conditions on the methods of a Bug and what do these mean for its behavior? • What are the post-conditions on the methods of a Bug and what do these mean for its behavior? • How does the Bug’s behavior differ from its super class Actor?

  12. Bug class (all AP testable!) Definition: A Bug is an actor that can move and turn. It drops flowers as it moves. Behavior: ???? Fields:inherited from Actor: Grid<Actor> grid Location location int direction Color coloradditional fields: None

  13. Constructors /** * Constructs a red bug. */ public Bug() { setColor(Color.RED); } /** * Constructs a bug of a given color. * @param bugColor the color for this bug */ public Bug(Color bugColor){ setColor(bugColor); }

  14. Constructors /** * Constructs a red bug. */ public Bug() { super(); //Java puts this in by default setColor(Color.RED); } /** * Constructs a bug of a given color. * @param bugColor the color for this bug */ public Bug(Color bugColor){ super(); //Java puts this in by default setColor(bugColor); }

  15. ASIDE: Rules about super in constructors

  16. Accessors Inherited from Actor: public Color getColor() public int getDirection() Grid<Actor> getGrid() public Location getLocation() Inherited from Actor: public Color setColor() public void setDirection() public void putSelfInGrid(Grid<Actor> gr, Location loc) public void removeSelfFromGrid() public void moveTo(Location newLocation) public void act() Additional methods: public void act() public void turn() public void move() Mutators Other public boolean canMove()

  17. Additional Methods /** * Moves if it can move, turns otherwise. */ public void act() { if (canMove()) move(); else turn(); } /** * Turns the bug 45 degrees to the right without changing its location. */ public void turn() { setDirection(getDirection() + Location.HALF_RIGHT); }

  18. Additional Methods /** * Moves the bug forward, putting a flower into the location it previously * occupied. */ public void move() { Grid<Actor> gr = getGrid(); if (gr == null) return; Location loc = getLocation(); Location next = loc.getAdjacentLocation(getDirection()); if (gr.isValid(next)) moveTo(next); else removeSelfFromGrid(); Flower flower = new Flower(getColor()); flower.putSelfInGrid(gr, loc); } /** * Tests whether this bug can move forward into a location that is empty or * contains a flower. * @return true if this bug can move. */ public boolean canMove() { Grid<Actor> gr = getGrid(); if (gr == null) return false; Location loc = getLocation(); Location next = loc.getAdjacentLocation(getDirection()); if (!gr.isValid(next)) return false; Actor neighbor = gr.get(next); return (neighbor == null) || (neighbor instanceof Flower); // ok to move into empty location or onto flower // not ok to move onto any other actor }

  19. Questions about an Bug’s behavior • What does a Bug know about itself? • What does a Bug do when acts? • What class does Bug extend? What interface does it implement? • How does a Bug relate to objects of other classes? • What are the pre-conditions on the methods of a Bug and what do these mean for its behavior? • What are the post-conditions on the methods of a Bug and what do these mean for its behavior? • How does the Bug’s behavior differ from its super class Actor?

  20. BoxBug • Ask questions about behavior and show code

  21. CircleBug, SpiralBug, • Ask questions about behavior and show code needed to back up your answers.

  22. Flower, Rock • Ask questions about behavior and show code needed to back up your answers.

  23. Zbug, Dancing Bug • Ask questions about behavior and show code needed to back up your answers.

  24. Your Bug??? • Ask questions about behavior and show code needed to back up your answers.

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