ballWorlds.framework
Class BallManagerWorld

java.lang.Object
  ballWorlds.framework.BallManagerWorld

All Implemented Interfaces:

BallManager

Direct Known Subclasses:

VisibleWorld

public class BallManagerWorld
extends Object
implements BallManager

An BallManagerWorld provides a thread-safe implementation of BallManager, subject to the CAUTION below. It maintains the List of all Balls in its World.

The methods in this class that modify or iterate through this BallManager's List of Balls are synchronized. This prevents the ConcurrentModificationException that might arise if one Thread (e.g. the GUI Thread) adds or removes a Ball from the List of Balls while another Thread (e.g. the Thread that asks each Ball to "act") is iterating through the List of Balls.

CAUTION: Two methods return the List of Balls maintained by this BallManager:

• The allBallsInWorld method returns a shallow copy of that List. Methods that call allBallsInWorld can safely use the shallow copy without fear of the ConcurrentModificationException that would arise if one Thread (e.g. the GUI Thread) adds or removes a Ball from the List of Balls while the Thread of the method that called allBallsInWorld method is iterating through that same List of Balls returned by this method.if The protected method getBallsInWorld returns this BallManager's internal List of Balls, for clients that cannot afford the time to make a copy

  Author:

  David Mutchler, Salman Azhar, Curt Clifton and others, January 2005. Modified September 2008, September 2009.

  Constructor Summary

  BallManagerWorld()
  Initializes the list of Balls to an empty list.

  Method Summary

  void	addBall(Ball ballToAdd) Adds the given Ball to this World.
  List<Ball>	allBallsInWorld() Returns a List that contains all the Balls in this World.
  protected List<Ball>	getBallsInWorld() Returns the actual List of Balls in this World.
  Ball	intersectingBall(Ball ballToCheckForIntersections) Returns a Ball that intersects the given Ball, or null if no Ball intersects the given Ball.
  List<Ball>	intersectingBalls(Ball ballToCheckForIntersections) Returns a List that contains all the Balls in this World that intersect the given Ball
  Ball	nearestBall(Point2D p) Returns the Ball in this World that is nearest the given point.
  void	removeBall(Ball ballToRemove) Removes the given Ball from this World.

  Methods inherited from class java.lang.Object

  clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  Constructor Detail

  BallManagerWorld

  public BallManagerWorld()

  Initializes the list of Balls to an empty list. Mutates its given universe to include this World.

  Parameters:

  universe - All the Worlds in the Universe

  Method Detail

  addBall

  public void addBall(Ball ballToAdd)

  Description copied from interface: BallManager

  Adds the given Ball to this World.

  Specified by:

  addBall in interface BallManager

  Parameters:

  ballToAdd - the Ball to add to this World.

  removeBall

  public void removeBall(Ball ballToRemove)

  Description copied from interface: BallManager

  Removes the given Ball from this World.

  Specified by:

  removeBall in interface BallManager

  Parameters:

  ballToRemove - the Ball to remove from this World.

  nearestBall

  public Ball nearestBall(Point2D p)

  Description copied from interface: BallManager

  Returns the Ball in this World that is nearest the given point. Returns null if there are no Balls at all in this World.

  Specified by:

  nearestBall in interface BallManager

  Parameters:

  p - the point for which to find the nearest Ball.

  Returns:

  the Ball in this World that is nearest the given point.

  intersectingBall

  public Ball intersectingBall(Ball ballToCheckForIntersections)

  Description copied from interface: BallManager

  Returns a Ball that intersects the given Ball, or null if no Ball intersects the given Ball.

  Specified by:

  intersectingBall in interface BallManager

  Parameters:

  ballToCheckForIntersections - Ball to check for intersection with other Balls.

  Returns:

  a Ball that intersects this Ball, or null if no Ball intersects this Ball.

  intersectingBalls

  public List<Ball> intersectingBalls(Ball ballToCheckForIntersections)

  Description copied from interface: BallManager

  Returns a List that contains all the Balls in this World that intersect the given Ball

  Each call to this method returns a fresh List object that contains all the Ball objects in this World that intersect the given Ball independently from any other List objects in use at the same time. This allows the caller to safely iterate through this List without fear of it being concurrently modified by other Threads (and possibly generating a ConcurrentModification exception).

  Specified by:

  intersectingBalls in interface BallManager

  Parameters:

  ballToCheckForIntersections - Ball to check for intersection with other Balls.

  Returns:

  a List that contains all the Balls in this World that intersect the given Ball.

  allBallsInWorld

  public List<Ball> allBallsInWorld()

  Description copied from interface: BallManager

  Returns a List that contains all the Balls in this World.

  Each call to this method returns a fresh List object that contains all the Ball objects in this World independently from any other List objects in use at the same time. This allows the caller to safely iterate through this List without fear of it being concurrently modified by other Threads (and possibly generating a ConcurrentModification exception).

  Specified by:

  allBallsInWorld in interface BallManager

  Returns:

  a List that contains all of the Balls in this World.

  getBallsInWorld

  protected final List<Ball> getBallsInWorld()

  Returns the actual List of Balls in this World.

  CAUTION: Methods that call this method must be synchronized with this method (and the other methods of this class). Otherwise, the method that calls this method might experience the ConcurrentModificationException that would arise if one Thread (e.g. the GUI Thread) adds or removes a Ball from the List of Balls while the Thread of the method calling this method is iterating through that same List of Balls returned by this method.

  Returns:

  the actual List of Balls in this World.