Marine Biology Simulation Case Study

Object Diagrams

This file contains links to a number of diagrams that illustrate object interactions in the Java-based Advanced Placement^® Computer Science Marine Biology Simulation case study.

In these object diagrams, each object of a class is represented by a rectangle containing the name of the object's class, an icon representing the object, and a list of its methods. The diagrams also use arrows between method names to indicate object interactions, and include an outline summary of the algorithmic behavior being illustrated.

Most diagrams show only the public methods for the objects, although a few include the protected methods for objects of the Fish class. It is easy to distinguish between public and protected methods: public methods, which represent an object's interface to other objects, project beyond the edge of the rectangle representing the object. Protected methods, on the other hand, are encapsulated inside the object rectangle.

The following object diagrams are available:

• Cast of Characters, a visual list of the key classes and objects in the case study.  (pdf version)
• The Driver, which shows the responsibilities of the program driver (which might be an applet, a main method, a graphical user interface, etc.).  The program driver constructs the key objects in the simulation and then runs the simulation by repeatedly calling the Simulation object's step method. (pdf version)
• Running the simulation (original program described in Chapters 1 and 2):
  • The Simulation step method, representing the behavior of each timestep in the simulation. (pdf version)
  • The Fish act and move methods, illustrating the behavior of a single fish in a single timestep.  (To see these methods separately, see act only and move only.)   (pdf versions of act and move, act only, and move only)
    • Determining the fish's next location (nextLocation method) (pdf version)
    • Locating the empty neighboring locations around the fish (emptyNeighbors method) (pdf version)
• Fish Modifications to add breeding and dying (Chapter 3):
  • modified Fish act method (pdf version)
    • move method (unchanged) (pdf version)
    • breed method (new) (pdf version)
    • die method (new) (pdf version)
• Specialized Fish (Chapter 4):
  • Fish Class Hierarchy - DarterFish and SlowFish show methods inherited from Fish as well as methods they define themselves (pdf version)
  • DarterFish, showing inherited and redefined/overridden methods (pdf version)
  • DarterFish: the redefined move and nextLocation methods (pdf version)
  • SlowFish, showing inherited and redefined/overridden methods (pdf version)
  • SlowFish: the redefined nextLocation method (pdf version)
• Environment Implementations (Chapter 5):
  • Environment Class Hierarchy - BoundedEnv and UnboundedEnv show only the methods defined in those classes (pdf version)
  • Environment Class Hierarchy - BoundedEnv and UnboundedEnv show methods inherited from SquareEnvironment as well as methods they define themselves (pdf version)
• Blank Diagrams for Your Own Object-Oriented Designs:
  • Blank Object Diagrams - a page containing blank object diagrams (pdf version)
  • Blank CRC Cards - a page containing blank CRC cards (pdf version)

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