Marine Biology Simulation Part II: Assignment, Milestone 1

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Marine Biology SimulationPart II Assignment,
Milestone 1

• Dung Zung Nguyen
• Mathias Ricken
• Stephen Wong

TeachJava 2004! June 25, 2004
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Rice MBS Assignment

• Target Audience
• Students at the end of an objects-first CS2
• Length of Assignment
• Two milestones
• Approximately 10 hours of work
• Probably supported by one or two labs

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Studying the Case Study
White-box Framework Extension by Subclassing
Unit tests guide the way
Variant Fish Behavior
Variant Environment Behavior
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Studying the Case Study
Static Behavior!
Separate the variants from the invariants
Strategy Pattern
Dynamic Behavior Change
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Rice MBS Assignment

• Milestone 1
• Part 1 KnightFish
• Add a new fish species to the simulation
• Part 2 WrappingEnv
• Add a new kind of environment
• Milestone 2
• Part 3 Internals
• Re-implement parts of the simulation framework
• Part 4 Behavior Strategies
• Refactor framework to allow dynamic behavior
  changes

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Preparation

• Read assignment document
• Download materials for Milestone 1
• milestone1.zip
• Unzip into empty directory
• Open DrJava
• Copy your drjava.jar into the project directory

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Configuring DrJava

• Add RiceMBSfw.jar file to Extra Classpath
• Edit, Preferences, Resource Locations
• Click on Add button
• Click on RiceMBSfw.jar file and Select
• Click on OK at the bottom of the dialog
• Now the framework has been added and can be used
  without source
• Make sure you run in Full Java

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Running the Simulation

• In the Interactions pane, type
• java controller.MBSController
• Play around with the simulation
• Create new environment
• Edit environment
• Add fish
• Run simulation

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Part 1 KnightFish

• Randomly pick one of 8 targets
• Example 3

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3
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Part 1 KnightFish

• Turn into right direction
• Attempt one step forward
• If blocked, done
• If open, go there

3
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Part 1 KnightFish

• Attempt a second step
• If blocked, done
• If open, go there
• Turn into right direction

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Part 1 KnightFish

• Attempt the third and last step
• If blocked, done
• If open, go there

3
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Part 1 KnightFish

• Moves almost like a knight, except
• No jumping
• If blocked, might stop on the way

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Stop here
Stop here
Stop here
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Part 1 KnightFish

• Complicated behavior
• Procedural programming many nested if-statements
• Delegation method
• Nested visitors
• Cannot forget to handle a situation (compiler
  error!)
• Process flow diagramming
• Makes designing complex algorithm a systematic
  process

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Part 1 KnightFish

• Students do this assignment
• Most of the code can be taken from existing
  examples
• For lack of time, we will do something simpler
• Fish attempts to move forward
• If blocked, turn around 180 degrees
• If open, go there
• Open TeachFish.java in model.fish

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Part 1 KnightFish
Ask local environment to move forward
protected void move() tryMoveFwd( ,
)
new ILambda() public Object
apply(Object notUsed)
turnRight(Math.PI) return null
Command to execute if blocked
new ILambda() public Object apply(Object
moveCmd) ((ILambda)moveCmd).apply(null)
return null
((ILambda)moveCmd).apply(null)
Command to execute if unblocked
Tell the local environment to actually move the
fish
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Part 1 KnightFish

• Compile the file
• Run the simulation
• Create a new environment, and edit it
• Add a fish
• Select Add
• Enter model.fish.TeachFish and hit Create
• Click somewhere on the map
• Run the simulation

New fish class loaded at runtime!
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Part 2 WrappingEnv

• Grid-based, bounded, and rectangular environment
• If the fish leaves on one side, it re-enters from
  the other side
• Topology torus (donut)

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Part 2 WrappingEnv

• Very similar to BoundedEnv
• In BoundedEnv, the Location class computes a
  neighboring location by adding a direction
  vector to its own coordinates.
• The new coordinates might be inside or outside
  the environment.
• Can new coordinates ever be outside in
  WrappingEnv?

Answer is part of class assignment and has been
removed
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Part 2 WrappingEnv

• The leftmost x-coordinate that is still inside
  the environment is 0. The rightmost one is
  (width-1).
• In BoundedEnv, the x-coordinate of the neighbor
  from there to the left is -1.
• Whats the x-coordinate of the left neighbor in
  WrappingEnv?

Answer is part of class assignment and has been
removed
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Part 2 WrappingEnv

• The necessary changes are centralized in a single
  method, WrappingEnv.Location.getNeighbor.
• Since BoundedEnv and WrappingEnv are so similar,
  what OO technique can we apply to maximize
  code-reuse?

Answer is part of class assignment and has been
removed
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Part 2 WrappingEnv

• Need to write constructors
• The framework uses factory methods
• Abstract creation
• To complete the environment, we have to override
  the factory methods
• WrappingEnv.makeLocation
• WrappingEnv.makeEnvFactory (code provided for
  makeEnvFactory)
• Students code is still based on existing code,
  but cannot simply be copied and modified anymore

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Part 2 WrappingEnv

• Open WrappingEnv.java in sysModel.env
• The project was split into model and a
  sysModel packages to clearly separate system
  code (environments) from user code (fish)
• Fish more likely to get changed than environments
• Edit the WrappingEnv.Location.getNeighbor method
• Students would have to do a little bit more

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Part 2 WrappingEnv

• Code is part of a class assignment
• and has been removed

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Part 2 WrappingEnv

• Compile the file
• Run the simulation
• Create a new environment
• Select Add
• Enter sysModel.env.WrappingEnv and hit Create
• Pick a size and create the environment
• Add fish
• Run the simulation

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End of Milestone 1

• Students submit code for Part 1 and Part 2
• Material for Milestone 2 gets released after
  submission deadline
• Contains solutions for Milestone 1