EECS 293  Software Craftsmanship 2013 Fall Semester  Programming Assignment 4   

Programming First, make any changes that were discussed in your recitation session.  A common error handling technique is to use a status variable (for example, pages 403404: “Rewrite with a status variable”). In this assignment, you will rewrite MazeCell so that it prevents time values that are zero or negative, and uses a status variable to communicate potential errors. First, define a class Status nested within MazeCell:  Status contains a public enumerated type called Code with values OK, ALREADY_VALID, INVALID_TIME. Each code has an associated String description that can be retrieved with a method called getMessage. A tutorial on Java enums is posted on blackboard.   Status() a constructor that initializes the status to OK. It must throw no exceptions.  void set(Code code) and Code get() to set and get the current status. Then, rewrite MazeCell with:   void addPassages(Map<MazeCell, Integer passages, Status status) sets up the outgoing passages from this MazeCell, and makes this MazeCell valid. The first argument gives the travel time along a passage from this MazeCell to another MazeCell in seconds. A travel time equal to MAX_VALUE represents an impassable connection. If this MazeCell had already been connected with some passages (that is, this MazeCell was already valid), the method does nothing but it sets status to ALREADY_VALID. If any travel time is zero or negative, the status will be INVALID_TIME. Otherwise, the status will be OK.  Since different lab mice may take different lengths of time to clear the obstacles from one cell to another, the passage time can be random. Specifically, suppose that the passage time can vary randomly between 1 second and the value given in the MazeCell. An 
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introduction to random numbers in Java is posted on blackboard. Implement the following additional MazeRoute method:  Integer travelTimeRandom() returns the time needed to follow this route assuming that on each passage the mouse takes a random time between 1 second and the value given in the corresponding MazeCell. However, if the route contains an impassable (one with MAX_VALUE travel time) or invalid passage, it returns MAX_VALUE. It returns 0 if the route consists of only one cell. The method throws a UninitializedObjectException if this MazeRoute is invalid. Moreover, implement the following additional Maze method:  MazeRoute routeRandom(MazeCell initialCell) returns a route within the maze starting from and including the given initial cell assuming that in each cell the mouse chooses a random passage (if a cell has n outgoing passages, the mouse will choose one of the n passages at random). The mouse should never cross a passage whose travel time is MAX_VALUE. The route should stop if the mouse exits the maze, reaches a dead end, or reaches a cell that it had previously visited.  It returns an empty list in case of error, for example if at any point the mouse finds itself in a cell that does not belong to the maze (either at the initial cell or throughout the route). The method throws a UninitializedObjectException if this Maze is invalid. Create a test case where routeRandom can produce a different path than routeFirst even if started from the same initialCell, and an example where the two methods must always produce the same path. As usual, these classes may contain as many auxiliary private methods as you see fit, and additional helper classes may be defined. Your classes must be documented in JavaDoc. Test cases must be created in JUnit to test all its public methods. 
Discussion Guidelines The class discussion will focus on:  High-level code organization  The design and documentation of your project  Functions that exceed McCabe’s complexity of 4 (if any)  Non-structured programming constructs and break statements (if any)  The difference between an arbitrary choice and a random choice. On-Line Submission Bring a copy to recitation to display on a projector. Additionally, submit an electronic copy of your program to blackboard. Turn in with your code:  A README file explaining how to compile and run the code.  A Make, Ant, or Maven build file that works with both Java.  A comment at the top over file containing your name, email address, a one-sentence description of the file, and if necessary a longer comment describing the design of the file. 
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The code should be handed in a zip, tar.bz2, or tar.gz archive. Archives in 7z cannot be accepted.  
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