©2010 Felleisen, Proulx, et. al.

5  Abstracting over Data Definitions, Methods

Portfolio Problems

Work out as complete programs the following exercises from the textbook. Make sure you read the textbook to get a guidance how to proceed.

Problems:

1. Problem 19.5 on page 271

2. Problems 19.6 - 19.11 on page 276-279

   You may complete this part with animation using the draw library.

Pair Programming Assignment

Note: Please,use the latest version of tester. It has been posted on February 9, 2010 at 12:32 pm.

5.1  Problem

Design the class CartPt that extends the geometry library class Posn. We will not add any new fields, but by extending the library class we can add new methods to it.

Design the following methods for the class CartPt:

• Method distTo that computes the distance from this point to the given one.

• Method fromTo that produces a String that tells us in which direction do we have to travel from this point to the given one. Make sure you cover the following possibilities:

  going North, East, West, South, Northwest, Northeast, Southwest, and Southeast.

5.2  Problem

The following class diagram describes data definitions that represent a state map:

Each place has a unique name, a location, and a list of neighbors (only their names). The state map is a list of places.

     +-------------+
     | StateMap    |
     +-------------+
     | ILoP places |---+
     +-------------+   |
          +------------+
          |
          v
      +-------+
      | ILoP  |<-----------+
      +-------+            |
          / \              |
          ---              |  
           |               |
     ----------------      |
     |              |      |
 +-------+ +-------------+ |    
 | MtLoP | | ConsLoP     | |
 +-------+ +-------------+ |    
        +--| Place first | |
        |  | ILoP  rest  |-+
        |  +-------------+
        v
   +----------------+
   | Place          |
   +----------------+
   | String name    |
   | CartPt loc     |
   | ILoN neighbors |--+
   +----------------+  |
           +-----------+
           |
           V
       +-------+  
       | ILoN  |<-----------+     
       +-------+            |                     
          / \               |    
          ---               |
           |                |           
    --------------          |        
    |            |          |    
 +-------+ +--------------+ |        
 | MtLoN | | ConsLoN      | |  
 +-------+ +--------------+ |     
           | String first | |              
           | ILoN   rest  |-+               
           +--------------+              

• Make a simple map with at least ten places for your example and show how it looks. It can be ASCII art included in your code, or a Canvas drawing, or a sketch turned into a .png file. The following is a sample map:

                         Dedham --------------------- Boston
                       /    |                        / |
                     /      |                      /   |
            Wellesley       |                    /     |
               |            |                  /       |
               |            |                /         |
            Franklin --- Canton ------- Milton         |
           /      \         |   \         |            |
         /         \        |     \       |        Plymouth
       /            \       |       \     |       /
  Sharon             \      |         New Bedford
                      \     |
                       Providence
  
  

Design the following methods for the classes that represent the state map:

• Method totalDistance that computes the total distance for the route that is given as a list of names. Throw IllegalArgumentException if the name is not a name of a place in the state maps list of places.

• Method hasLoop that determines whether the given route goes through one of the cities more than once.

• Method directions that produces a list of Strings that tell us how to get from one place to another one, following the chosen route.

  For example, the directions could be:

  "From Harvard Square to Boston Common"
  "Go Southeast 1.2 miles to Central Square"
  "Go Southeast 0.5 miles to Mass Ave and Main Street"
  "Go East 1.3 miles to Longfellow Bridge"
  "Go East 0.5 miles to MGH"
  "Go South 0.5 miles to Boston Common"
  

• Extra Credit – required for students in the Honors Seminar
  Display the route on the Canvas. Animate the route using slow tick rate, so the user can see where to go - possibly displaying the routing String at the bottom of the Canvas.