OOSE

Note, there may be more than one principle violated. In the case of more than one, explain each principle; but, don't identify a design principle without very good cause.

For more on the design principles refer to the lecture notes and Chapter 8 of the recommended text, HFOOA&D.

1. (10 points)

   This class is a snippet from a console-based 2D board game implementation (think e.g. Chess or Checkers)

   class Game {
       private Piece[][] board;
       public void move() {
           /* Read user input */
           Point source = readCoordinateFromInput();
           Point dest = readCoordinateFromInput();
           /* Does the source square have a piece? Is the desination empty? */
           if (board[source.x][source.y] == null || board[dest.x][dest.y] != null)
               throw new IllegalMoveException();
           /* ... More rules here .. */
           /* Print out the current state of the board */
           printBoard();
       }
   
       private Point readCoordinateFromInput() {
           /* Read input from the terminal and convert to a point */
       }
       private void printBoard() {
           /* Printing code here */
       }
   }
   

2. (10 points)

   Here is another board game example, this time just code for the board and there are both 2D and 3D boards.

   
   public class Square  {
       int value;
   }
   public class Board {
   
       private Square[][] squares;
       public void updateSquare(int x, int y, Square aSquare) {
           squares[x][y] = aSquare;
       }
   
       public Square getSquare(int x, int y) {
           return squares[x][y];
       }
   
       // ... more methods
   }
   
   public class ThreeDBoard extends Board {
   
       private Square[][][] squares;
       public void updateSquare(int x, int y, int z, Square aSquare) {
           squares[x][y][z] = aSquare;
       }
   
       public Square getSquare(int x, int y, int z) {
           return squares[x][y][z];
       }
   
       // ... more methods
   }
   

3. (10 points)

   This code fragment configures a series of routes for a Javalin server.

   
   Javalin.create()
          .routes(() -> {
                path("step0", () -> { post(myController.stepCode[0]); });
                path("step1", () -> { post(myController.stepCode[1]); });
                path("step2", () -> { post(myController.stepCode[2]); });
                path("step3", () -> { post(myController.stepCode[3]); });
                path("step4", () -> { post(myController.stepCode[4]); });
                path("step5", () -> { post(myController.stepCode[5]); });
            })
   

4. (10 points)

   This code defines an API for interacting with a batch computing cluster.

   
   public interface ClusterManager {
       public int getJobCount();
       public List<JobId> getActiveJobIds();
       public JobId startJob(Job job);
       public double getJobProgress(JobId id);
       public void waitForJobToFinish(JobId id);
       public void pauseJob(JobId id);
       public void resumeJob(JobId id);
       public List<MachineId> getMachineIds();
       public MachineId getMachineIdForJob(JobId id);
       public List<JobId> getJobsOnMachine(MachineId id);
       public double getClusterLoadPercentage();
       public DiagnosticReport runClusterDiagnostics();
       public void restartCluster();
   }
   

5. (10 points)

   This code snippet supports two different databases for some simple operations.

    things)
       {
           for (Object item : things)
           {
               if(item instanceof SqLiteDB)
               {
                   sqLiteSave((SqLiteDB) item);
               }
                   else if(item instanceof PostgresDB)
               {
                   postgresSave((PostgresDB) item);
               }
               logger.info("DB updated");
           }
       }
       private void sqLiteSave(SqLiteDB db) {
       // ... special code for SQLite save
       }
       private void postgresSave(PostgresDB db) {
       // ... special code for Postgres save
       }
   }
   

6. (10 points)

   This is a code fragment for a multi-sensor HVAC (heating / air conditioning) system display

   class HVACController {
       // ...
       void updateDisplay () {
           double tenInsideTemps = 0;
           double tenOutsideTemps = 0.0;
           // implemented in/out temp so far, 
           // still have in/out humidity and 2nd floor temps to go
           for(int i=0; i<10; i++){
               tenInsideTemps = tenInsideTemps + insideSensor.getTemp();
               tenOutsideTemps = tenOutsideTemps + outsideSensor.getTemp();
               TimeUnit.SECONDS.sleep(1); // ten readings to average
           }
           double aveInsideTemp = tenInsideTemps / 10;
           double aveOutsideTemp = tenOutsideTemps / 10;
           display.setInsideTemp(aveInsideTemp);
           display.setOutsideTemp(aveOutsideTemp);
       }
   }

7. (10 points)

   This is code for a simple customer accounts system.

   public class Customer {
       private String firstName;
       private String lastName;
       private String custNumber;
       private double balance = 0;
       // ... getters and setters too
   }
   
   public class Transaction {
       private Date date;
       private String description;
       private double amount;
       // ... getters and setters too
   }
   
   public class Account {
       private String acctId;
       private Customer customer;
       private Transaction[] transactions;
   
       public void deposit(double amount) { // ...
       }
   
       public void withdraw(double amount) { // ...
       }
   
       public double getBal() { // ...
       }
   
       public String getAcctId() { // ...
       }
   
       public void printStatement() { // ... print out all transactions
       }
   }