Homework #7

• Exercise P8.2 and P8.6. The String toString() method returns a string; it doesn't print it. Submit two files, Purse.java and PurseTester.java. Your tester class must contain at least two non-trivial test cases.
• Exercise P8.8. Submit two files, Polygon.java and PolygonComponent.java (as in homework 4). Use this runner program:

  import javax.swing.JFrame;
  
  public class ExP8_8
  {
     public static void main(String[] args)
     {
        JFrame frame = new JFrame();
  
        final int FRAME_WIDTH = 500;
        final int FRAME_HEIGHT = 500;
  
        frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        frame.setTitle("ExP8_8");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
        PolygonComponent component = new PolygonComponent();
        frame.add(component);
  
        frame.setVisible(true);
     }
  }
  

• Exercise P8.16. Submit TicTacToe.java and TicTacToeTester.java. Your tester class must contain at least two non-trivial test cases.
• Project P8.2. We will use GridWorld for a graphical display. Follow this outline:

  import info.gridworld.grid.Grid;
  import info.gridworld.grid.Location;
  import info.gridworld.world.World;
  
  public class LifeWorld extends World<String>
  {
      public void step()
      {
          // your work goes here
      }
  
      // This method lets the user click on a location 
      // to toggle its content
      public boolean locationClicked(Location loc)
      {
          Grid<String> grid = getGrid();
          if (grid.get(loc) == null) // empty 
              grid.put(loc, "?");
          else
              grid.remove(loc);
          return true;
      }      
  }
  

  You also need a runner program such as this one:

  import info.gridworld.grid.UnboundedGrid;
  
  public class LifeWorldRunner
  {
      public static void main(String[] args)
      {
          LifeWorld world = new LifeWorld();
          world.setGrid(new UnboundedGrid<String>());
          world.show();
      }
  }
  

  You need to implement the step method so that it calculates the next generation. Use the Grid methods
  • getOccupiedLocations
  • getNeighbors
  See the javadoc for details. Calling grid.getNeighbors(loc).size() gets you the count of neighbors.
  CAUTION: This is a bit harder than it sounds--you cannot simply add or remove occupants as soon as the count matches the rules. That would affect other counts. Instead, keep two array lists

  ArrayList<Location> aboutToDie = new ArrayList<Location>();
  ArrayList<Location> aboutToBeBorn = new ArrayList<Location>();

  Fill them with the appropriate locations. At the end of the step method, process them:

  for (Location loc : aboutToDie) grid.remove(loc);
  for (Location loc : aboutToBeBorn) grid.put(loc, "?");     

  To test your class, simply add cells to your world (by calling world.getGrid().put(loc, "?")), call step, and check that the correct locations are occupied (by calling world.getGrid().get(loc)).
  Submit LifeWorld.java and LifeWorldTester.java
  

Submit a zip file hw7_xyzw with the files

• Purse.java, PurseTester.java
• Polygon.java, PolygonComponent.java
• TicTacToe.java, TicTacToeTester.java
• LifeWorld.java, LifeWorldTester.java