import java.util.*;

public class Screen
{
    public Screen ()
    {
        _tiles = new Vector<Tile>();
    }

    public final void updateTile (Coordinate position, int id)
    {

    }

    private Vector<Tile> _tiles;
}
@@ -55,16 +55,29 @@
 Screen (
+boolean debug
 )%0A    %7B%0A
@@ -113,16 +113,40 @@
 ile%3E();%0A
+        _debug = debug;%0A
     %7D%0A%0A 
@@ -182,43 +182,479 @@
 le (
-Coordinate position, int id)%0A    %7B%0A
+Tile theTile)%0A    %7B%0A        int index = _tiles.indexOf(theTile);%0A%0A        if (index != -1)%0A            _tiles.set(index, theTile);%0A        else%0A            _tiles.add(theTile);%0A    %7D%0A%0A    public final int numberOfBlocks ()%0A    %7B%0A        Enumeration%3CTile%3E iter = _tiles.elements();%0A        int count = 0;%0A%0A        while (iter.hasMoreElements())%0A        %7B%0A            if (iter.nextElement().getId() == TileId.BLOCK)%0A                count++;%0A        %7D%0A%0A        return count;
 %0A   
@@ -690,9 +690,37 @@
 _tiles;%0A
+    private boolean _debug;%0A
 %7D

Update Screen.java