Removed Boshart's Reference Queue implementation for an ArrayList. Also fixed a few bugs with the interface and diameter methods.

Graph.java

@@ -65,6 +65,18 @@ public class Graph	{
 		return ( size == 0 );
 	}
 	
+	/**
+	 * Determines if this graph is a connected graph or not.
+	 * @return boolean determining if this is connected.
+	 */
+	public boolean isConnected()	{
+		for ( int x = 0; x < size; x++ )	{
+			ArrayList t = bft ( getVertex ( x ).getKey() );
+			if ( t.size() != size )	return false;
+		}
+		return true;
+	}
+	
 	/**
 	 * Convienence method for determining the number of vertecies in the graph.
 	 * @return int of the size of the graph.pat
@@ -333,18 +345,17 @@ public class Graph	{
 	public ArrayList bft ( Comparable searchKey )	{
 		GraphNode temp;
 		ArrayList searchList = new ArrayList();
-		QueueReferenceBased bfsQueue = new QueueReferenceBased();
+		ArrayList bfsQueue = new ArrayList ( size );
-		bfsQueue.enqueue ( vertexList.get ( findIndex ( searchKey ) ) );
+		bfsQueue.add ( bfsQueue.size(), vertexList.get ( findIndex ( searchKey ) ) );
 		getVertex ( searchKey ).setMarked ( true );
 		searchList.add ( getVertex ( searchKey ) );
 
 		while ( !bfsQueue.isEmpty() )	{
-			temp = (GraphNode)bfsQueue.dequeue();
+			temp = (GraphNode)bfsQueue.remove ( 0 );
-
 			for ( int g = 0; g < size; g++ )	{
 				if ( adjacent[findIndex ( temp.getKey() )][g] != Double.POSITIVE_INFINITY && !getVertex ( g ).isMarked() )	{
 					((GraphNode)vertexList.get ( g )).setMarked ( true );
-					bfsQueue.enqueue ( vertexList.get ( g ) );
+					bfsQueue.add ( bfsQueue.size(), vertexList.get ( g ) );
 					searchList.add ( getVertex ( g ) );
 				}
 			}
@@ -358,22 +369,27 @@ public class Graph	{
 	 * @return int representing the diameter of the graph.
 	 */
 	public double diameter()	{
+		// early check... can make it take a really long time
+		if ( !isConnected() )	return Double.POSITIVE_INFINITY;
+		System.out.println ( "Graph is connected." );
 		double mins[] = new double[size];
+		// find all shortest paths and determine the maximum of each
 		for ( int x = 0; x < size; x++ )	{
-			mins[x] = 0;
+			mins[x] = 0.0;
-			ArrayList t = bft ( getVertex ( x ).getKey() );
+			Comparable key = getVertex ( x ).getKey();
-			if ( t.size() != size )	return Double.POSITIVE_INFINITY;
+			for ( int y = 0; y < size; y++ )	{
-			for ( int y = 1; y < t.size(); y++ )	{
+				if ( x == y )	continue;
-				mins[x] += getWeight ( ((GraphNode) t.get ( y - 1 )).getKey(), ((GraphNode) t.get ( y )).getKey() );
+				ArrayList path = shortestPath ( key, getVertex ( y ).getKey() );
+				if ( path.size() > mins[x] )	mins[x] = path.size();
 			}
 		}
-		
+		// find the minimum of the paths
-		double minsize = mins[0];
+		double max = mins[0];
 		for ( int x = 0; x < size; x++ )	{
-			if ( minsize > mins[x] )
+			if ( mins[x] > max )	max = mins[x];
-				minsize = mins[x];
 		}
-		return minsize;
+		// return num edges between them, not number of nodes
+		return max - 1;
 	}
 	
 	/**
@@ -395,7 +411,7 @@ public class Graph	{
 		}
 		else	{
 			ArrayList q = new ArrayList ( x );
-			for ( int y = 0; y < x; y++ )
+			for ( int y = 0; y <= x; y++ )
 				q.add ( p.get ( x ) );
 			p = q;
 		}
@@ -473,6 +489,7 @@ public class Graph	{
 					smallest = j;
 					smallestweight = weight[j];
 				}
+			//if ( smallest == -1 )	continue;
 			/* mark smallest vertex */
 			GraphNode smallnode = (GraphNode)vertexList.get ( smallest );
 			smallnode.setMarked ( true );
@@ -502,6 +519,9 @@ public class Graph	{
 		/* gotta add the first one */
 		result.add ( getVertex ( firstkey ) );
 		
+		/* unmark everything */
+		clearMarks();
+		
 		/* reverse the arraylist */
 		path.clear();
 		for ( int i = result.size() - 1; i >= 0; i-- )

GraphDriver.java

@@ -52,7 +52,9 @@ public class GraphDriver	{
 				
 				//get all the actors in a usable form
 				line = read.readLine();
-				while ( !line.equals ( "" ) )	{
+				// NEW
+				// added check for read.ready() : no longer must have two lines ending input file
+				while ( read.ready() && !line.equals ( "" ) )	{
 					actors.add ( line );
 					line = read.readLine();
 				}
@@ -113,9 +115,8 @@ public class GraphDriver	{
 				command = in.readLine().trim();
 			}
 			catch ( IOException exception )	{
-				System.out.println ( "bailing from:" );
+				System.out.println ( "bailing from command:" );
 				exception.printStackTrace();
-				break;
 			}
 			if ( command.equals( "path" ) )	{
 				System.out.print ( "actors (one,two)> " );
@@ -124,16 +125,17 @@ public class GraphDriver	{
 					actors = (String [])in.readLine().trim().split ( "," );
 				}
 				catch ( IOException exception )	{
-					System.out.println ( "bailing from:" );
+					System.out.println ( "bailing from path:" );
 					exception.printStackTrace();
-					break;
 				}
 				if ( actors.length != 2 )	{
 					System.out.println ( "Enter two actors only!" );
 				}
+				else	{
 					ArrayList path = mygraph.shortestPath ( actors[0].trim(), actors[1].trim() );
 					printPath ( path );
 				}
+			}
 			else if ( command.equals( "bfs" ) )	{
 				System.out.print ( "actors (one,two)> " );
 				String actors[] = null;
@@ -141,17 +143,17 @@ public class GraphDriver	{
 					actors = (String [])in.readLine().trim().split ( "," );
 				}
 				catch ( IOException exception )	{
-					System.out.println ( "bailing from:" );
+					System.out.println ( "bailing from bfs:" );
 					exception.printStackTrace();
-					break;
 				}
 				if ( actors.length != 2 )	{
 					System.out.println ( "Enter two actors only!" );
 				}
-				//put in real bfs here for two states
+				else	{
 					ArrayList path = mygraph.bfs ( actors[0].trim(), actors[1].trim() );
 					printPath ( path );
 				}
+			}
 			else if ( command.equals ( "add" ) )	{
 				System.out.print ( "read from file> " );
 				String filename[] = null;
@@ -159,9 +161,8 @@ public class GraphDriver	{
 					filename = (String [])in.readLine().trim().split ( " " );
 				}
 				catch ( IOException exception )	{
-					System.out.println ( "bailing from:" );
+					System.out.println ( "bailing from add:" );
 					exception.printStackTrace();
-					break;
 				}
 				for ( int q = 0; q < filename.length; q++ )	{
 					readFile ( filename[q], q, filename.length );
@@ -174,6 +175,9 @@ public class GraphDriver	{
 			else if ( command.equals ( "quit" ) )	{
 				break;
 			}
+			else	{
+				System.out.println ( "Unknown Command: '" + command + "'" );
+			}
 			System.out.println();
 		}
 	}