Data handling and graphs

Question

I originally wrote the graph program to handle the data in a text file that was organized like this...
vertex a
vertex b
vertex c
vertex d
edge a c
edge a d
edge d b
and now I have to change the main to accept a datafile containing...
a b
b c
c e
d g
g c
Now, here is a copy of the main program as it currently stands...
import java.io.*;
import java.util.*;
public class TopSort
     static Graph theGraph = new Graph();
     static Hashtable hashList = new Hashtable();  //just to store array index
     public static void main (String args[])
             MyInfoachaffin myInfo = new MyInfoachaffin();
          myInfo.info();     
             File sourceFile = new File(args[0]); // access the file
             if (sourceFile.exists() == false)                                          
               System.err.println("Oops: " + sourceFile + ": No such file");
               System.exit(1);
             String newVertex, startEdge, endEdge;
             int arrayPosition = -1;
             try //open the file
                       FileReader fr = new FileReader(sourceFile);
                       BufferedReader br = new BufferedReader(fr);
                    String input;
                    while ((input = br.readLine()) != null)
                         StringTokenizer toke = new StringTokenizer(input);
                            while (toke.hasMoreTokens())
                              if (hashList.containsValue(toke))
                                           return;
                                 else
                                      newVertex = toke.nextToken(); //get vertex
                                      theGraph.addVertex(newVertex); //add into graph
                                      arrayPosition++; //increment counter
                                      hashList.put(newVertex, new Integer(arrayPosition));
                                      //add position with vertex as key
                                 /*else if (toke1.equals("edge"))
                                      startEdge = toke.nextToken(); //get edge
                                      endEdge = toke.nextToken();  //get vertex
                                      Integer temp = ((Integer)hashList.get(startEdge));
                                      int start = temp.intValue(); //find position with key
                                   Integer temp2 = ((Integer)hashList.get(endEdge));
                                      int end = temp2.intValue();  //find position with key
                                      theGraph.addEdge(start, end); //add edge
                            }//close inner while
                   }//close outer while
                   System.out.println("The hashtable contents: " + hashList.entrySet());
                    br.close();
              }//close try
                  catch (IOException e)
                            System.out.println("Whoops, there's a mistake somewhere.");
                      theGraph.graphSort();
   }//end main
}//end class I have managed to seperate the vertexes from the edges and stored them in a hashtable so as to be able to remember their location in the array itself. My question is is there a way to go through a file a second time and pull the vertexes from that file or, conversely, should I store the data in the file into, oh I dunno, a linked list or something that I can pull the data from? The graph part of the program works so I didn't add that file and the setting the vertexes works fine too...I'm just stuck on how to handle the edges, exactly, so does anyone have any advice? Right now, the adding edges is commented out because that was how I handled it with the original data...

Answer 1

Whoa, you're freakin' me out.
All you gotta do is read in the data in a new format. You can either translate the new format to the old format, or you can write a method that creates objects from the new format explicitly. That's all there is to it.