Java:JGraphT add edges using a loop

Is it possible to add edges to a graph through the use of a loop? I am parsing a String to determine the appropriate edges and labels. For some reason it will only add the edge for the first round of the while loop used to iterate through the String. For all of the others the following message appears...

Warning: an edge was deleted because the underlying JGraphT graph refused to create it. This situation can happen when a constraint of the underlying graph is violated, e.g., an attempt to add a parallel edge or a self-loop to a graph that forbids them. To avoid this message, make sure to use a suitable underlying JGraphT graph.

import java.awt.*;
import java.awt.geom.*;

import javax.swing.*;

import org.jgraph.*;
import org.jgraph.graph.*;

import org.jgrapht.*;
import org.jgrapht.ext.*;
import org.jgrapht.graph.*;

// resolve ambiguity
import org.jgrapht.graph.DefaultEdge;

public class JGraphAdapterDemo
    extends JApplet
{

    private static final long serialVersionUID = 3256444702936019250L;
    private static final Color DEFAULT_BG_COLOR = Color.decode("#FAFBFF");
    private static final Dimension DEFAULT_SIZE = new Dimension(530, 320);

    static ListenableGraph<String, String> g =
        new ListenableDirectedMultigraph<String, String>(String.class);

    static int [] finalStates = new int[10];
    static int startState = 0;
    static char tran = ' ';
    static int endState = 0;

    private JGraphModelAdapter<String,String> jgAdapter;

    public static void main(String [] args)
    {
        JGraphAdapterDemo applet = new JGraphAdapterDemo();
        applet.init();

        JFrame frame = new JFrame();
        frame.getContentPane().add(applet);
        frame.setTitle("JGraphT Adapter to JGraph Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }

    public void init()
    {
        // create a JGraphT graph
        ListenableGraph<String, String> g =
            new ListenableDirectedMultigraph<String, String>(String.class);

        // create a visualization using JGraph, via an adapter
        jgAdapter = new JGraphModelAdapter<String, String>(g);

        JGraph jgraph = new JGraph(jgAdapter);

        adjustDisplaySettings(jgraph);
        getContentPane().add(jgraph);
        resize(DEFAULT_SIZE);

        int numStates = 4;
        int numSymbols;
        int currentState;
        int i = 0;

            String input = "4 2 0 2 -1 0 a 1 1 b 3 2 c 2 3 c 3 -1";     //place input String here
            int readInt = 0;
            int j = 0;
            String str = "";
            int place = 0;
            String fState;

            //read in numStates, numSymbols, initialState
            i=0;

            //parse string 
            i = input.indexOf(" ",0);

            str = input.substring(0,i); //number of states
            numStates = Integer.parseInt(str);  //convert to int

            for(int k = 0; k< numStates; k++){
                g.addVertex("q"+k);
            }

            i++;
            j = i;

            i=input.indexOf(" ",j);

            str = input.substring(j,i); //number of symbols
            numSymbols = Integer.parseInt(str);

            i++;
            j = i;

            i=input.indexOf(" ",j);

            str = input.substring(j,i); //initial state
            currentState = Integer.parseInt(str);   

            i++;
            j = i;      

            //read in finalStates
            while(readInt!=-1){
                i=input.indexOf(" ",j);
                fState = input.substring(j,i);  //a final state
                readInt = Integer.parseInt(fState);
                if(readInt!=-1){
                    finalStates[place] = readInt;
                    i++;
                    j = i;
                    place++;
                }//end if
            }//end while
            i++;
            j = i;

            String sState;
            String eState;

            while(startState!=-1&& j<(input.length()-2)){           //until end of file
                i=input.indexOf(" ",j);
                sState = input.substring(j,i);  //start state
                startState = Integer.parseInt(sState);  //convert to int
                if(startState!=-1){             
                    i++;
                    j = i;

                    String cStr = "";
                    tran = input.charAt(i);         //transition
                    cStr = cStr + tran;
                    i = i+2;
                    j=i;        

                    i=input.indexOf(" ",j); 
                    eState = input.substring(j,i);      //end state
                    endState = Integer.parseInt(eState);

                    i++;
                    j=i;
                    String one = "q"+startState;
                    String two = "q"+endState;
                    System.out.println(one+ two +" "+cStr);
                    g.addEdge(one, two, cStr);

                    //drawEdge(one, two, cStr);

                }//end if

            }//end while

    }

    public static void drawEdge(String v, String v1, String label){
        System.out.println(v +" "+v1+ " "+label);
        g.addEdge(v,v1,label);
    }

    private void adjustDisplaySettings(JGraph jg)
    {
        jg.setPreferredSize(DEFAULT_SIZE);

        Color c = DEFAULT_BG_COLOR;
        String colorStr = null;

        try {
            colorStr = getParameter("bgcolor");
        } catch (Exception e) {
        }

        if (colorStr != null) {
            c = Color.decode(colorStr);
        }

        jg.setBackground(c);
    }

    @SuppressWarnings("unchecked") // FIXME hb 28-nov-05: See FIXME below
    private void positionVertexAt(Object vertex, int x, int y)
    {
        DefaultGraphCell cell = jgAdapter.getVertexCell(vertex);
        AttributeMap attr = cell.getAttributes();
        Rectangle2D bounds = GraphConstants.getBounds(attr);

        Rectangle2D newBounds =
            new Rectangle2D.Double(
                x,
                y,
                bounds.getWidth(),
                bounds.getHeight());

        GraphConstants.setBounds(attr, newBounds);

        // TODO: Clean up generics once JGraph goes generic
        AttributeMap cellAttr = new AttributeMap();
        cellAttr.put(cell, attr);
        jgAdapter.edit(cellAttr, null, null, null);
    }

    //~ Inner Classes ----------------------------------------------------------

    /**
     * a listenable directed multigraph that allows loops and parallel edges.
    // */
    private static class ListenableDirectedMultigraph<V, E>
    extends DefaultListenableGraph<V, E>
    implements DirectedGraph<V, E>
    {
    private static final long serialVersionUID = 1L;

    ListenableDirectedMultigraph(Class<E> 开发者_运维问答edgeClass)
        {
        super(new DirectedMultigraph<V, E>(edgeClass));
        }
    }


}

If you want to use a graph that allows loops you have to create an abstract class "AbstractBaseGraph". For this reason you have to create another class that extends your super class. Here's an example.

public class MiGrafo
extends AbstractBaseGraph<String, DefaultEdge>
implements DirectedGraph<String, DefaultEdge> {

public MiGrafo() {// EdgeFactory<String, DefaultEdge> arg0, boolean arg1,boolean arg2
    super(new ClassBasedEdgeFactory<String, DefaultEdge>(
            DefaultEdge.class),
        true,
        true);
    // TODO Auto-generated constructor stub
}

}

In addition you have to implement a directed or undirected graph follow of your extends.

When you create the new graph that allows using loops you only have to write this sentence:

MiGrafo h = new MiGrafo();

Finally you only have to use the graph like a simple graph.

See you.