Thread: Issue Building Graph in Adjacency Matrix

Hey guys and girls,

Somewhat stuck on this program. Im building an Adjacency Matrix and I cant seem to figure out how to create my buildGraph method. The whole program won't fit here so I have attached the netbeans project folder.

Here is essentially what needs work:

    public void buildGraph()
    {
      //  v.getIncidentEdges();
       // w.getIncidentEdges();
        for (int x = 1; x <10; x++){
            for (int y = 1; y<10; y++){
            /*
             * This needs help for sure. Im trying to check the Vertex to the
             * left, and the vertex above, and if they arent null, then create
             * and edge with them. 
             * Moving through a 10x10 grid of Vertices creating edges between
             * them.
             * 
             *   if (Vertices != null && Vertices != null){
             */    
                    try {g.addEdge(v, w);}catch (NullPointerException npe) {}
                 }
            }
        }

Here is the addEdge method:

      public Edge addEdge(Vertex v,Vertex w) {
          Edge e = new Edge(v, w);
          v.addIncidentEdge(e);
          w.addIncidentEdge(e);
          e.getDestVertex();
          e.getOriginVertex();
          Edges.add(e);
          return e;
 
    }

Here is the addVertex method:

      public Vertex addVertex(Cell c){
        Coordinate z = c.getCoordinate();
        int x = z.getX();
        int y = z.getY();
        Vertex v = new Vertex(c);
        try {Vertices.add(v);}catch (NullPointerException npe) {}
        System.out.println("("+ x + "," + y + ")" );
        return v;
      }

Here is how I'm adding the vertices, essentially everytime it creates a new cell, it adds a vertex there, except when we add an Agent cell, for later when moving through the Matrix it wont be possible to walk into the agents:

if ((coordinate).equals(generator.getNeo())){
                    cell = new Cell(CellType.Neo,coordinate);
                    System.out.println(CellType.Neo + " Vertex");
                    g.addVertex(cell);
 
                }
                else if(coordinate.equals(generator.getMorpheus())){
                    cell = new Cell(CellType.Morpheus,coordinate);
                    System.out.println(CellType.Morpheus + " Vertex");
                    g.addVertex(cell);
 
                }
 
                else if(coordinate.equals(generator.getPhoneBooth())){
                    cell = new Cell(CellType.PhoneBooth,coordinate);
                    System.out.println(CellType.PhoneBooth + " Vertex");
                    g.addVertex(cell);
 
                }
                else if (generator.getAgents().contains(coordinate)){
                    cell = new Cell(CellType.Agent,coordinate);
                    System.out.println(CellType.Agent);
                    System.out.println(coordinate);
                }
                else
                {
                    cell = new Cell(CellType.Blank,coordinate);
                    System.out.println(CellType.Blank + " Vertex");
                    g.addVertex(cell);
                }

Again, the code in its entirety is attached. There are multiple classes and didnt exactly want to post every last peice of code here.

Thanks in advance for the help

I am storing the Vertices and the Edges in ArrayLists
here is my graph class:

package matrix;
 
import java.util.ArrayList;
 
public class Graph {
 
    public ArrayList<Vertex> Vertices;
    public ArrayList<Edge> Edges;
 
 
    public Graph() {
 
      ArrayList<Vertex> Vertices = new ArrayList<Vertex>();
      ArrayList<Edge> Edges = new ArrayList<Edge>();
 
      }
 
      public Vertex addVertex(Cell c){
        Coordinate z = c.getCoordinate();
        int x = z.getX();
        int y = z.getY();
        Vertex v = new Vertex(c);
        try {Vertices.add(v);}catch (NullPointerException npe) {}
        System.out.println("("+ x + "," + y + ")" );
        return v;
      }
 
      public Edge addEdge(Vertex v,Vertex w) {
          Edge e = new Edge(v, w);
          v.addIncidentEdge(e);
          w.addIncidentEdge(e);
          e.getDestVertex();
          e.getOriginVertex();
          Edges.add(e);
          return e;
 
    }
 
 
}

because its an ArrayList this is what ive tryed to do for buildGraph:

    public void buildGraph()
    {
 
         if (g.Vertices -1 != null && g.Vertices -10 != null){
                g.addEdge(v,w);
         }
 
    }

Im not really comfortable with array lists, so im a little confused how to move through-out them. That above method is giving me an error, cant use int with Vertex. Also for the g.addEdge(v,w); line im a little confused about where to pull my v and w from at this point.

so I would essentially use this new method to check the vertex before and above? is there no way to move around the ArrayList without creating a new method?

With the new method, I would loop through to check all the Vertices and add edges as I go through them, no?

Just for reference, here is my Edge class and my Vertex class:


Edge:

package matrix;
 
/**
 *
 * @author Sunny
 */
public class Edge {
 
    private Vertex originVertex;
    private Vertex destVertex;
 
    public Edge(Vertex origin, Vertex destination)
    {
        originVertex = origin;
        destVertex = destination;
    }
 
    public Vertex getOriginVertex() { return originVertex; }
    public Vertex getDestVertex() { return destVertex; }
 
    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Edge other = (Edge) obj;
        if (this.originVertex != other.originVertex && (this.originVertex == null || !this.originVertex.equals(other.originVertex))) {
            return false;
        }
        if (this.destVertex != other.destVertex && (this.destVertex == null || !this.destVertex.equals(other.destVertex))) {
            return false;
        }
        return true;
    }
 
    @Override
    public int hashCode() {
        int hash = 5;
        hash = 97 * hash + (this.originVertex != null ? this.originVertex.hashCode() : 0);
        hash = 97 * hash + (this.destVertex != null ? this.destVertex.hashCode() : 0);
        return hash;
    }
 
    public String toString()
    {
        String s = "";
        s = "Origin: " + originVertex.toString();
        s += "\n";
        s += "Destination: " + destVertex.toString();
 
        return s;
    }
}

Vertex:

package matrix;
 
import java.util.ArrayList;
 
/**
 *
 * @author Sunny
 */
public class Vertex {
 
    private Cell _element;
    private ArrayList<Edge> incidentEdges;
 
    public Vertex()
    {
        _element = null;
        incidentEdges = new ArrayList<Edge>();
    }
    public Vertex(Cell element)
    {
        _element = element;
        incidentEdges = new ArrayList<Edge>();
    }
    public Vertex(Cell element, ArrayList<Edge> edges)
    {
        incidentEdges = new ArrayList<Edge>();
        for (Edge e : edges)
                incidentEdges.add(e);
    }
 
    //Get or Set Element
    public void setElement(Cell element) {_element = element;}
    public Cell getElement() { return _element; }
 
    //Get Incident Edges
    public ArrayList<Edge> getIncidentEdges() { return incidentEdges; }
    //Add an incident Edge
    public void addIncidentEdge(Edge e) { if (!incidentEdges.contains(e)) incidentEdges.add(e); }
 
    public void removeEdge(Vertex v)
    {
        for (int i=incidentEdges.size()-1; i>=0; i--)
        {
            Edge e = incidentEdges.get(i);
            if (e.getDestVertex().equals(v) && e.getOriginVertex().equals(this))
            {
                incidentEdges.remove(i);
                break;
            }
            else if (e.getDestVertex().equals(this) && e.getOriginVertex().equals(v))
            {
                incidentEdges.remove(i);
                break;
            }
        }
    }
 
    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Vertex other = (Vertex) obj;
        if (this._element != other._element && (this._element == null || !this._element.equals(other._element))) {
            return false;
        }
        return true;
    }
 
    @Override
    public int hashCode() {
        int hash = 7;
        hash = 31 * hash + (this._element != null ? this._element.hashCode() : 0);
        return hash;
    }
 
 
}