DirectedGraph: addVertex(Vertex v), String cannot be converted to Vertex

Question

I am trying to learn and implement Directed Graph and facing some difficulties in executing the program.

// ADD Function
public boolean addVertex(Vertex<T> v)
{
    boolean added = false;
    if (verticies.contains(v) == false)
    {
        added = verticies.add(v);
        return true;
    }
    return added;
}

class Vertex<T>
{

    private String name;
    private T data;

    /**
     * Create a Vertex with name n and given data
     *
     * @param n - name of vertex
     * @param data - data associated with vertex
     */
     public Vertex(String n, T data)
     {
         incomingEdges = new java.util.ArrayList<Edge<T>>();
         outgoingEdges = new java.util.ArrayList<Edge<T>>();
         name = n;
         this.data = data;
     }
}

// Initialization of the Vertices & Edges
public GraphImpl()
{
    verticies = new java.util.ArrayList<Vertex<T>>();
    edges = new java.util.ArrayList<Edge<T>>();
}

Error: When program is executed, I enter string as a input when the addVertex(String) function is called and it gives an error String cannot be converted to Vertex. Error Recd From Java: java.lang.ClassCastException: java.lang.String cannot be converted to DG.Vertex

Can someone please explain me, what I am doing wrong. Thank you.

Please provide a better code sample. There is nothing here that shows the offending line of code calling addVertex() — HeavyE, Dec 10 '14 at 16:01
@HeavyE I have updated the code. So when my main function calls the addVertex(String), I get String to Vertex error. — user3337714, Dec 10 '14 at 19:23

HeavyE · Answer 1 · 2014-12-11T06:04:15.057

1

The problem is that you don't have a function addVertex(String).

Your function is addVertex(Vertex), so you need to create a new Vertex object and add that to the Graph. The key is that a vertex requires both a name and data.

Sample Code:

DirectedGraph<String> directedGraph = new DirectedGraph<String>();
// Create a vertex object with both a name and data
Vertex<String> sampleVertex = new Vertex<String>("name", "data"):
directedGraph.addVertex(sampleVertex);

If this still doesn't solve your problem, please post an example that includes the Edge class and the main method that is attempting to call addVertex().

edited Dec 11 '14 at 06:04

answered Dec 10 '14 at 21:54

HeavyE

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@Jared Burrows So How Will I be doing for the String? `DirectedGraph diGraph = new DirectedGraph();` `String vertexData = ?; // What is VertexData` `Vertex sample = new Vertex(data, vertexData);` `diGraph.addVertex(sample);` – user3337714 Dec 10 '14 at 23:13
@user3337714 I did not post the answer, only fix the formatting. – Jared Burrows Dec 11 '14 at 02:11

DirectedGraph: addVertex(Vertex v), String cannot be converted to Vertex

1 Answers1