Creating a graph help!

Question

Hi,
I am having problems with the ideas of graphs
I think that an edge is a link and a node is the place where data is stored
i want the node to contain a string data value and a node id which is used to connect to another node
the problem is that the edge does not fit in the picture, that is worrying me. In many places they use edges for some reason
and I do not understand why. This is the code which i am up to.
Any comments if there is something i am missing?
public class graph
     private class Node
          String name;
          int nodeid;
          int to;
          int from;
          private static int nodeno=1;
          public Node()
               name=null;
               nodeid=nodeno;
               nodeno++;
               to=0;
               from=nodeid;
          public void LinkNode(Node a, Node b)
               a.to=b.nodeid;
}

Answer 1

When implementing an unweighted graph, you don't really need a Edge class. Here's how you could do it:
class Graph {
  Set<Node> nodes;
class Node {
  String name;
  int id;
  List<Node> edges; // a node can have zero or more edges (can be connected to 0 or more other Nodes)
But when your graph is weighted, you could define an Edge like this:
class Graph {
  Set<Node> nodes;
class Node {
  String name;
  int id;
  List<Edge> edges; // a node can have zero or more edges (can be connected to 0 or more other Nodes)
class Edge {
  double weight;
  Node destination;
}