实现图-Java

Question

The objective of this program to implement a graph in JAVA without using any libraries. This is not a homework assignment, just some practice. I am trying to implement a unidirected weighted graph which can be later passed in as a parameter to a Kruskal's or a Prim's algorithm to implement Minimum Spanning Tree. Since I am new to datastructures, I am having a hard time to figure how to go about implementing a graph. Adjacency Matrix/List is something I would want to avoid, can I go forward with the following approach:

/**
 * Graph.java: This is the main file.
 */ 
public class Graph {

    public static void main(String[] args)
    {
        Node n1 = new Node("A");
        Node n2 = new Node("B");
        Node n3 = new Node("C");
        Node n4 = new Node("D");
        Node n5 = new Node("E");
        Node n6 = new Node("F");

        Edges e1 = new Edges(n1, n2, 5);
        Edges e2 = new Edges(n1, n3, 3);
        Edges e3 = new Edges(n2, n4, 5);
        Edges e4 = new Edges(n2, n5, 2);
        Edges e5 = new Edges(n3, n6, 7);
    }
}


/**
 * Node.java class used to represent vertices
 */
public class Node {
    private String name;
    public Node(String name)
    {
        this.name = name;
    }
}

/**
 * Edges.java class used to represent edges.
 */
public class Edges {
    private int weight;
    private Node sNode;
    private Node dNode;
    public Edges(Node sNode, Node dNode, int weight)
    {
        this.sNode = sNode;
        this.dNode = dNode;
        this.weight = weight;
    }
}

Answer 1

Personally I would keep the edges attached to the nodes. I realize it doubles the number of edges (because they are bidirectional in your case) but it makes traversing nodes a lot faster because you don't have to iterate through your edges to find where you can go next. I realize you mentioned you're not interested in adjacency lists but it seems like a better approach in most cases in terms of performance, although I'm sure you have your reasons. So I'm posting the code anyway, just so it's there for others.

(no get/set on purpose to keep the code succinct)

public class Node {
    private String name;
    private List<Edge> neighbors;

    public Node(String name) {
        this.name = name;
    }

    public void AddUndirectedEdge(Node destination, int weight) {
        neighbors.Add(new Edge(destination, weight));
        destination.neighbors.Add(new Edge(this, weight));
    }

    private static class Edge {
        public Node destination;
        public int weight;

        public Edge(Node destination, int weight) {
            this.destination = destination;
            this.weight = weight;
        }
    }
}