将文件中的输入转换为 object 参考

Question

What I'm wondering is, is there a way to read the file so that the strings 'vertex' and 'connected' can be cast as a reference to the Vertex objects outside the loop? The Strings will share the same name as the file is read, with it progressing from at, so that isn't a problem. If this isn't possible, is there any other way to work around this? Maybe by somehow creating a vertex object within the loop yet not overwriting it? I tried it but it would overwrite itself for each loop, as it would create a new Vertex with the same value each time. Thanks in advance.

    public static void main(String[] args) throws FileNotFoundException {

    File file = new File("ass3.txt");

    Scanner scan = new Scanner(f);

    if (file.exists() == false) {
        System.out.println("File doesn't exist or could not be found.");
        System.exit(0);
    }

    int nVertices = scan.nextInt();
    int nEdges = scan.nextInt();

    for (int i = 0; i < 21; i++) {
        String s = scan.nextLine();
    }

    Queue selectedSet = new Queue();
    Queue candidateSet = new Queue();

    Vertex a = new Vertex("a");
    Vertex b = new Vertex("b");
    Vertex c = new Vertex("c");
    Vertex d = new Vertex("d");
    Vertex e = new Vertex("e");
    Vertex f = new Vertex("f");
    Vertex g = new Vertex("g");
    Vertex h = new Vertex("h");
    Vertex i = new Vertex("i");
    Vertex j = new Vertex("j");
    Vertex k = new Vertex("k");
    Vertex l = new Vertex("l");
    Vertex m = new Vertex("m");
    Vertex n = new Vertex("n");
    Vertex o = new Vertex("o");
    Vertex p = new Vertex("p");
    Vertex q = new Vertex("q");
    Vertex r = new Vertex("r");
    Vertex s = new Vertex("s");
    Vertex t = new Vertex("t");

    for (int z = 0; z < 99; z++) {

        String vertex = scan.next();
        String connected = scan.next();
        int weight = scan.nextInt();

        vertex.addNeighbour(new Edge(weight,vertex,connected));
    }

Answer 1

You should be using a Map . This maps objects->objects, so in this case we would want it to be Strings->Vertex.

Some sample code:

HashMap<String, Vertex> vertices = new HashMap<String, Vertex>();
vertices.put("a", new Vertex("a"));
...

You can then reference the map in or outside your loop

Vertex v = vertices.get(vertex);