Dijksta的算法Java - 如何从对象的ArrayList中找到距离值最短的顶点

Question

我正在尝试用Java实现Dijkstra算法。我这样做是使用ArrayList，我知道还有其他数据结构可能更适合这个任务。但是，我想对ArrayLists感到满意，这就是我将要使用的内容。

我有一个对象的ArrayList。这些对象包含多个值，其中一个值是与源节点的距离。如何选择距离值最小的节点？

然后我想将具有最小距离值的顶点的名称设置为String＆＃34;最小的＆＃34;。

这是我到目前为止所拥有的。

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.ArrayList;

public class Graph
{

ArrayList<Vertex> vertexObjects = new ArrayList<Vertex>();
ArrayList<Edge> edgeObjects = new ArrayList<Edge>();
ArrayList<Vertex> visitedObjects = new ArrayList<Vertex>();
ArrayList<Vertex> unvisitedObjects = new ArrayList<Vertex>();
int numVertices = 0;

public void readFile()
{
    try {
        Scanner s = new Scanner(new File("graph.txt"));
        String sameVertex = "";

        while (s.hasNext()) {
            String preVertex = s.next();
            String postVertex = s.next();
            String distance = s.next();

            Edge temp = new Edge(preVertex, postVertex, distance);
            edgeObjects.add(temp);

            if (!(preVertex.equals(sameVertex)))
            {
                Vertex herp = new Vertex(preVertex, Double.POSITIVE_INFINITY, false, null);
                vertexObjects.add(herp);
                sameVertex = preVertex;
                numVertices++;
            }
        }
    } catch (FileNotFoundException e) {
        System.out.println("I can't find that file!");
    }
}

public void Dijkstra(String startVertex, String endVertex)
{
    // Change the distance of the startVertex to 0 and all others to infinity.
    for (int i = (numVertices-1); i >= 0; i--)
    {
        if (vertexObjects.get(i).vertexName.equals(startVertex))
        {
            vertexObjects.get(i).distance = 0;
        } else {
            vertexObjects.get(i).distance = Double.POSITIVE_INFINITY;
        }
        unvisitedObjects.add(vertexObjects.get(i));
    }
    String currentVertex = startVertex;
    //Set the node with lowest distance value to Current Status

    while( unvisitedObjects.size() != 0) {

            {
        //set current node to vertex with shortest distance

        string smallest;
        for (int j = (vertexObjects.size()-1); j >= 0; j++) {
            if (vertexObjects.get(j).distance < 0) {
                smallest = vertexObjects.get(j).distance;
            }

        }
    }

   }
}

public class Vertex
{
    public String vertexName;
    public double distance;
    public boolean visitedStatus;
    public String previousVertex;

public Vertex(String vertexName, double distance, boolean visitedStatus, String previousVertex)
{
    this.vertexName = vertexName;
    this.distance = distance;
    this.visitedStatus = visitedStatus;
    this.previousVertex = previousVertex;
}

public String toString()
{
    String d;
    if (this.visitedStatus = false) 
    {
        d = "unvisited";
    } else {
        d = "visited";
    }
    String s = "Vertex " + vertexName + " is " + d + "and is " + distance + " away from " + previousVertex + ".";
    return s;
}

}