PathFinder .java in a programe

PathFinder.java

public class PathFinder

 {

 private ST  prev = new ST();

    private ST dist = new ST();

    public PathFinder(Graph G, String s)

       {

                   Queue q = new Queue();

        q.enqueue(s);

        dist.put(s, 0);

       

        while (!q.isEmpty())

           {

            String v = q.dequeue();

            for (String w : G.adjacentTo(v))

            {

                if (!dist.contains(w))

            {

                    q.enqueue(w);

                    dist.put(w, 1 + dist.get(v));

                    prev.put(w, v);

                }

            }

        }

    }

    public boolean isReachable(String v)

    {

        return dist.contains(v);

    }

    public int distanceTo(String v)

    {

        if (!dist.contains(v)) return Integer.MAX_VALUE;

        return dist.get(v);

    }

                public Iterable pathTo(String v)

       {

        Stack path = new Stack();

        while (v != null && dist.contains(v))

       {

            path.push(v);

            v = prev.get(v);

        }

        return path;

    }

               public static void main(String[] args)

               {

        String filename  = args[0];

        String delimiter = args[1];

        In in = new In(filename);

        Graph G = GraphGenerator.read(in, delimiter);

        String s = args[2];

        PathFinder pf = new PathFinder(G, s);

        while (!StdIn.isEmpty()) {

            String t = StdIn.readLine();

            for (String v : pf.pathTo(t))

           {

                StdOut.println("   " + v);

            }

            StdOut.println("distance " + pf.distanceTo(t));

        }

    }

            }