Cant figure out whats wrong with my strategy design pattern

Question

I am using a strategy design pattern for my software engineering course but I am unsure what is wrong with it. The syntax errors I am getting saying 'Duplicate method getPath() in Route' and 'Syntax error on token public, class expected after' and 'return type missing' but i do have return.

package wpi.cs509.routeFinder;

import wpi.cs509.dataModel.*;
import wpi.cs509.dataManager.*;
import wpi.cs509.routeFinder.*;

import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.PriorityQueue;

public interface Route {
   public ArrayList<Point> getPath();
}

public DikstraRoute implements Route {
   public DikstraRoute(Point start, Graph g, Point destination) {
        if(source.getId()==destination.getId()){
            ArrayList<Point> point=new ArrayList<Point>();
            point.add(source);
            return point;
        }

        source.minDistance = 0;
        PriorityQueue<Point> pointQueue = new PriorityQueue<Point>();
        pointQueue.add(source);

    while (!pointQueue.isEmpty()) {
        Point u = pointQueue.poll();

            // Visit each edge exiting u
            for (Edge e : g.getNeighbors(u))
            {
                try
                {

                Point v = g.getPointById(e.getePointId()!=u.getId()?e.getePointId():e.getsPointId());

                float weight = e.getWeight();
                double distanceThroughU = u.minDistance + weight;
        if (distanceThroughU < v.minDistance) {
            pointQueue.remove(v);
            v.minDistance = distanceThroughU ;
            v.previous = u;
            pointQueue.add(v);
  //  System.out.println("u.id is"+u.getId());
                }
                }catch(NullPointerException e1)
                {
            System.out.println(e.getId()+"**********"+u.getName());
                }
            }
        }
   }

   @Override
   public ArrayList<Point> getPath() {
        ArrayList<Point> path = new ArrayList<Point>();
        for (Point vertex = destination; vertex != null; vertex = vertex.previous){
            path.add(vertex);
        }

        Collections.reverse(path);
        return path;
   }
}

public PrimsRoute implements Route {
       public PrimsRoute(Point start, Graph g, Point destination) {
        if(source.getId()==destination.getId()){
            ArrayList<Point> point=new ArrayList<Point>();
            point.add(source);
            return point;
        }

        source.minDistance = 0;
        pointQueue.insert(source, source.minDistance);
        while (!pointQueue.isEmpty()) {
            int v = pointQueue.remove();
            scan(Graph G, v);
        }
   }

    @Override
    public ArrayList<Point> getPath() {
        ArrayList<Point> path = new ArrayList<Point>();
        for (Point vertex = destination; vertex != null; vertex = vertex.previous){
            path.add(vertex);
        }

        Collections.reverse(path);
        return path;
   }
}

What do you think this declaration `public PrimsRoute implements Route` should do? Why do you think so? Voting to close as typo. — Sotirios Delimanolis, Dec 15 '15 at 15:13

score -1 · Answer 1 · answered Dec 15 '15 at 15:18

-1

You've missed the keyword class in your class declarations. Just like you declared Route as an interface you have to declare DikstraRoute and PrimsRoute as classes. For example:

public class DikstraRoute implements Route {
    ...
}

answered Dec 15 '15 at 15:18

E-Riz

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Cant figure out whats wrong with my strategy design pattern

1 Answers1