java - Shortest path (fewest nodes) for unweighted graph

Question

I'm trying build a method which returns the shortest path from one node to another in an unweighted graph. I considered the use of Dijkstra's but this seems a bit overkill since I only want one pair. Instead I have implemented a breadth-first search, but the trouble is that my returning list contains some of the nodes that I don't want - how can I modify my code to achieve my goal?

public List<Node> getDirections(Node start, Node finish){
    List<Node> directions = new LinkedList<Node>();
    Queue<Node> q = new LinkedList<Node>();
    Node current = start;
    q.add(current);
    while(!q.isEmpty()){
        current = q.remove();
        directions.add(current);
        if (current.equals(finish)){
            break;
        }else{
            for(Node node : current.getOutNodes()){
                if(!q.contains(node)){
                    q.add(node);
                }
            }
        }
    }
    if (!current.equals(finish)){
        System.out.println("can't reach destination");
    }
    return directions;
}

Answer 1

Actually your code will not finish in cyclic graphs, consider graph 1 -> 2 -> 1. You must have some array where you can flag which node's you've visited already. And also for each node you can save previous nodes, from which you came. So here is correct code:

private Map<Node, Boolean>> vis = new HashMap<Node, Boolean>();

private Map<Node, Node> prev = new HashMap<Node, Node>();

public List getDirections(Node start, Node finish){
    List directions = new LinkedList();
    Queue q = new LinkedList();
    Node current = start;
    q.add(current);
    vis.put(current, true);
    while(!q.isEmpty()){
        current = q.remove();
        if (current.equals(finish)){
            break;
        }else{
            for(Node node : current.getOutNodes()){
                if(!vis.contains(node)){
                    q.add(node);
                    vis.put(node, true);
                    prev.put(node, current);
                }
            }
        }
    }
    if (!current.equals(finish)){
        System.out.println("can't reach destination");
    }
    for(Node node = finish; node != null; node = prev.get(node)) {
        directions.add(node);
    }
    directions.reverse();
    return directions;
}