LinkedListMultimap or MultiMap sequence

Question

I have the following multiMap:

1st: [3=>[4,5]]
2nd: [2=>[3]]
3rd: [0=>[2]]
4th: [5=>[1]]
5th: [4=>[1]]

I would like to get the sequence out of it such as:

0->2->3->[4,5]->1

Is it possible?

This is what I have tried, but doesn't seem to work correctly:

// the starting point is given from the start.

Collection<String> col = new HashSet<String>();
col.add("0");
buildPath2(myMultimap, col, result2);

static void buildPath2(Multimap<String, String> path, Collection<String> token, List<Collection<String>> result2) {
    if (token != null) {
        result2.add(token);
        Collection<String> c = null;
        for (String elem: token){
           c = path.get(elem);
        }
        buildPath2(path, c, result2);
    }
}

Answer 1

You've got two basic problems that you'll need to resolve.

1. Your program doesn't seem to output anything. Somewhere in there, you'll want to output result2 somehow.
2. After your for loop, c will be whatever you get from looking up the last element of token in the map. You probably wanted it to be a Set containing what you get from looking up all the elements of token in the map.

To deal with issue 2, you should probably change

Collection<String> c = null;
for (String elem: token){
   c = path.get(elem);
}

to

Collection<String> c = new HashSet<>();
for (String elem : token) {
    c.addAll(path.get(elem));
}