Guava : LinkedHashMultimap values as list and not String

Question

I was reading about Guava's LinkedHashMultimap and thought it might be useful to me.

I have a requirement such that I have a map as follows:

Key:Value
A    B
A    C
A    D
P    Q
P    R

If above is the input in my map, then I want to use LinkedHashMultimap to create a map like:

Key : Value 
A     List<B,C,D>
P     List<Q,R>

Tried using LinkedHashMultimap but it has following issue:

    mapLen.entries().stream().forEach(entry -> {
        System.out.println("mapTemp2 key + " + entry.getKey());
        System.out.println("mapTemp2 value + " + entry.getValue());
    });

Above prints the String values in the map and not List<String>.

Can someone pointout how it can be done.

(Kindly note: I am aware of normal core java solution of iterating, checking and the creating list and inserting into map.)

Answer 1

As we can see in javadoc, Multimap#entries() returns Collection<Map.Entry<K,V>> - so basically, you iterate over each key/value pair, instead of key/(value set). To do so, try turning Multimap<K, V> to standard Map<K, List<V>>. You can do that with Multimap#asMap(), so your code would look like:

mapLen.asMap().entrySet().stream().forEach(entry -> {
    System.out.println("mapTemp2 key + " + entry.getKey());
    System.out.println("mapTemp2 value + " + entry.getValue());
});

PS. I guess you missed parenthesis after ...entries - it's a method, not a property, so you should have used:

//            vv DOWN HERE
mapLen.entries().stream().forEach(entry -> {
    System.out.println("mapTemp2 key + " + entry.getKey());
    System.out.println("mapTemp2 value + " + entry.getValue());
});