How to iterate over MultivaluedMap using forEach and a lambda expression

Question

Java 8 allows iteration over a Map using forEach and a lambda expression as follows:

myMap.forEach((k, v)->{ System.out.println("Key: " + k + " Value: " + v); });

Is it possible to iterate over a MultivaluedMap using forEach and a lambda expression?

UDPATE

How do I call foo with 2 String parameters for a MultivaluedMap<String, String>?

myMultiMap.forEach((k, v)->{ foo(k, v); });

Answer 1

The interface MultivaluedMap<K, V> extends the Map<K,List<V>> interface, therefore, there is forEach method and that is possible to use it.

new MultivaluedHashMap<String, String>()
        .forEach((String key, List<String> list)-> { ... });

I don't know what your foo method does, but I suggest* considering my point about that:

public <K, V> void foo(K key, V... values) { ... }

In such case, you needn't write inner forEach inside the lambda.
*(it is wrong as explained @Holder in the comments)

So, there is the only one proper way:

map.forEach((k, l) -> l.forEach( v -> foo(k, v)));