Method map

output/java8/1.4.13/MultiMap.java:36–43

(K key, V value)

public class MultiMap<K, V> extends LinkedHashMap<K,List<V>> {
    public void map(K key, V value) {
        List<V> elementsForKey = get(key);
        if ( elementsForKey==null ) {
            elementsForKey = new ArrayList<V>();
            super.put(key, elementsForKey);
        }
        elementsForKey.add(value);
    }
}