import java.util.Set;import com.google.common.collect.HashMultimap;import com.google.common.collect.SetMultimap;public class ManyToMany<K, V> { private final SetMultimap<K, V> keysToValues = HashMultimap.create(); private final SetMultimap<V, K> valuesToKeys = HashMultimap.create(); public Set<V> getValues(K key) { return keysToValues.get(key); } public Set<K> getKeys(V value) { return valuesToKeys.get(value); } public boolean put(K key, V value) { return keysToValues.put(key, value) && valuesToKeys.put(value, key); } public boolean putAll(K key, Iterable<? extends V> values) { boolean changed = false; for (V value : values) { changed |= put(key, value); } return changed; }}
