Method filter

output/java_guava/1.4.19/Multisets.java:288–298

Returns a view of the elements of unfiltered that satisfy a predicate. The returned multiset is a live view of unfiltered; changes to one affect the other. The resulting multiset's iterators, and those of its entrySet() and elementSet(), do not support {@code remo

(Multiset<E> unfiltered, Predicate<? super E> predicate)

   */

  @Beta
  public static <E> Multiset<E> filter(Multiset<E> unfiltered, Predicate<? super E> predicate) {
    if (unfiltered instanceof FilteredMultiset) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.
      FilteredMultiset<E> filtered = (FilteredMultiset<E>) unfiltered;
      Predicate<E> combinedPredicate = Predicates.<E>and(filtered.predicate, predicate);
      return new FilteredMultiset<E>(filtered.unfiltered, combinedPredicate);
    }
    return new FilteredMultiset<E>(unfiltered, predicate);
  }

  private static final class FilteredMultiset<E> extends AbstractMultiset<E> {
    final Multiset<E> unfiltered;