/guava/guava/src/com/google/common/collect/Sets.java
HashSet<E> set = newTreeSet( ) ;
HashSet<E> set = newHashSet ( ) ;
public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) { return (elements instanceof Collection) ? new HashSet<E>((Collection<? extends E>) elements) : newHashSet(elements.iterator()); } public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterator<? extends E> elements) { <extra_id_0> Iterators.addAll(set, elements); return set; } public static <E extends @Nullable Object> HashSet<E> newHashSetWithExpectedSize( int expectedSize) { return new HashSet<E>(Maps.capacity(expectedSize));