java.util.Spliterators#emptySpliterator ( )源码实例Demo

/**
 * Fetch data immediately before traversing or sub-page splitting.
 */
private Spliterator<T> ensurePage() {
    if (danglingFirstPage != null) {
        final Spliterator<T> fp = danglingFirstPage;
        danglingFirstPage = null;
        currentPage = fp;
        start = fp.getExactSizeIfKnown();
        return fp;
    } else if (currentPage != null) {
        return currentPage;
    } else if (start >= end) {
        return Spliterators.emptySpliterator();
    }
    var spliterator = spliterator(supplier.fetch(start, min(end - start, pageSize), l -> end = min(l, end)));
    start += spliterator.getExactSizeIfKnown();
    currentPage = spliterator;
    return spliterator;
}
 

private boolean init() {
    if (context == null)
        return false;
    if (target == null) {
        Box<T> first = new Box<>();
        source = TailSpliterator.tryAdvanceWithTail(source, first);
        Stream<U> stream = source == null ? emptyMapper.get() : mapper.apply(first.a, StreamEx.of(source));
        source = null;
        mapper = null;
        emptyMapper = null;
        if (stream == null) {
            target = Spliterators.emptySpliterator();
        } else {
            StreamContext ctx = StreamContext.of(stream);
            if (ctx.closeHandler != null)
                context.onClose(ctx.closeHandler);
            target = stream.spliterator();
        }
    }
    return true;
}
 

public static <T> Spliterator<T> dropRight(Spliterator<T> source, int skip){

        if(skip==0){
            return source;
        }
        if(skip==source.getExactSizeIfKnown()){ //right sized already
            return Spliterators.emptySpliterator();
        }

        return new SkipLastSpliterator<T>(source,skip);
    }
 

@Override
public Spliterator<T> trySplit() {
    Spliterator<T> source = this.source;
    switch (ThreadLocalRandom.current().nextInt(3)) {
    case 0:
        return Spliterators.emptySpliterator();
    case 1:
        this.source = Spliterators.emptySpliterator();
        return source;
    default:
        Spliterator<T> split = source.trySplit();
        return split == null ? null : new EmptyingSpliterator<>(split);
    }
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<Object> spliterator() {
	return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<Object> spliterator() {
	return Spliterators.emptySpliterator();
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Returns a {@code StreamEx} consisting of the distinct elements (according
 * to {@link Object#equals(Object)}) which appear at least specified number
 * of times in this stream.
 *
 * <p>
 * This operation is not guaranteed to be stable: any of equal elements can
 * be selected for the output. However if this stream is ordered then order
 * is preserved.
 *
 * <p>
 * This is a stateful <a
 * href="package-summary.html#StreamOps">quasi-intermediate</a> operation.
 *
 * @param atLeast minimal number of occurrences required to select the
 *        element. If atLeast is 1 or less, then this method is equivalent
 *        to {@link #distinct()}.
 * @return the new stream
 * @see #distinct()
 * @since 0.3.1
 */
public S distinct(long atLeast) {
    if (atLeast <= 1)
        return distinct();
    Spliterator<T> spliterator = spliterator();
    Spliterator<T> result;
    if (spliterator.hasCharacteristics(Spliterator.DISTINCT))
        // already distinct: cannot have any repeating elements
        result = Spliterators.emptySpliterator();
    else
        result = new DistinctSpliterator<>(spliterator, atLeast);
    return supply(result);
}
 

/**
 * Returns an empty spliterator in which calls to
 * {@link java.util.Spliterator#trySplit()} always return {@code null}.
 *
 * @return an empty spliterator
 * @since 1.8
 */
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Returns an empty spliterator in which calls to
 * {@link java.util.Spliterator#trySplit()} always return {@code null}.
 *
 * @return an empty spliterator
 * @since 1.8
 */
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Returns an empty spliterator in which calls to
 * {@link java.util.Spliterator#trySplit()} always return {@code null}.
 *
 * @return an empty spliterator
 * @since 1.8
 */
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Returns an empty spliterator in which calls to
 * {@link java.util.Spliterator#trySplit()} always return {@code null}.
 *
 * @return an empty spliterator
 * @since 1.8
 */
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Returns an empty spliterator in which calls to
 * {@link java.util.Spliterator#trySplit()} always return {@code null}.
 *
 * @return an empty spliterator
 * @since 1.8
 */
public Spliterator<E> spliterator() {
    return Spliterators.emptySpliterator();
}
 

/**
 * Performs a cross product of current stream with specified
 * {@link Collection} of elements. As a result the {@link EntryStream} is
 * created whose keys are elements of current stream and values are elements
 * of the specified collection.
 * 
 * <p>
 * The resulting stream contains all the possible combinations of keys and
 * values.
 * 
 * <p>
 * This is an <a href="package-summary.html#StreamOps">intermediate</a>
 * operation.
 * 
 * @param <V> the type of collection elements
 * @param other the collection to perform a cross product with
 * @return the new {@code EntryStream}
 * @throws NullPointerException if other is null
 * @since 0.2.3
 */
public <V> EntryStream<T, V> cross(Collection<? extends V> other) {
    if (other.isEmpty())
        return new EntryStream<>(Spliterators.emptySpliterator(), context);
    return cross(t -> of(other));
}