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

public void testSpliterator_unsizedIterator() {
    String[] array = { "a", "b", "c", "d", "e", "f", "g", "h" };
    List<String> asList = Arrays.asList(array);
    ArrayList<String> expectedValues = new ArrayList<>(asList);

    Spliterator<String> sp = Spliterators.spliteratorUnknownSize(asList.iterator(), 0);
    SpliteratorTester.runBasicIterationTests(sp, expectedValues);

    sp = Spliterators.spliteratorUnknownSize(asList.iterator(), 0);
    SpliteratorTester.testSpliteratorNPE(sp);

    sp = Spliterators.spliteratorUnknownSize(asList.iterator(), 0);
    SpliteratorTester.runBasicSplitTests(sp, expectedValues, String::compareTo);

    // Assert the spliterator inherits any characteristics we ask it to.
    sp = Spliterators.spliterator(array, Spliterator.ORDERED);
    assertTrue(sp.hasCharacteristics(Spliterator.ORDERED));
}
 

@Test
public void testUnknownSize() {
    List<String> expected = IntStreamEx.range(200).mapToObj(x -> x + ":" + (x + 1)).toList();
    Supplier<Spliterator<String>> s = () -> new ZipSpliterator<>(Spliterators.spliteratorUnknownSize(IntStreamEx
            .range(200).iterator(), Spliterator.ORDERED), Spliterators.spliteratorUnknownSize(IntStreamEx.range(1,
        201).iterator(), Spliterator.ORDERED), (x, y) -> x + ":" + y, true);
    checkSpliterator("unknownSize", expected, s);
}
 

public static <T> Stream<T> adaptStream(Stream<T> stream, Function<? super T, ? extends DateTime> timestamp_fn, Duration stepsize) {
    if (stepsize.getMillis() <= 0L) return stream;

    final Iterator<T> iter = new SkippingIterator<>(stream.iterator(), timestamp_fn, stepsize);
    final Spliterator<T> spliter = Spliterators.spliteratorUnknownSize(iter, NONNULL | IMMUTABLE | ORDERED);
    return StreamSupport.stream(spliter, false);
}
 

/**
 * @return a {@link Stream} of unknown size with onClose attached to {@link Subscription#cancel()}
 */
public Stream<T> parallelStream() {
    BlockingIterable.SubscriberIterator<T> it = createIterator();
    source.subscribe(it);

    Spliterator<T> sp = Spliterators.spliteratorUnknownSize(it, 0);

    return StreamSupport.stream(sp, true).onClose(it);
}
 

/**
 * @return a {@link Stream} of unknown size with onClose attached to {@link Subscription#cancel()}
 */
public Stream<T> stream() {
    BlockingIterable.SubscriberIterator<T> it = createIterator();
    source.subscribe(it);

    Spliterator<T> sp = Spliterators.spliteratorUnknownSize(it, 0);

    return StreamSupport.stream(sp, false).onClose(it);
}
 

public Stream<City> parse(InputStream is) {
    Reader reader = new InputStreamReader(is);
    CSVReader csvReader = new CSVReader(reader);
    Iterator<City> iterator = new Iterator<City>() {
        private boolean isEndReached = false;
        
        @Override
        public boolean hasNext() {
            return !isEndReached;
        }

        @Override
        public City next() {
            try {
                String[] values = csvReader.readNext();
                if (values == null) {
                    isEndReached = true;
                    return null;
                } else {
                    return toCity(values);
                }
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }
    };
    Spliterator<City> spliterator = Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED);
    return StreamSupport.stream(spliterator, false).onClose(new Runnable() {
        @Override
        public void run() {
            IOUtils.closeQuietly(csvReader);
        }
    });
}
 

/**
 * Creates a new {@code ObservableSensor} using the specified 
 * {@link SensorParams}
 * 
 * @param params
 */
@SuppressWarnings("unchecked")
public ObservableSensor(SensorParams params) {
    if(!params.hasKey("ONSUB")) {
        throw new IllegalArgumentException("Passed improperly formed Tuple: no key for \"ONSUB\"");
    }
    
    this.params = params;
    
    Observable<String> obs = null;
    Object publisher = params.get("ONSUB");
    if(publisher instanceof Publisher) {
        obs = ((Publisher)publisher).observable();
    } else if(publisher instanceof Supplier<?>) {
        obs = ((Supplier<Publisher>)publisher).get().observable();
    } else {
        obs = (Observable<String>)publisher; 
    }
    
    Iterator<String> observerator = obs.toBlocking().getIterator();
    
    Iterator<String> iterator = new Iterator<String>() {
        @Override public boolean hasNext() { return observerator.hasNext(); }
        @Override public String next() {
            return observerator.next();
        }
    };
            
    int characteristics = Spliterator.SORTED | Spliterator.ORDERED;
    Spliterator<String> spliterator = Spliterators.spliteratorUnknownSize(iterator, characteristics);
  
    this.stream = BatchedCsvStream.batch(
        StreamSupport.stream(spliterator, false), BATCH_SIZE, DEFAULT_PARALLEL_MODE, HEADER_SIZE);
}
 

public static <TSource> Spliterator<TSource> spliterator(IEnumerable<TSource> source) {
    if (source == null)
        ThrowHelper.throwArgumentNullException(ExceptionArgument.source);

    if (source instanceof ICollection) {
        if (source instanceof IArray) {
            IArray<TSource> array = (IArray<TSource>) source;
            Object arr = array.getArray();
            Class<?> componentType = arr.getClass().getComponentType();
            if (componentType.isPrimitive()) {
                if (componentType == int.class)
                    //noinspection unchecked
                    return (Spliterator<TSource>) Spliterators.spliterator((int[]) arr, array._getStartIndex(), array._getEndIndex(), Spliterator.IMMUTABLE);
                if (componentType == long.class)
                    //noinspection unchecked
                    return (Spliterator<TSource>) Spliterators.spliterator((long[]) arr, array._getStartIndex(), array._getEndIndex(), Spliterator.IMMUTABLE);
                if (componentType == double.class)
                    //noinspection unchecked
                    return (Spliterator<TSource>) Spliterators.spliterator((double[]) arr, array._getStartIndex(), array._getEndIndex(), Spliterator.IMMUTABLE);
                return Spliterators.spliterator(array._toArray(), array._getStartIndex(), array._getEndIndex(), Spliterator.IMMUTABLE);
            }
            return Spliterators.spliterator((Object[]) arr, array._getStartIndex(), array._getEndIndex(), Spliterator.IMMUTABLE);
        }

        ICollection<TSource> collection = (ICollection<TSource>) source;
        return Spliterators.spliterator(collection.getCollection(), Spliterator.IMMUTABLE);
    }

    if (source instanceof IIListProvider) {
        IIListProvider<TSource> listProv = (IIListProvider<TSource>) source;
        int count = listProv._getCount(true);
        if (count != -1)
            return Spliterators.spliterator(source.enumerator(), count, Spliterator.IMMUTABLE);
    }

    return Spliterators.spliteratorUnknownSize(source.enumerator(), Spliterator.IMMUTABLE);
}
 

public Stream<JsonInput> asStream() {
  Spliterator<JsonInput> spliterator = Spliterators.spliteratorUnknownSize(
      this,
      ORDERED & IMMUTABLE);

  return StreamSupport.stream(spliterator, false);
}
 

@Override
public Spliterator<T> spliterator() {
    return Spliterators.spliteratorUnknownSize(iterator(), Spliterator.ORDERED);
}
 

public Spliterator<String> spliterator() {
    return Spliterators.spliteratorUnknownSize(list.iterator(), 0);
}
 

/**
 * Return a {@code Stream} that is lazily populated with {@code
 * Path} by searching for files in a file tree rooted at a given starting
 * file.
 *
 * <p> This method walks the file tree in exactly the manner specified by
 * the {@link #walk walk} method. For each file encountered, the given
 * {@link BiPredicate} is invoked with its {@link Path} and {@link
 * BasicFileAttributes}. The {@code Path} object is obtained as if by
 * {@link Path#resolve(Path) resolving} the relative path against {@code
 * start} and is only included in the returned {@link Stream} if
 * the {@code BiPredicate} returns true. Compare to calling {@link
 * java.util.stream.Stream#filter filter} on the {@code Stream}
 * returned by {@code walk} method, this method may be more efficient by
 * avoiding redundant retrieval of the {@code BasicFileAttributes}.
 *
 * <p> The returned stream contains references to one or more open directories.
 * The directories are closed by closing the stream.
 *
 * <p> If an {@link IOException} is thrown when accessing the directory
 * after returned from this method, it is wrapped in an {@link
 * UncheckedIOException} which will be thrown from the method that caused
 * the access to take place.
 *
 * @apiNote
 * This method must be used within a try-with-resources statement or similar
 * control structure to ensure that the stream's open directories are closed
 * promptly after the stream's operations have completed.
 *
 * @param   start
 *          the starting file
 * @param   maxDepth
 *          the maximum number of directory levels to search
 * @param   matcher
 *          the function used to decide whether a file should be included
 *          in the returned stream
 * @param   options
 *          options to configure the traversal
 *
 * @return  the {@link Stream} of {@link Path}
 *
 * @throws  IllegalArgumentException
 *          if the {@code maxDepth} parameter is negative
 * @throws  SecurityException
 *          If the security manager denies access to the starting file.
 *          In the case of the default provider, the {@link
 *          SecurityManager#checkRead(String) checkRead} method is invoked
 *          to check read access to the directory.
 * @throws  IOException
 *          if an I/O error is thrown when accessing the starting file.
 *
 * @see     #walk(Path, int, FileVisitOption...)
 * @since   1.8
 */
public static Stream<Path> find(Path start,
                                int maxDepth,
                                BiPredicate<Path, BasicFileAttributes> matcher,
                                FileVisitOption... options)
    throws IOException
{
    FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options);
    try {
        Spliterator<FileTreeWalker.Event> spliterator =
            Spliterators.spliteratorUnknownSize(iterator, Spliterator.DISTINCT);
        return StreamSupport.stream(spliterator, false)
                            .onClose(iterator::close)
                            .filter(entry -> matcher.test(entry.file(), entry.attributes()))
                            .map(entry -> entry.file());
    } catch (Error|RuntimeException e) {
        iterator.close();
        throw e;
    }
}
 

/**
 * Return a {@code Stream} that is lazily populated with {@code
 * Path} by searching for files in a file tree rooted at a given starting
 * file.
 *
 * <p> This method walks the file tree in exactly the manner specified by
 * the {@link #walk walk} method. For each file encountered, the given
 * {@link BiPredicate} is invoked with its {@link Path} and {@link
 * BasicFileAttributes}. The {@code Path} object is obtained as if by
 * {@link Path#resolve(Path) resolving} the relative path against {@code
 * start} and is only included in the returned {@link Stream} if
 * the {@code BiPredicate} returns true. Compare to calling {@link
 * java.util.stream.Stream#filter filter} on the {@code Stream}
 * returned by {@code walk} method, this method may be more efficient by
 * avoiding redundant retrieval of the {@code BasicFileAttributes}.
 *
 * <p> The returned stream contains references to one or more open directories.
 * The directories are closed by closing the stream.
 *
 * <p> If an {@link IOException} is thrown when accessing the directory
 * after returned from this method, it is wrapped in an {@link
 * UncheckedIOException} which will be thrown from the method that caused
 * the access to take place.
 *
 * @apiNote
 * This method must be used within a try-with-resources statement or similar
 * control structure to ensure that the stream's open directories are closed
 * promptly after the stream's operations have completed.
 *
 * @param   start
 *          the starting file
 * @param   maxDepth
 *          the maximum number of directory levels to search
 * @param   matcher
 *          the function used to decide whether a file should be included
 *          in the returned stream
 * @param   options
 *          options to configure the traversal
 *
 * @return  the {@link Stream} of {@link Path}
 *
 * @throws  IllegalArgumentException
 *          if the {@code maxDepth} parameter is negative
 * @throws  SecurityException
 *          If the security manager denies access to the starting file.
 *          In the case of the default provider, the {@link
 *          SecurityManager#checkRead(String) checkRead} method is invoked
 *          to check read access to the directory.
 * @throws  IOException
 *          if an I/O error is thrown when accessing the starting file.
 *
 * @see     #walk(Path, int, FileVisitOption...)
 * @since   1.8
 */
public static Stream<Path> find(Path start,
                                int maxDepth,
                                BiPredicate<Path, BasicFileAttributes> matcher,
                                FileVisitOption... options)
    throws IOException
{
    FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options);
    try {
        Spliterator<FileTreeWalker.Event> spliterator =
            Spliterators.spliteratorUnknownSize(iterator, Spliterator.DISTINCT);
        return StreamSupport.stream(spliterator, false)
                            .onClose(iterator::close)
                            .filter(entry -> matcher.test(entry.file(), entry.attributes()))
                            .map(entry -> entry.file());
    } catch (Error|RuntimeException e) {
        iterator.close();
        throw e;
    }
}
 

/**
 * Returns the script stack trace elements.
 * 
 * @param e
 *            the throwable object
 * @return the script stack trace elements
 */
public static Stream<StackTraceElement> stackTraceStream(Throwable e) {
    StackTraceElementIterator iterator = new StackTraceElementIterator(e);
    int characteristics = Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED;
    Spliterator<StackTraceElement> spliterator = Spliterators.spliteratorUnknownSize(iterator, characteristics);
    return StreamSupport.stream(spliterator, false).map(StackTraces::toScriptFrame);
}
 

/**
 * Creates a {@code Spliterator} without knowledge of collection size.
 *
 * @return a {@code Spliterator} over the elements in this collection.
 */
@Override
public Spliterator<E> spliterator() {
    return isSizeKnown() ? super.spliterator() : Spliterators.spliteratorUnknownSize(iterator(), 0);
}
 

/**
 * Creates a {@link Spliterator} over the elements described by this
 * {@code Iterable}.
 *
 * @implSpec
 * The default implementation creates an
 * <em><a href="../util/Spliterator.html#binding">early-binding</a></em>
 * spliterator from the iterable's {@code Iterator}.  The spliterator
 * inherits the <em>fail-fast</em> properties of the iterable's iterator.
 *
 * @implNote
 * The default implementation should usually be overridden.  The
 * spliterator returned by the default implementation has poor splitting
 * capabilities, is unsized, and does not report any spliterator
 * characteristics. Implementing classes can nearly always provide a
 * better implementation.
 *
 * @return a {@code Spliterator} over the elements described by this
 * {@code Iterable}.
 * @since 1.8
 */
default Spliterator<T> spliterator() {
    return Spliterators.spliteratorUnknownSize(iterator(), 0);
}
 

/**
 * Creates a {@link Spliterator} over the elements described by this
 * {@code Iterable}.
 *
 * @implSpec
 * The default implementation creates an
 * <em><a href="../util/Spliterator.html#binding">early-binding</a></em>
 * spliterator from the iterable's {@code Iterator}.  The spliterator
 * inherits the <em>fail-fast</em> properties of the iterable's iterator.
 *
 * @implNote
 * The default implementation should usually be overridden.  The
 * spliterator returned by the default implementation has poor splitting
 * capabilities, is unsized, and does not report any spliterator
 * characteristics. Implementing classes can nearly always provide a
 * better implementation.
 *
 * @return a {@code Spliterator} over the elements described by this
 * {@code Iterable}.
 * @since 1.8
 */
default Spliterator<T> spliterator() {
    return Spliterators.spliteratorUnknownSize(iterator(), 0);
}
 

/**
 * Creates a {@link Spliterator} over objects matching the query for which this {@link ResultSet} was constructed.
 *
 * @return a {@link Spliterator} over objects matching the query for which this {@link ResultSet} was constructed
 */
public Spliterator<O> spliterator() {
    return Spliterators.spliteratorUnknownSize(this.iterator(), Spliterator.ORDERED);
}
 

/**
 * Creates a {@link Spliterator} over the elements described by this
 * {@code Iterable}.
 *
 * @implSpec
 * The default implementation creates an
 * <em><a href="Spliterator.html#binding">early-binding</a></em>
 * spliterator from the iterable's {@code Iterator}.  The spliterator
 * inherits the <em>fail-fast</em> properties of the iterable's iterator.
 *
 * @implNote
 * The default implementation should usually be overridden.  The
 * spliterator returned by the default implementation has poor splitting
 * capabilities, is unsized, and does not report any spliterator
 * characteristics. Implementing classes can nearly always provide a
 * better implementation.
 *
 * @return a {@code Spliterator} over the elements described by this
 * {@code Iterable}.
 * @since 1.8
 */
default Spliterator<T> spliterator() {
    return Spliterators.spliteratorUnknownSize(iterator(), 0);
}
 

/**
 * Creates a {@link Spliterator} over the elements described by this
 * {@code Iterable}.
 *
 * @implSpec
 * The default implementation creates an
 * <em><a href="Spliterator.html#binding">early-binding</a></em>
 * spliterator from the iterable's {@code Iterator}.  The spliterator
 * inherits the <em>fail-fast</em> properties of the iterable's iterator.
 *
 * @implNote
 * The default implementation should usually be overridden.  The
 * spliterator returned by the default implementation has poor splitting
 * capabilities, is unsized, and does not report any spliterator
 * characteristics. Implementing classes can nearly always provide a
 * better implementation.
 *
 * @return a {@code Spliterator} over the elements described by this
 * {@code Iterable}.
 * @since 1.8
 */
default Spliterator<T> spliterator() {
    return Spliterators.spliteratorUnknownSize(iterator(), 0);
}