Java Stream.onClose方法代码示例

import java.util.stream.Stream; //导入方法依赖的package包/类
@SafeVarargs
private static <T> Stream<T> withCloseHandler(Stream<T> stream, Iterator<T>... iterators) {
    return stream.onClose(() -> {
        for (Iterator<T> iterator : iterators) {
            if (iterator instanceof AutoCloseable) {
                try {
                    ((AutoCloseable) iterator).close();
                } catch (Exception ex) {
                    throw new MemgraphException(
                            String.format("exception occurred when closing %s", iterator.getClass().getName()),
                            ex
                    );
                }
            }
        }
    });
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
@Test public void testZip_close() {
  Stream<?> left = Stream.of("a");
  Stream<?> right = Stream.of(1);
  AtomicBoolean leftClosed = new AtomicBoolean();
  AtomicBoolean rightClosed = new AtomicBoolean();
  left.onClose(() -> leftClosed.set(true));
  right.onClose(() -> rightClosed.set(true));
  try (BiStream<?, ?> stream = BiStream.zip(left, right)) {}
  assertThat(leftClosed.get()).isTrue();
  assertThat(rightClosed.get()).isTrue();
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
@Test public void testIndexed_close() {
  Stream<?> stream = Stream.of("a");
  AtomicBoolean closed = new AtomicBoolean();
  stream.onClose(() -> closed.set(true));
  try (BiStream<?, ?> indexed = BiStream.indexed(stream).distinct()) {}
  assertThat(closed.get()).isTrue();
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
@Test public void close() {
  Stream<?> stream = kind.natural(0);
  AtomicBoolean closed = new AtomicBoolean();
  stream.onClose(() -> closed.set(true));
  try (Stream<?> diced = MoreStreams.dice(stream, 1)) {}
  assertThat(closed.get()).isTrue();
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
/**
 * Turn a query results {@link Iterable} into a {@link Stream}.
 * @param <T> Results type
 * @param queryResultsIterable Iterable to convert (not null)
 * @param closeHandler Optional close handler to perform closing operations when Stream is closed
 * @return Stream from Iterable
 */
public static <T> Stream<T> asResultsStream(Iterable<T> queryResultsIterable, Runnable closeHandler) {
	ObjectUtils.argumentNotNull(queryResultsIterable, "Iterable must be not null");
	Stream<T> stream = StreamSupport.stream(queryResultsIterable.spliterator(), false);
	if (closeHandler != null) {
		stream.onClose(closeHandler);
	}
	return stream;
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
/**
 * Dices {@code stream} into smaller chunks each with up to {@code maxSize} elements.
 *
 * <p>For a sequential stream, the first N-1 chunk's will contain exactly {@code maxSize}
 * elements and the last chunk may contain less (but never 0).
 * However for parallel streams, it's possible that the stream is split in roughly equal-sized
 * sub streams before being diced into smaller chunks, which then will result in more than one
 * chunks with less than {@code maxSize} elements.
 *
 * <p>This is an <a href="https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html#StreamOps">
 * intermediary operation</a>.
 *
 * @param stream the source stream to be diced
 * @param maxSize the maximum size for each chunk
 * @return Stream of diced chunks each being a list of size up to {@code maxSize}
 * @throws IllegalStateException if {@code maxSize <= 0}
 */
public static <T> Stream<List<T>> dice(Stream<? extends T> stream, int maxSize) {
  requireNonNull(stream);
  if (maxSize <= 0) throw new IllegalArgumentException();
  Stream<List<T>> diced = StreamSupport.stream(
      () -> dice(stream.spliterator(), maxSize), Spliterator.NONNULL, stream.isParallel());
  return diced.onClose(stream::close);
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
/**
 * Returns a stream of match results from this scanner. The stream
 * contains the same results in the same order that would be returned by
 * calling {@code findWithinHorizon(pattern, 0)} and then {@link #match}
 * successively as long as {@link #findWithinHorizon findWithinHorizon()}
 * finds matches.
 *
 * <p>The resulting stream is sequential and ordered. All stream elements are
 * non-null.
 *
 * <p>Scanning starts upon initiation of the terminal stream operation, using the
 * current state of this scanner. Subsequent calls to any methods on this scanner
 * other than {@link #close} and {@link #ioException} may return undefined results
 * or may cause undefined effects on the returned stream. The returned stream's source
 * {@code Spliterator} is <em>fail-fast</em> and will, on a best-effort basis, throw a
 * {@link java.util.ConcurrentModificationException} if any such calls are detected
 * during stream pipeline execution.
 *
 * <p>After stream pipeline execution completes, this scanner is left in an indeterminate
 * state and cannot be reused.
 *
 * <p>If this scanner contains a resource that must be released, this scanner
 * should be closed, either by calling its {@link #close} method, or by
 * closing the returned stream. Closing the stream will close the underlying scanner.
 * {@code IllegalStateException} is thrown if the scanner has been closed when this
 * method is called, or if this scanner is closed during stream pipeline execution.
 *
 * <p>As with the {@link #findWithinHorizon findWithinHorizon()} methods, this method
 * might block waiting for additional input, and it might buffer an unbounded amount of
 * input searching for a match.
 *
 * @apiNote
 * For example, the following code will read a file and return a list
 * of all sequences of characters consisting of seven or more Latin capital
 * letters:
 *
 * <pre>{@code
 * try (Scanner sc = new Scanner(Paths.get("input.txt"))) {
 *     Pattern pat = Pattern.compile("[A-Z]{7,}");
 *     List<String> capWords = sc.findAll(pat)
 *                               .map(MatchResult::group)
 *                               .collect(Collectors.toList());
 * }
 * }</pre>
 *
 * @param pattern the pattern to be matched
 * @return a sequential stream of match results
 * @throws NullPointerException if pattern is null
 * @throws IllegalStateException if this scanner is closed
 * @since 9
 */
public Stream<MatchResult> findAll(Pattern pattern) {
    Objects.requireNonNull(pattern);
    ensureOpen();
    Stream<MatchResult> stream = StreamSupport.stream(new FindSpliterator(pattern), false);
    return stream.onClose(this::close);
}
 

import java.util.stream.Stream; //导入方法依赖的package包/类
/**
 * Returns a stream of delimiter-separated tokens from this scanner. The
 * stream contains the same tokens that would be returned, starting from
 * this scanner's current state, by calling the {@link #next} method
 * repeatedly until the {@link #hasNext} method returns false.
 *
 * <p>The resulting stream is sequential and ordered. All stream elements are
 * non-null.
 *
 * <p>Scanning starts upon initiation of the terminal stream operation, using the
 * current state of this scanner. Subsequent calls to any methods on this scanner
 * other than {@link #close} and {@link #ioException} may return undefined results
 * or may cause undefined effects on the returned stream. The returned stream's source
 * {@code Spliterator} is <em>fail-fast</em> and will, on a best-effort basis, throw a
 * {@link java.util.ConcurrentModificationException} if any such calls are detected
 * during stream pipeline execution.
 *
 * <p>After stream pipeline execution completes, this scanner is left in an indeterminate
 * state and cannot be reused.
 *
 * <p>If this scanner contains a resource that must be released, this scanner
 * should be closed, either by calling its {@link #close} method, or by
 * closing the returned stream. Closing the stream will close the underlying scanner.
 * {@code IllegalStateException} is thrown if the scanner has been closed when this
 * method is called, or if this scanner is closed during stream pipeline execution.
 *
 * <p>This method might block waiting for more input.
 *
 * @apiNote
 * For example, the following code will create a list of
 * comma-delimited tokens from a string:
 *
 * <pre>{@code
 * List<String> result = new Scanner("abc,def,,ghi")
 *     .useDelimiter(",")
 *     .tokens()
 *     .collect(Collectors.toList());
 * }</pre>
 *
 * <p>The resulting list would contain {@code "abc"}, {@code "def"},
 * the empty string, and {@code "ghi"}.
 *
 * @return a sequential stream of token strings
 * @throws IllegalStateException if this scanner is closed
 * @since 9
 */
public Stream<String> tokens() {
    ensureOpen();
    Stream<String> stream = StreamSupport.stream(new TokenSpliterator(), false);
    return stream.onClose(this::close);
}