Java Code Examples for java.util.Collections#emptyIterator()

The following examples show how to use java.util.Collections#emptyIterator() . These examples are extracted from open source projects. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. You may check out the related API usage on the sidebar.
Example 1
Source Project: Bytecoder   File: ImageIO.java    License: Apache License 2.0 6 votes vote down vote up
/**
 * Returns an {@code Iterator} containing all currently
 * registered {@code ImageTranscoder}s that claim to be
 * able to transcode between the metadata of the given
 * {@code ImageReader} and {@code ImageWriter}.
 *
 * @param reader an {@code ImageReader}.
 * @param writer an {@code ImageWriter}.
 *
 * @return an {@code Iterator} containing
 * {@code ImageTranscoder}s.
 *
 * @exception IllegalArgumentException if {@code reader} or
 * {@code writer} is {@code null}.
 */
public static Iterator<ImageTranscoder>
    getImageTranscoders(ImageReader reader, ImageWriter writer)
{
    if (reader == null) {
        throw new IllegalArgumentException("reader == null!");
    }
    if (writer == null) {
        throw new IllegalArgumentException("writer == null!");
    }
    ImageReaderSpi readerSpi = reader.getOriginatingProvider();
    ImageWriterSpi writerSpi = writer.getOriginatingProvider();
    ServiceRegistry.Filter filter =
        new TranscoderFilter(readerSpi, writerSpi);

    Iterator<ImageTranscoderSpi> iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageTranscoderSpi.class,
                                        filter, true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageTranscoderIterator(iter);
}
 
Example 2
/**
 * Returns an <code>Iterator</code> containing all currently
 * registered <code>ImageWriter</code>s that claim to be able to
 * encode the named format.
 *
 * @param formatName a <code>String</code> containing the informal
 * name of a format (<i>e.g.</i>, "jpeg" or "tiff".
 *
 * @return an <code>Iterator</code> containing
 * <code>ImageWriter</code>s.
 *
 * @exception IllegalArgumentException if <code>formatName</code> is
 * <code>null</code>.
 *
 * @see javax.imageio.spi.ImageWriterSpi#getFormatNames
 */
public static Iterator<ImageWriter>
    getImageWritersByFormatName(String formatName)
{
    if (formatName == null) {
        throw new IllegalArgumentException("formatName == null!");
    }
    Iterator iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
                                new ContainsFilter(writerFormatNamesMethod,
                                                   formatName),
                                        true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageWriterIterator(iter);
}
 
Example 3
Source Project: JDKSourceCode1.8   File: ImageIO.java    License: MIT License 6 votes vote down vote up
/**
 * Returns an <code>Iterator</code> containing all currently
 * registered <code>ImageWriter</code>s that claim to be able to
 * encode the named format.
 *
 * @param formatName a <code>String</code> containing the informal
 * name of a format (<i>e.g.</i>, "jpeg" or "tiff".
 *
 * @return an <code>Iterator</code> containing
 * <code>ImageWriter</code>s.
 *
 * @exception IllegalArgumentException if <code>formatName</code> is
 * <code>null</code>.
 *
 * @see javax.imageio.spi.ImageWriterSpi#getFormatNames
 */
public static Iterator<ImageWriter>
    getImageWritersByFormatName(String formatName)
{
    if (formatName == null) {
        throw new IllegalArgumentException("formatName == null!");
    }
    Iterator iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
                                new ContainsFilter(writerFormatNamesMethod,
                                                   formatName),
                                        true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageWriterIterator(iter);
}
 
Example 4
/**
 * Returns an iterator over property values used in the {@code for each...in} statement. Aside from built-in JS
 * objects, it also operates on Java arrays, any {@link Iterable}, as well as on {@link Map} objects, iterating over
 * map values.
 * @param obj object to iterate on.
 * @return iterator over the object's property values.
 */
public static Iterator<?> toValueIterator(final Object obj) {
    if (obj instanceof ScriptObject) {
        return ((ScriptObject)obj).valueIterator();
    }

    if (obj instanceof JSObject) {
        return ((JSObject)obj).values().iterator();
    }

    final Iterator<?> itr = iteratorForJavaArrayOrList(obj);
    if (itr != null) {
        return itr;
    }

    if (obj instanceof Map) {
        return ((Map<?,?>)obj).values().iterator();
    }

    final Object wrapped = Global.instance().wrapAsObject(obj);
    if (wrapped instanceof ScriptObject) {
        return ((ScriptObject)wrapped).valueIterator();
    }

    return Collections.emptyIterator();
}
 
Example 5
Source Project: hottub   File: ImageIO.java    License: GNU General Public License v2.0 6 votes vote down vote up
/**
 * Returns an <code>Iterator</code> containing all currently
 * registered <code>ImageWriter</code>s that claim to be able to
 * encode files with the given suffix.
 *
 * @param fileSuffix a <code>String</code> containing a file
 * suffix (<i>e.g.</i>, "jpg" or "tiff").
 *
 * @return an <code>Iterator</code> containing <code>ImageWriter</code>s.
 *
 * @exception IllegalArgumentException if <code>fileSuffix</code> is
 * <code>null</code>.
 *
 * @see javax.imageio.spi.ImageWriterSpi#getFileSuffixes
 */
public static Iterator<ImageWriter>
    getImageWritersBySuffix(String fileSuffix)
{
    if (fileSuffix == null) {
        throw new IllegalArgumentException("fileSuffix == null!");
    }
    Iterator iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
                               new ContainsFilter(writerFileSuffixesMethod,
                                                  fileSuffix),
                                        true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageWriterIterator(iter);
}
 
Example 6
@Override
protected Iterator<E> flatMap(Traverser.Admin<Element> traverser) {
    if (useMultiQuery) { //it is guaranteed that all elements are vertices
        if (multiQueryResults == null || !multiQueryResults.containsKey(traverser.get())) {
            initializeMultiQuery(Arrays.asList(traverser));
        }
        return convertIterator(multiQueryResults.get(traverser.get()));
    } else if (traverser.get() instanceof JanusGraphVertex || traverser.get() instanceof WrappedVertex) {
        JanusGraphVertexQuery query = makeQuery((JanusGraphTraversalUtil.getJanusGraphVertex(traverser)).query());
        return convertIterator(query.properties());
    } else {
        //It is some other element (edge or vertex property)
        Iterator<E> iterator;
        if (getReturnType().forValues()) {
            iterator = traverser.get().values(getPropertyKeys());
        } else {
            //HasContainers don't apply => empty result set
            if (!hasContainers.isEmpty()) return Collections.emptyIterator();
            iterator = (Iterator<E>) traverser.get().properties(getPropertyKeys());
        }
        if (limit != Query.NO_LIMIT) iterator = Iterators.limit(iterator, limit);
        return iterator;
    }
}
 
Example 7
Source Project: jdk1.8-source-analysis   File: ImageIO.java    License: Apache License 2.0 6 votes vote down vote up
/**
 * Returns an <code>Iterator</code> containing all currently
 * registered <code>ImageWriter</code>s that claim to be able to
 * encode the named format.
 *
 * @param formatName a <code>String</code> containing the informal
 * name of a format (<i>e.g.</i>, "jpeg" or "tiff".
 *
 * @return an <code>Iterator</code> containing
 * <code>ImageWriter</code>s.
 *
 * @exception IllegalArgumentException if <code>formatName</code> is
 * <code>null</code>.
 *
 * @see javax.imageio.spi.ImageWriterSpi#getFormatNames
 */
public static Iterator<ImageWriter>
    getImageWritersByFormatName(String formatName)
{
    if (formatName == null) {
        throw new IllegalArgumentException("formatName == null!");
    }
    Iterator iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
                                new ContainsFilter(writerFormatNamesMethod,
                                                   formatName),
                                        true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageWriterIterator(iter);
}
 
Example 8
/**
 * Returns an <code>Iterator</code> containing all currently
 * registered <code>ImageTranscoder</code>s that claim to be
 * able to transcode between the metadata of the given
 * <code>ImageReader</code> and <code>ImageWriter</code>.
 *
 * @param reader an <code>ImageReader</code>.
 * @param writer an <code>ImageWriter</code>.
 *
 * @return an <code>Iterator</code> containing
 * <code>ImageTranscoder</code>s.
 *
 * @exception IllegalArgumentException if <code>reader</code> or
 * <code>writer</code> is <code>null</code>.
 */
public static Iterator<ImageTranscoder>
    getImageTranscoders(ImageReader reader, ImageWriter writer)
{
    if (reader == null) {
        throw new IllegalArgumentException("reader == null!");
    }
    if (writer == null) {
        throw new IllegalArgumentException("writer == null!");
    }
    ImageReaderSpi readerSpi = reader.getOriginatingProvider();
    ImageWriterSpi writerSpi = writer.getOriginatingProvider();
    ServiceRegistry.Filter filter =
        new TranscoderFilter(readerSpi, writerSpi);

    Iterator iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageTranscoderSpi.class,
                                        filter, true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageTranscoderIterator(iter);
}
 
Example 9
@Override
public Iterator<R> call(Iterator<MultiDataSet> dataSetIterator) throws Exception {
    //Under some limited circumstances, we might have an empty partition. In this case, we should return immediately
    if(!dataSetIterator.hasNext()){
        return Collections.emptyIterator();
    }
    /*
        That's the place where we do our stuff. Here's the plan:
        1) we pass given iterator to VirtualDataSetIterator, which acts as holder for them
        2) Virtual iterator will provide load balancing between available devices
        3) we'll lock out here
     */

    // iterator should be silently attached to VirtualDataSetIterator, and used appropriately
    SharedTrainingWrapper.getInstance(worker.getInstanceId()).attachMDS(dataSetIterator);

    // first callee will become master, others will obey and die
    // all threads in this executor will be blocked here until training finished
    SharedTrainingResult result = SharedTrainingWrapper.getInstance(worker.getInstanceId()).run(worker);

    return Collections.singletonList((R) result).iterator();
}
 
Example 10
@Override
public Iterator<ExecRow> fetchInner(ExecRow outer) throws IOException, StandardException{

    for (int i = 0; i < numKeys; i++) {
        keyRow.setColumn(i+1, outer.getColumn(outerHashKeys[i] + 1));
    }
    
    List<ExecRow> rows = table.get(keyRow);
    if(rows==null)
        return Collections.emptyIterator();
    else
        return rows.iterator();
}
 
Example 11
Source Project: quarkus   File: SelectionResult.java    License: Apache License 2.0 5 votes vote down vote up
@Override
public Iterator<Extension> iterator() {
    if (matches) {
        return extensions.iterator();
    }
    return Collections.emptyIterator();
}
 
Example 12
Source Project: Bats   File: LocalPersistentStore.java    License: Apache License 2.0 5 votes vote down vote up
@Override
public Iterator<Map.Entry<String, V>> getRange(int skip, int take) {
  try {
    // list only files with sys file suffix
    PathFilter sysFileSuffixFilter = new PathFilter() {
      @Override
      public boolean accept(Path path) {
        return path.getName().endsWith(DRILL_SYS_FILE_SUFFIX);
      }
    };

    List<FileStatus> fileStatuses = DrillFileSystemUtil.listFiles(fs, basePath, false, sysFileSuffixFilter);
    if (fileStatuses.isEmpty()) {
      return Collections.emptyIterator();
    }

    List<String> files = Lists.newArrayList();
    for (FileStatus stat : fileStatuses) {
      String s = stat.getPath().getName();
      files.add(s.substring(0, s.length() - DRILL_SYS_FILE_SUFFIX.length()));
    }

    Collections.sort(files);

    return Iterables.transform(Iterables.limit(Iterables.skip(files, skip), take), new Function<String, Entry<String, V>>() {
      @Nullable
      @Override
      public Entry<String, V> apply(String key) {
        return new ImmutableEntry<>(key, get(key));
      }
    }).iterator();
  } catch (IOException e) {
    throw new RuntimeException(e);
  }
}
 
Example 13
Source Project: dremio-oss   File: ScanWithDremioReader.java    License: Apache License 2.0 5 votes vote down vote up
static Iterator<RecordReader> createReaders(
    final HiveConf hiveConf,
    final BaseHiveStoragePlugin hiveStoragePlugin,
    final FragmentExecutionContext fragmentExecContext,
    final OperatorContext context,
    final HiveProxyingSubScan config,
    final HiveTableXattr tableXattr,
    final CompositeReaderConfig compositeReader,
    final UserGroupInformation readerUGI,
    List<SplitAndPartitionInfo> splits) {

  try (ContextClassLoaderSwapper ccls = ContextClassLoaderSwapper.newInstance()) {

    if(splits.isEmpty()) {
      return Collections.emptyIterator();
    }

    final JobConf jobConf = new JobConf(hiveConf);

    final List<HiveParquetSplit> sortedSplits = Lists.newArrayList();
    for (SplitAndPartitionInfo split : splits) {
      sortedSplits.add(new HiveParquetSplit(split));
    }
    Collections.sort(sortedSplits);

    return new HiveParquetSplitReaderIterator(
            jobConf,
            context,
            config,
            sortedSplits,
            readerUGI,
            compositeReader,
            hiveStoragePlugin,
            tableXattr);
  } catch (final Exception e) {
    throw Throwables.propagate(e);
  }
}
 
Example 14
Source Project: iceberg   File: CloseableIterable.java    License: Apache License 2.0 5 votes vote down vote up
static <E> CloseableIterable<E> empty() {
  return new CloseableIterable<E>() {
    @Override
    public void close() {
    }

    @Override
    public Iterator<E> iterator() {
      return Collections.emptyIterator();
    }
  };
}
 
Example 15
Source Project: flink   File: TaskSlotTableImpl.java    License: Apache License 2.0 5 votes vote down vote up
private TaskSlotIterator(JobID jobId, TaskSlotState state) {

			Set<AllocationID> allocationIds = slotsPerJob.get(jobId);

			if (allocationIds == null || allocationIds.isEmpty()) {
				allSlots = Collections.emptyIterator();
			} else {
				allSlots = allocationIds.iterator();
			}

			this.state = Preconditions.checkNotNull(state);

			this.currentSlot = null;
		}
 
Example 16
@Override
public Iterator<DataCell> iterator(){
    if(result==null||result.isEmpty()) return Collections.emptyIterator();
    return Iterators.transform(result.listCells().iterator(),transform);
}
 
Example 17
/**
 * Returns an iterator over property values used in the {@code for each...in} statement. Aside from built-in JS
 * objects, it also operates on Java arrays, any {@link Iterable}, as well as on {@link Map} objects, iterating over
 * map values.
 * @param obj object to iterate on.
 * @return iterator over the object's property values.
 */
public static Iterator<?> toValueIterator(final Object obj) {
    if (obj instanceof ScriptObject) {
        return ((ScriptObject)obj).valueIterator();
    }

    if (obj != null && obj.getClass().isArray()) {
        final Object array  = obj;
        final int    length = Array.getLength(obj);

        return new Iterator<Object>() {
            private int index = 0;

            @Override
            public boolean hasNext() {
                return index < length;
            }

            @Override
            public Object next() {
                if (index >= length) {
                    throw new NoSuchElementException();
                }
                return Array.get(array, index++);
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException("remove");
            }
        };
    }

    if (obj instanceof JSObject) {
        return ((JSObject)obj).values().iterator();
    }

    if (obj instanceof Map) {
        return ((Map<?,?>)obj).values().iterator();
    }

    if (obj instanceof Iterable) {
        return ((Iterable<?>)obj).iterator();
    }

    final Object wrapped = Global.instance().wrapAsObject(obj);
    if (wrapped instanceof ScriptObject) {
        return ((ScriptObject)wrapped).valueIterator();
    }

    return Collections.emptyIterator();
}
 
Example 18
Source Project: tinkerpop   File: EmptyGraph.java    License: Apache License 2.0 4 votes vote down vote up
@Override
public Iterator<Edge> edges(final Object... edgeIds) {
    return Collections.emptyIterator();
}
 
Example 19
Source Project: Bats   File: ValueExpressions.java    License: Apache License 2.0 4 votes vote down vote up
@Override
public Iterator<LogicalExpression> iterator() {
  return Collections.emptyIterator();
}
 
Example 20
Source Project: ReactFX   File: LL.java    License: BSD 2-Clause "Simplified" License votes vote down vote up
@Override public Iterator<T> iterator() { return Collections.emptyIterator(); }