Example usage for java.util Collections emptyIterator

Introduction

In this page you can find the example usage for java.util Collections emptyIterator.

Prototype

@SuppressWarnings("unchecked")
public static <T> Iterator<T> emptyIterator() 

Source Link

Document

Returns an iterator that has no elements.

Usage

From source file:org.apache.tinkerpop.gremlin.structure.util.star.StarGraph.java

@Override
public Iterator<Edge> edges(final Object... edgeIds) {
    return null == this.starVertex ? Collections.emptyIterator()
            : Stream.concat(// w  w  w .j  av  a2s. co  m
                    null == this.starVertex.inEdges ? Stream.empty()
                            : this.starVertex.inEdges.values().stream(),
                    null == this.starVertex.outEdges ? Stream.empty()
                            : this.starVertex.outEdges.values().stream())
                    .flatMap(List::stream).filter(edge -> {
                        // todo: kinda fishy - need to better nail down how stuff should work here - none of these feel consistent right now.
                        if (edgeIds.length > 0 && edgeIds[0] instanceof Edge)
                            return ElementHelper.idExists(edge.id(),
                                    Stream.of(edgeIds).map(e -> ((Edge) e).id()).toArray());
                        else
                            return ElementHelper.idExists(edge.id(), edgeIds);
                    }).iterator();
}

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From source file:org.apache.wicket.MarkupContainer.java

/**
 * Gives an iterator that allow you to iterate through the children of this markup container in
 * the order the children were added. The iterator supports additions and removals from the list
 * of children during iteration.//from ww  w .  ja  v a  2s .c  om
 * 
 * @return Iterator that iterates through children in the order they were added
 */
@Override
public Iterator<Component> iterator() {
    /**
     * Iterator that knows how to change between a single child, list of children and map of
     * children. Keeps track when the iterator was last sync'd with the markup container's
     * tracking of changes to the list of children.
     */
    class MarkupChildIterator implements Iterator<Component> {
        private int indexInRemovalsSinceLastUpdate = removals_size();
        private int expectedModCounter = -1;
        private Component currentComponent = null;
        private Iterator<Component> internalIterator = null;

        @Override
        public boolean hasNext() {
            refreshInternalIteratorIfNeeded();
            return internalIterator.hasNext();
        }

        @Override
        public Component next() {
            refreshInternalIteratorIfNeeded();
            return currentComponent = internalIterator.next();
        }

        @Override
        public void remove() {
            MarkupContainer.this.remove(currentComponent);
            refreshInternalIteratorIfNeeded();
        }

        private void refreshInternalIteratorIfNeeded() {
            if (modCounter != 0 && expectedModCounter >= modCounter)
                return;

            if (children == null) {
                internalIterator = Collections.emptyIterator();
            } else if (children instanceof Component) {
                internalIterator = Collections.singleton((Component) children).iterator();
            } else if (children instanceof List) {
                List<Component> childrenList = children();
                internalIterator = childrenList.iterator();
            } else {
                Map<String, Component> childrenMap = children();
                internalIterator = childrenMap.values().iterator();
            }

            // since we now have a new iterator, we need to set it to the last known position
            currentComponent = findLastExistingChildAlreadyReturned(currentComponent);
            expectedModCounter = modCounter;
            indexInRemovalsSinceLastUpdate = removals_size();

            if (currentComponent != null) {
                // move the new internal iterator to the place of the last processed component
                while (internalIterator.hasNext() && internalIterator.next() != currentComponent)
                    // noop
                    ;
            }
        }

        private Component findLastExistingChildAlreadyReturned(Component target) {
            while (true) {
                if (target == null)
                    return null;

                RemovedChild removedChild = null;
                for (int i = indexInRemovalsSinceLastUpdate; i < removals_size(); i++) {
                    RemovedChild curRemovedChild = removals_get(i);
                    if (curRemovedChild.removedChild == target || curRemovedChild.removedChild == null) {
                        removedChild = curRemovedChild;
                        break;
                    }
                }
                if (removedChild == null) {
                    return target;
                } else {
                    target = removedChild.previousSibling;
                }
            }
        }
    }
    ;
    return new MarkupChildIterator();
}

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From source file:org.bimserver.plugins.MavenPluginLocation.java

public Iterator<MavenPluginVersion> iterateAllVersions() {
    Artifact artifact = new DefaultArtifact(groupId, artifactId, null, "[0,)");

    VersionRangeRequest rangeRequest = new VersionRangeRequest();
    rangeRequest.setArtifact(artifact);/*w w w. j a v a 2  s  . c o m*/
    rangeRequest.setRepositories(mavenPluginRepository.getRepositoriesAsList());

    try {
        VersionRangeResult rangeResult = mavenPluginRepository.getSystem()
                .resolveVersionRange(mavenPluginRepository.getSession(), rangeRequest);
        List<Version> versions = rangeResult.getVersions();
        if (!versions.isEmpty()) {
            Iterator<Version> versionIterator = Lists.reverse(versions).iterator();
            return Iterators.transform(versionIterator, new Function<Version, MavenPluginVersion>() {
                @Override
                public MavenPluginVersion apply(Version version) {
                    try {
                        MavenPluginVersion mavenPluginVersion = createMavenVersion(version);
                        return mavenPluginVersion;
                    } catch (ArtifactDescriptorException | ArtifactResolutionException | IOException
                            | XmlPullParserException e) {
                        LOGGER.error("", e);
                    }
                    return null;
                }
            });
        }
    } catch (VersionRangeResolutionException e) {
        LOGGER.error("", e);
    }

    return Collections.emptyIterator();
}

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From source file:org.geoserver.qos.web.OperationAnomalyFeedPanel.java

public OperationAnomalyFeedPanel(String id, IModel<ReferenceType> model) {
    super(id, model);
    anomalyFeedModel = model;/*www  . j a va2  s. co m*/

    ReferenceType anomalyFeed = model.getObject();
    if (anomalyFeed.getAbstracts() == null) {
        anomalyFeed.setAbstracts(
                new ArrayList<OwsAbstract>(Arrays.asList(new OwsAbstract[] { new OwsAbstract("") })));
    }

    final WebMarkupContainer div = new WebMarkupContainer("anomalyDiv");
    div.setOutputMarkupId(true);
    add(div);

    TextField<String> hrefField = new TextField<String>("href", new PropertyModel<>(anomalyFeedModel, "href")) {
    };
    div.add(hrefField);

    TextField<String> abstractField = new TextField<String>("abstract",
            new PropertyModel<>(anomalyFeedModel, "abstractOne")) {
    };
    div.add(abstractField);

    final AutoCompleteTextField<String> formatField = new AutoCompleteTextField<String>("format",
            new PropertyModel<>(anomalyFeedModel, "format")) {

        @Override
        protected Iterator<String> getChoices(String input) {
            if (StringUtils.isEmpty(input) || StringUtils.isEmpty(input.trim())) {
                return Collections.emptyIterator();
            }
            return MimeTypes.getMimeTypeValuesStream().filter(m -> m.startsWith(input)).limit(10).iterator();
        }
    };
    //        TextField<String> formatField =
    //                new TextField<String>("format", new PropertyModel<>(anomalyFeed,
    // "format")) {};
    div.add(formatField);

    final AjaxSubmitLink deleteLink = new AjaxSubmitLink("deleteLink") {
        @Override
        public void onAfterSubmit(AjaxRequestTarget target, Form<?> form) {
            delete(target);
        }
    };
    div.add(deleteLink);
}

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From source file:org.janusgraph.graphdb.tinkerpop.JanusGraphBlueprintsTransaction.java

@Override
public Iterator<Vertex> vertices(Object... vids) {
    if (vids == null || vids.length == 0)
        return (Iterator) getVertices().iterator();
    ElementUtils.verifyArgsMustBeEitherIdorElement(vids);
    long[] ids = new long[vids.length];
    int pos = 0;/*from w  w w.ja va 2 s.co  m*/
    for (int i = 0; i < vids.length; i++) {
        long id = ElementUtils.getVertexId(vids[i]);
        if (id > 0)
            ids[pos++] = id;
    }
    if (pos == 0)
        return Collections.emptyIterator();
    if (pos < ids.length)
        ids = Arrays.copyOf(ids, pos);
    return (Iterator) getVertices(ids).iterator();
}

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From source file:org.janusgraph.graphdb.tinkerpop.JanusGraphBlueprintsTransaction.java

@Override
public Iterator<Edge> edges(Object... eids) {
    if (eids == null || eids.length == 0)
        return (Iterator) getEdges().iterator();
    ElementUtils.verifyArgsMustBeEitherIdorElement(eids);
    RelationIdentifier[] ids = new RelationIdentifier[eids.length];
    int pos = 0;/*from w  ww  . j  av  a2  s.c o m*/
    for (int i = 0; i < eids.length; i++) {
        RelationIdentifier id = ElementUtils.getEdgeId(eids[i]);
        if (id != null)
            ids[pos++] = id;
    }
    if (pos == 0)
        return Collections.emptyIterator();
    if (pos < ids.length)
        ids = Arrays.copyOf(ids, pos);
    return (Iterator) getEdges(ids).iterator();
}

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From source file:org.jboss.forge.addon.configuration.ConfigurationAdapterSubset.java

@Override
public Iterator<String> getKeys() {
    synchronized (parent) {
        try {/*from  w w  w.  j  a  v  a 2 s  .co m*/
            return parent.subset(prefix).getKeys();
        } catch (IllegalArgumentException e) {
            return Collections.emptyIterator();
        }
    }
}

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From source file:org.phenotips.data.permissions.internal.DefaultPermissionsManager.java

@Override
public Iterator<Patient> filterByVisibility(Iterator<Patient> patients, Visibility requiredVisibility) {
    if (requiredVisibility == null) {
        return patients;
    }//from  ww w  .  ja  va2  s . com
    if (patients == null || !patients.hasNext()) {
        return Collections.emptyIterator();
    }
    return new FilteringIterator(patients, requiredVisibility, this);
}

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From source file:org.phenotips.entities.internal.AbstractPrimaryEntityManager.java

@Override
public Iterator<E> getAll() {
    try {/*from   w  w  w  . ja v  a  2s  .c om*/
        Query q = this.qm
                .createQuery("select doc.fullName from Document as doc, doc.object("
                        + this.localSerializer.serialize(getEntityXClassReference())
                        + ") as entity where doc.name not in (:template1, :template2) order by doc.name asc",
                        Query.XWQL)
                .bindValue("template1", this.getEntityXClassReference().getName() + "Template")
                .bindValue("template2",
                        StringUtils.removeEnd(this.getEntityXClassReference().getName(), "Class") + "Template");
        List<String> docNames = q.execute();
        return new LazyPrimaryEntityIterator<>(docNames, this);
    } catch (QueryException ex) {
        this.logger.warn("Failed to query all entities of type [{}]: {}", getEntityXClassReference(),
                ex.getMessage());
    }
    return Collections.emptyIterator();
}

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From source file:org.roda.core.common.iterables.CloseableIterables.java

public static <T> CloseableIterable<T> empty() {
    return new CloseableIterable<T>() {

        @Override//ww  w.  j  a v  a 2  s. co  m
        public void close() throws IOException {
            // nothing to do
        }

        @Override
        public Iterator<T> iterator() {
            return Collections.emptyIterator();
        }
    };
}

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