Java Code Examples for java.util.stream.Stream#empty()

private List<Sample> samples(final String sample) {
  final Function<String, Stream<Sample>> toPair = compiler -> {
    final String clazz = makeClassName(sample, compiler);
    final Optional<byte[]> bs = FilterTester.this.source.getBytes(clazz);
    if (bs.isPresent()) {
      final Sample p = new Sample();
      p.className = ClassName.fromString(clazz);
      p.clazz = ClassTree.fromBytes(bs.get());
      p.compiler = compiler;
      return Stream.of(p);
    }
    return Stream.empty();

  };
  return COMPILERS.stream().flatMap(toPair).collect(Collectors.toList());
}
 

@Override
public Stream<ConceptMap> match(MatchClause matchClause) {
    Stream<ConceptMap> answerStream;

    try {
        validateClause(matchClause);

        Set<Variable> bindingVars = matchClause.getPatterns().variables();

        Disjunction<Conjunction<Pattern>> disjunction = matchClause.getPatterns().getNegationDNF();
        ResolvableQuery resolvableQuery = reasonerQueryFactory.resolvable(disjunction, bindingVars);

        return resolvableQuery.resolve(infer);
    } catch (ReasonerCheckedException e) {
        LOG.debug(e.getMessage());
        answerStream = Stream.empty();
    }

    return answerStream;
}
 

private Stream<O> _finish() {
  if (isFinished) {
    return Stream.empty();
  }

  isFinished = true;
  return stateMachine.finish(state);
}
 

public Stream<CursorQuad> getChanges(String subject, String predicate, Direction direction, int version,
                                     boolean assertions) {
  if (bdbWrappers.containsKey(version)) {
    final BdbWrapper<String, String> bdbWrapper = bdbWrappers.get(version);
    return bdbWrapper.databaseGetter()
                     .key(subject + "\n" + version + "\n" + (assertions ? "1" : "0"))
                     .skipNearValue(predicate + "\n" + (direction == OUT ? "1" : "0") + "\n")
                     .onlyValuesMatching((prefix, value) -> value.startsWith(prefix))
                     .forwards()
                     .getValues(bdbWrapper.valueRetriever())
                     .map(v -> makeCursorQuad(subject, assertions, v));
  }

  return Stream.empty();
}
 

/**
 * Helper method to list sub-directories.
 * @param path
 * @return {@code Stream<Path>} representing sub-directories
 */
private Stream<Path> getSubDirectories(Path path) {
    try {
        return Files.list(path).filter(e -> Files.isDirectory(e));
    }
    catch (IOException ioe) {
        return Stream.empty();
    }
}
 

@Test
public void whenCollectionIsNull_thenExpectAnEmptyStream() {
    Collection<String> collection = null;
    Stream<String> expResult = Stream.empty();
    Stream<String> result = instance.collectionAsStream(collection);
    assertStreamEquals(expResult, result);

}
 

/**
 * Returns the direct dependences of the given source
 */
Stream<Archive> requires(Archive source) {
    if (!results.containsKey(source)) {
        return Stream.empty();
    }
    return results.get(source).requires()
                  .stream();
}
 

public final Stream<String> valueStream(IN_NAME name) {
    final CONTAINER getters = getters();
    return getters != null ? getters.valueStream(name) : Stream.empty();
}
 

@Override
public Stream<SubFunctionPattern> getSubFunctions() {
	return Stream.empty();
}
 

@Override
public Stream<SerialPortIdentifier> getSerialPortIdentifiers() {
    // TODO implement discovery here. https://github.com/eclipse/smarthome/pull/5560
    return Stream.empty();
}
 

/**
 * Returns a random sequence of time values from this domain.
 */
protected Stream<Date> timeValues( ResolverContext context)
  {
  Calendar minDate =
    new Calendar.Builder()
    .setInstant( getMinDate())
    .build();

  long minTime =
    new Calendar.Builder()
    .setDate( minDate.get( YEAR), minDate.get( MONTH), minDate.get( DAY_OF_MONTH))
    .setTimeOfDay( 0, 0, 0, 0)
    .build()
    .getTimeInMillis();

  Calendar maxDate =
    new Calendar.Builder()
    .setInstant( getMaxDate())
    .build();

  long maxTime =
    new Calendar.Builder()
    .setDate( maxDate.get( YEAR), maxDate.get( MONTH), maxDate.get( DAY_OF_MONTH))
    .setTimeOfDay( 0, 0, 0, 0)
    .build()
    .getTimeInMillis();

  long millisPerDay = 86400000;
  long daysCount = (maxTime - minTime) / millisPerDay + 1;

  return
    daysCount < 1?
    Stream.empty() :

    daysCount == 1?
    Stream.of( getMinDate()) :

    context.getRandom().longs( 0, daysCount)
    .map( d -> minTime + d * millisPerDay)
    .mapToObj( Date::new);
  }
 

@Override
public Stream<String> strings(Stream<Object> stream) {
    return Stream.empty();
}
 

/**
 * Returns an empty stream for a schema of unknown type.
 */
private Stream<IVarDef> unknownSchemaVars( String type)
  {
  notifyError( String.format( "Unknown schema type=%s is not supported", type), "Ignoring unknown schema");
  return Stream.empty();
  }
 

@Override
public Stream<MessageStoreEntry> stream() {
    return Stream.empty();
}
 

@Override
public final Stream<IView> streamAllViews()
{
	return Stream.empty();
}
 

@Override
public Stream<? extends Scannable> inners() {
	return Stream.empty();
}
 

@Override
public Stream<? extends Scannable> inners() {
	return  window == null ? Stream.empty() : Stream.of(window);
}
 

/**
 * Given any number of streams, returns distinct values such that the set of
 * elements in the returned stream are those distinct elements of the first
 * stream that are not contained in any of the subsequent passed streams.
 *
 * @param streams An array of streams
 * @param <T> All elements in all streams are instances of this single type
 * @return distinct values of the first stream such that the set of elements
 * in the returned stream are not contained in any of the subsequent passed streams
 */
public static <T> Stream<T> difference(Stream<T>... streams) {
    if(streams.length < 1) {
        return Stream.empty();
    } else if(streams.length < 2) {
        return streams[0];
    } else {
        return difference(streams[0], concat(Arrays.copyOfRange(streams, 1, streams.length - 1)));
    }
}
 

/**
 * Transform the contents of a stream.
 *
 * @param <T> The collection member type.
 * @param <R> The resulting collection member type.
 * @param <C> The resulting collection type.
 * @param stream The {@code Stream} to transform.
 * @param predicate A {@code Predicate} to select the items.
 * @param mapper A function to transform the selected items.
 * @param collector A {@code Collector} to aggregate the results.
 * @return The result of collecting the mapped predicate matches.
 */
public static <T,R,C> C transform(Stream<T> stream,
    Predicate<? super T> predicate,
    Function<? super T, ? extends R> mapper,
    Collector<R,?,C> collector) {
    final Stream<T> s = (stream == null) ? Stream.<T>empty() : stream;
    return transform_internal(s, predicate, mapper, null, collector);
}
 

/**
 * Gets the set of abilities with the given identifier from this
 * object.  Subclasses with complex ability handling should
 * override this as all prior routines are derived from it.
 *
 * @param id The object identifier.
 * @param fcgot An optional {@code FreeColSpecObjectType} the
 *     ability applies to.
 * @param turn An optional applicable {@code Turn}.
 * @return A set of abilities.
 */
public Stream<Ability> getAbilities(String id,
                                    FreeColSpecObjectType fcgot,
                                    Turn turn) {
    FeatureContainer fc = getFeatureContainer();
    return (fc == null) ? Stream.<Ability>empty()
        : fc.getAbilities(id, fcgot, turn);
}