Java Code Examples for java.util.stream.collector#of()

The following examples show how to use java.util.stream.collector#of() . 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 File: ByteBufQueue.java    From datakernel with Apache License 2.0 8 votes vote down vote up
public static Collector<ByteBuf, ByteBufQueue, ByteBuf> collector(int maxSize) {
	return Collector.of(
			ByteBufQueue::new,
			(queue, buf) -> {
				int size = buf.readRemaining();
				if (size > maxSize || queue.hasRemainingBytes(maxSize - size + 1)) {
					queue.recycle();
					buf.recycle();
					throw new UncheckedException(new InvalidSizeException(ByteBufQueue.class,
							"ByteBufQueue exceeds maximum size of " + maxSize + " bytes"));
				}
				queue.add(buf);
			},
			(bufs1, bufs2) -> {
				throw new UnsupportedOperationException("Parallel collection of byte bufs is not supported");
			},
			ByteBufQueue::takeRemaining);
}
 
Example 2
Source File: StreamUtils.java    From vertexium with Apache License 2.0 6 votes vote down vote up
public static <T> Collector<T, LinkedHashSet<T>, LinkedHashSet<T>> toLinkedHashSet() {
    return Collector.of(
        LinkedHashSet::new,
        HashSet::add,
        (a1, a2) -> {
            LinkedHashSet<T> results = new LinkedHashSet<T>();
            results.addAll(a1);
            results.addAll(a2);
            return results;
        },
        ts -> ts
    );
}
 
Example 3
Source File: RecordServiceImpl.java    From component-runtime with Apache License 2.0 6 votes vote down vote up
@Override
public Collector<Schema.Entry, Record.Builder, Record> toRecord(final Schema schema, final Record fallbackRecord,
        final BiFunction<Schema.Entry, Record.Builder, Boolean> customHandler,
        final BiConsumer<Record.Builder, Boolean> beforeFinish) {
    final AtomicBoolean customHandlerCalled = new AtomicBoolean();
    return Collector.of(() -> recordBuilderFactory.newRecordBuilder(schema), (builder, entry) -> {
        if (!customHandler.apply(entry, builder)) {
            forwardEntry(fallbackRecord, builder, entry.getName(), entry);
        } else {
            customHandlerCalled.set(true);
        }
    }, (b1, b2) -> {
        throw new IllegalStateException("merge unsupported");
    }, builder -> {
        beforeFinish.accept(builder, customHandlerCalled.get());
        return builder.build();
    });
}
 
Example 4
Source File: ArrayUtils.java    From morpheus-core with Apache License 2.0 6 votes vote down vote up
/**
 * Returns a collector that collects items in a Morpheus array
 * @param type              the array type
 * @param expectedLength    an estimate of the expected length, does not have to be exact
 * @param <T>               the array element type
 * @return                  the newly created collector
 */
public static <T> Collector<T,ArrayBuilder<T>,Array<T>> toArray(Class<T> type, int expectedLength) {
    final Supplier<ArrayBuilder<T>> supplier = () -> ArrayBuilder.of(expectedLength, type);
    final BinaryOperator<ArrayBuilder<T>> combiner = ArrayBuilder::addAll;
    final BiConsumer<ArrayBuilder<T>,T> accumulator = ArrayBuilder::add;
    final Function<ArrayBuilder<T>,Array<T>> finisher = ArrayBuilder::toArray;
    return Collector.of(supplier, accumulator, combiner, finisher);
}
 
Example 5
Source File: MoreCollectors.java    From arctic-sea with Apache License 2.0 5 votes vote down vote up
public static <X> Collector<X, ?, Stream<X>> toDuplicateStream(int min) {
    if (min < 2) {
        throw new IllegalArgumentException();
    }
    Supplier<Map<X, Integer>> supplier = HashMap::new;
    BiConsumer<Map<X, Integer>, X> accumulator = (map, key) -> map.merge(key, 1, Integer::sum);
    BinaryOperator<Map<X, Integer>> combiner = Functions.mergeToLeftMap(Integer::sum);
    Function<Map<X, Integer>, Stream<X>> finisher = Functions.keyStreamWhereValues(v -> v >= min);
    return Collector.of(supplier, accumulator, combiner, finisher, Characteristics.UNORDERED);
}
 
Example 6
Source File: RowCollectors.java    From vertx-postgresql-starter with MIT License 5 votes vote down vote up
/**
 * Build a collector for transforming rows to a {@link io.vertx.core.json.JsonArray} with specific types.
 *
 * @param rowMapper mapper to transform a row
 * @param <T>       the target type
 * @return the collector
 */
public static <T> Collector<Row, ?, JsonArray> jsonArrayCollector(Function<Row, T> rowMapper) {
  return Collector.of(JsonArray::new,
    (jsonArray, row) -> jsonArray.add(rowMapper.apply(row)),
    (left, right) -> {
      left.addAll(right);
      return left;
    }, Collector.Characteristics.IDENTITY_FINISH);
}
 
Example 7
Source File: CollectorsEx.java    From datakernel with Apache License 2.0 5 votes vote down vote up
public static <T> Collector<T, RefBoolean, Boolean> toNone(Predicate<T> predicate) {
	return Collector.of(
			() -> new RefBoolean(true),
			(a, t) -> a.value &= !predicate.test(t),
			(a1, a2) -> {
				a1.value &= a2.value;
				return a1;
			},
			b -> b.value);
}
 
Example 8
Source File: CollectorUtils.java    From pgadba with BSD 2-Clause "Simplified" License 5 votes vote down vote up
/**
 * Returns the java type of the column named "t".
 * @param clazz type of element to fetch
 * @param <T> returning type
 * @return a collector
 */
public static <T> Collector<Result.RowColumn, Class<T>[], Class<T>> javaTypeCollector(Class<T> clazz) {
  return Collector.of(
      () -> new Class[1],
      (a, r) -> a[0] = r.at("t").javaType(),
      (l, r) -> null,
      a -> a[0]);
}
 
Example 9
Source File: Row.java    From beam with Apache License 2.0 5 votes vote down vote up
/** Creates a {@link Row} from the list of values and {@link #getSchema()}. */
public static <T> Collector<T, List<Object>, Row> toRow(Schema schema) {
  return Collector.of(
      () -> new ArrayList<>(schema.getFieldCount()),
      List::add,
      (left, right) -> {
        left.addAll(right);
        return left;
      },
      values -> Row.withSchema(schema).addValues(values).build());
}
 
Example 10
Source File: MoreCollectors.java    From mill with MIT License 5 votes vote down vote up
public static <T, A, R> Collector<T, A, R> including(Predicate<T> predicate, Collector<T, A, R> collector) {
    return Collector.of(
            collector.supplier(),
            (s, t) -> {
                if(predicate.test(t)) {
                    collector.accumulator().accept(s, t);
                }
            },
            collector.combiner(),
            collector.finisher(),
            setToArray(collector.characteristics())
    );
}
 
Example 11
Source File: ImmutableCollectors.java    From helper with MIT License 5 votes vote down vote up
public static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toBiMap(Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends V> valueMapper) {
    return Collector.of(
            ImmutableBiMap.Builder<K, V>::new,
            (builder, input) -> builder.put(keyMapper.apply(input), valueMapper.apply(input)),
            (l, r) -> l.putAll(r.build()),
            ImmutableBiMap.Builder::build
    );
}
 
Example 12
Source File: List.java    From openjdk-jdk9 with GNU General Public License v2.0 5 votes vote down vote up
/**
 * Collect elements into a new list (using a @code{ListBuffer})
 */
public static <Z> Collector<Z, ListBuffer<Z>, List<Z>> collector() {
    return Collector.of(ListBuffer::new,
            ListBuffer::add,
            (buf1, buf2)-> { buf1.addAll(buf2); return buf1; },
            ListBuffer::toList);
}
 
Example 13
Source File: MoreCollectors.java    From mill with MIT License 5 votes vote down vote up
public static <T, A, R> Collector<T, A, R> excluding(Predicate<T> predicate, Collector<T, A, R> collector) {
    return Collector.of(
            collector.supplier(),
            (s, t) -> {
                if(predicate.negate().test(t)) {
                    collector.accumulator().accept(s, t);
                }
            },
            collector.combiner(),
            collector.finisher(),
            setToArray(collector.characteristics())
    );
}
 
Example 14
Source File: GTUtility.java    From GregTech with GNU Lesser General Public License v3.0 4 votes vote down vote up
public static <T> Collector<T, ?, ImmutableList<T>> toImmutableList() {
    return Collector.of(ImmutableList::builder, Builder::add,
        (b1, b2) -> { b1.addAll(b2.build()); return b2; },
        ImmutableList.Builder<T>::build);
}
 
Example 15
Source File: MonetaryFunctions.java    From jsr354-ri with Apache License 2.0 4 votes vote down vote up
/**
 * of MonetaryAmount group by MonetarySummary
 * @return the MonetarySummaryStatistics
 */
public static Collector<MonetaryAmount,GroupMonetarySummaryStatistics,GroupMonetarySummaryStatistics>
groupBySummarizingMonetary(){
    return Collector.of(GroupMonetarySummaryStatistics::new, GroupMonetarySummaryStatistics::accept,
                        GroupMonetarySummaryStatistics::combine);
}
 
Example 16
Source File: Cases.java    From mug with Apache License 2.0 4 votes vote down vote up
static <T> Collector<T, ?, TinyContainer<T>> toTinyContainer() {
  return Collector.of(TinyContainer::new, TinyContainer::add, TinyContainer::addAll);
}
 
Example 17
Source File: Guavate.java    From Strata with Apache License 2.0 3 votes vote down vote up
/**
 * Collector used at the end of a stream to build an immutable sorted set.
 * <p>
 * A collector is used to gather data at the end of a stream operation.
 * This method returns a collector allowing streams to be gathered into
 * an {@link ImmutableSet}.
 * 
 * @param <T>  the type of element in the sorted set
 * @param comparator  the comparator
 * @return the immutable sorted set collector
 */
public static <T> Collector<T, ImmutableSortedSet.Builder<T>, ImmutableSortedSet<T>>
    toImmutableSortedSet(Comparator<? super T> comparator) {
  return Collector.of(
      (Supplier<ImmutableSortedSet.Builder<T>>) () -> new ImmutableSortedSet.Builder<>(comparator),
      ImmutableSortedSet.Builder<T>::add,
      (l, r) -> l.addAll(r.build()),
      ImmutableSortedSet.Builder<T>::build,
      Collector.Characteristics.UNORDERED);
}
 
Example 18
Source File: MoreCollectors.java    From mill with MIT License 3 votes vote down vote up
/**
 * Collects elements matching the given type, into a collection provided
 * by the given supplier.
 *
 * <pre>
 *     {@code
 *     List<RcsMessage> results = Stream.of(new RcsMessage(1), new SmsMessage(2), new MmsMessage(3))
 *           .collect(CollectorOps.typedCollector(RcsMessage.class, ArrayList::new));
 *     }
 * </pre>
 *
 * @param clazz the type of element to collect
 * @param supplier a supplier for this collector, generally a method reference to a collections object constructor, such as ArrayList::new
 * @param <T> the type of input elements to the reduction operation
 * @param <S> the type of output elements in the resulting collection
 * @param <R> the collection supplied by the supplier
 * @return a new collection of the elements that were instances of S
 */
public static <T, S extends T, R extends Collection<S>> Collector<T, ?, R>  typedCollector(Class<S> clazz, Supplier<R> supplier) {
    return Collector.of(
            supplier,
            (R collection, T o) -> {
                if (clazz.isInstance(o)) {
                    collection.add(clazz.cast(o));
                }
            },
            (R r1, R r2) -> { r1.addAll(r2); return r1; },
            IDENTITY_FINISH
    );
}
 
Example 19
Source File: Guavate.java    From Strata with Apache License 2.0 3 votes vote down vote up
/**
 * Collector used at the end of a stream to build an immutable list.
 * <p>
 * A collector is used to gather data at the end of a stream operation.
 * This method returns a collector allowing streams to be gathered into
 * an {@link ImmutableList}.
 *
 * @param <T>  the type of element in the list
 * @return the immutable list collector
 */
public static <T> Collector<T, ImmutableList.Builder<T>, ImmutableList<T>> toImmutableList() {
  return Collector.of(
      ImmutableList.Builder<T>::new,
      ImmutableList.Builder<T>::add,
      (l, r) -> l.addAll(r.build()),
      ImmutableList.Builder<T>::build);
}
 
Example 20
Source File: Values.java    From flo with Apache License 2.0 2 votes vote down vote up
/**
 * A {@link Collector} that collects a {@link Stream} of {@link Value}s into a {@link Value}
 * of a {@link List}.
 *
 * <p>The semantics of joining {@link Value}s is decided by this {@link EvalContext}.
 *
 * @param context The context which values are processed in
 * @param <T>     The inner type of the values
 * @return A collector for a stream of values
 */
public static <T> Collector<Value<T>, ?, Value<List<T>>> toValueList(EvalContext context) {
  return Collector.of(
      ArrayList::new, List::add, (a, b) -> { a.addAll(b); return a; },
      ValueFold.inContext(context));
}