Example usage for java.util.stream Collector of

Introduction

In this page you can find the example usage for java.util.stream Collector of.

Prototype

public static <T, R> Collector<T, R, R> of(Supplier<R> supplier, BiConsumer<R, T> accumulator,
        BinaryOperator<R> combiner, Characteristics... characteristics) 

Source Link

Document

Returns a new Collector described by the given supplier , accumulator , and combiner functions.

Usage

From source file:Main.java

public static void main(String[] args) throws Exception {
    List<Person> persons = Arrays.asList(new Person("Max", 18), new Person("Peter", 23),
            new Person("Pamela", 23), new Person("David", 12));

    Collector<Person, StringJoiner, String> personNameCollector = Collector.of(() -> new StringJoiner(" | "), // supplier
            (j, p) -> j.add(p.name.toUpperCase()), // accumulator
            (j1, j2) -> j1.merge(j2), // combiner
            StringJoiner::toString); // finisher

    String names = persons.stream().collect(personNameCollector);

    System.out.println(names);//from   w w  w.j a  v a 2 s.  co  m
}

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From source file:Main.java

public static void main(String[] args) throws Exception {
    List<Person> persons = Arrays.asList(new Person("Max", 18), new Person("Peter", 23),
            new Person("Pamela", 23), new Person("David", 12));

    Collector<Person, StringJoiner, String> personNameCollector = Collector.of(() -> {
        System.out.println("supplier");
        return new StringJoiner(" | ");
    }, (j, p) -> {//from w ww .ja  v a  2  s.  c  o  m
        System.out.format("accumulator: p=%s; j=%s\n", p, j);
        j.add(p.name.toUpperCase());
    }, (j1, j2) -> {
        System.out.println("merge");
        return j1.merge(j2);
    }, j -> {
        System.out.println("finisher");
        return j.toString();
    });

    String names = persons.stream().collect(personNameCollector);

    System.out.println(names);
}

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From source file:Main.java

public static <E> Collector<Optional<E>, Collection<E>, Stream<E>> filterEmpty() {
    return Collector.of(ConcurrentLinkedQueue::new, (q, oe) -> oe.ifPresent(q::add), (q1, q2) -> {
        q1.addAll(q2);//www .  ja  va2  s .  co  m
        return q1;
    }, Collection::stream);
}

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From source file:de.metas.ui.web.process.json.JSONDocumentActionsList.java

public static final Collector<WebuiRelatedProcessDescriptor, ?, JSONDocumentActionsList> collect(
        final JSONOptions jsonOpts) {
    final Supplier<List<WebuiRelatedProcessDescriptor>> supplier = ArrayList::new;
    final BiConsumer<List<WebuiRelatedProcessDescriptor>, WebuiRelatedProcessDescriptor> accumulator = List::add;
    final BinaryOperator<List<WebuiRelatedProcessDescriptor>> combiner = (l, r) -> {
        l.addAll(r);//from  w  w w  . ja v a  2  s.c o  m
        return l;
    };
    final Function<List<WebuiRelatedProcessDescriptor>, JSONDocumentActionsList> finisher = processDescriptors -> new JSONDocumentActionsList(
            processDescriptors, jsonOpts);
    return Collector.of(supplier, accumulator, combiner, finisher);
}

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From source file:de.metas.ui.web.window.datatypes.json.JSONLookupValuesList.java

public static final Collector<JSONLookupValue, ?, JSONLookupValuesList> collect() {
    final Supplier<List<JSONLookupValue>> supplier = ArrayList::new;
    final BiConsumer<List<JSONLookupValue>, JSONLookupValue> accumulator = List::add;
    final BinaryOperator<List<JSONLookupValue>> combiner = (l, r) -> {
        l.addAll(r);//from www.  ja v  a  2  s. c o m
        return l;
    };
    final Function<List<JSONLookupValue>, JSONLookupValuesList> finisher = JSONLookupValuesList::ofJSONLookupValuesList;
    return Collector.of(supplier, accumulator, combiner, finisher);
}

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From source file:com.github.steveash.guavate.Guavate.java

/**
 * Collector used at the end of a stream to build an immutable list.
 * <p>//w  w  w  . j a va 2 s  .co  m
 * 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);
}

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From source file:com.ikanow.aleph2.shared.crud.mongodb.utils.MongoDbUtils.java

/** Creates a big $and/$or list of the list of fields in the single query component
 * @param andVsOr - top level MongoDB operator
 * @param query_in - a single query (ie set of fields)
 * @return the MongoDB query object (no meta - that is added above)
 *//*from  ww  w .  ja  v  a2s.  c o m*/
protected static <T> DBObject convertToMongoQuery_single(final String andVsOr,
        final SingleQueryComponent<T> query_in) {
    final LinkedHashMultimap<String, Tuple2<Operator, Tuple2<Object, Object>>> fields = query_in.getAll();

    // The actual query:

    return Patterns.match(fields).<DBObject>andReturn().when(f -> f.isEmpty(), f -> new BasicDBObject())
            .otherwise(f -> f.asMap().entrySet().stream()
                    .<Tuple2<String, Tuple2<Operator, Tuple2<Object, Object>>>>flatMap(
                            entry -> entry.getValue().stream()
                                    .map(val -> Tuples._2T(entry.getKey(),
                                            Tuples._2T(val._1(), removeEnums(val._2())))))
                    .collect(Collector.of(BasicDBObject::new, (acc, entry) -> {
                        Patterns.match(acc.get(andVsOr)).andAct().when(l -> (null == l), l -> {
                            BasicDBList dbl = new BasicDBList();
                            dbl.add(operatorToMongoKey(entry._1(), entry._2()));
                            acc.put(andVsOr, dbl);
                        }).when(BasicDBList.class, l -> l.add(operatorToMongoKey(entry._1(), entry._2())))
                                .otherwise(() -> {
                                });
                    }, (a, b) -> {
                        a.putAll(b.toMap());
                        return a;
                    }, Characteristics.UNORDERED)));
}

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From source file:com.ikanow.aleph2.shared.crud.mongodb.utils.MongoDbUtils.java

/** Create a MongoDB update object
 * @param update - the generic specification
 * @param add increments numbers or adds to sets/lists
 * @param remove decrements numbers of removes from sets/lists
 * @return the mongodb object/* w  w  w.java 2s .com*/
 * @throws IOException 
 * @throws JsonMappingException 
 * @throws JsonGenerationException 
 */
@SuppressWarnings("unchecked")
public static <O> DBObject createUpdateObject(final UpdateComponent<O> update) {
    final ObjectMapper object_mapper = MongoJackModule
            .configure(BeanTemplateUtils.configureMapper(Optional.empty()));

    return update.getAll().entries().stream()
            .map(kv -> Patterns
                    .match(kv.getValue()._2()).<Map.Entry<String, Tuple2<UpdateOperator, Object>>>andReturn()
                    // Special case, handle bean template
                    .when(e -> null == e, __ -> kv)
                    .when(e -> e instanceof Enum,
                            e -> Maps.immutableEntry(kv.getKey(), Tuples._2T(kv.getValue()._1(), e.toString())))
                    .when(JsonNode.class,
                            j -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(), convertJsonBean(j, object_mapper))))
                    .when(BeanTemplate.class,
                            e -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(), convertBeanTemplate(e, object_mapper))))
                    // Special case, handle list of bean templates
                    .when(Collection.class, l -> !l.isEmpty() && (l.iterator().next() instanceof JsonNode),
                            l -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(),
                                            l.stream().map(j -> convertJsonBean((JsonNode) j, object_mapper))
                                                    .collect(Collectors.toList()))))
                    .when(Collection.class, l -> !l.isEmpty() && (l.iterator().next() instanceof BeanTemplate),
                            l -> Maps.immutableEntry(kv.getKey(), Tuples._2T(kv.getValue()._1(), l.stream()
                                    .map(e -> convertBeanTemplate((BeanTemplate<Object>) e, object_mapper))
                                    .collect(Collectors.toList()))))
                    .otherwise(() -> kv))
            .collect(Collector.of(BasicDBObject::new, (acc, kv) -> {
                Patterns.match(kv.getValue()._2()).andAct()
                        // Delete operator, bunch of things have to happen for safety
                        .when(o -> ((UpdateOperator.unset == kv.getValue()._1()) && kv.getKey().isEmpty()
                                && (null == kv.getValue()._2())), o -> acc.put("$unset", null))
                        //Increment
                        .when(Number.class, n -> (UpdateOperator.increment == kv.getValue()._1()),
                                n -> nestedPut(acc, "$inc", kv.getKey(), n))
                        // Set
                        .when(o -> (UpdateOperator.set == kv.getValue()._1()),
                                o -> nestedPut(acc, "$set", kv.getKey(), o))
                        // Unset
                        .when(o -> (UpdateOperator.unset == kv.getValue()._1()),
                                o -> nestedPut(acc, "$unset", kv.getKey(), 1))
                        // Add items/item to list
                        .when(Collection.class, c -> (UpdateOperator.add == kv.getValue()._1()),
                                c -> nestedPut(acc, "$push", kv.getKey(), new BasicDBObject("$each", c)))
                        .when(o -> (UpdateOperator.add == kv.getValue()._1()),
                                o -> nestedPut(acc, "$push", kv.getKey(), o))
                        // Add item/items to set
                        .when(Collection.class, c -> (UpdateOperator.add_deduplicate == kv.getValue()._1()),
                                c -> nestedPut(acc, "$addToSet", kv.getKey(), new BasicDBObject("$each", c)))
                        .when(o -> (UpdateOperator.add_deduplicate == kv.getValue()._1()),
                                o -> nestedPut(acc, "$addToSet", kv.getKey(), o))
                        // Remove items from list by query
                        .when(QueryComponent.class, q -> (UpdateOperator.remove == kv.getValue()._1()),
                                q -> nestedPut(acc, "$pull", kv.getKey(), convertToMongoQuery(q)._1()))
                        // Remove items/item from list
                        .when(Collection.class, c -> (UpdateOperator.remove == kv.getValue()._1()),
                                c -> nestedPut(acc, "$pullAll", kv.getKey(), c))
                        .when(o -> (UpdateOperator.remove == kv.getValue()._1()),
                                o -> nestedPut(acc, "$pullAll", kv.getKey(), Arrays.asList(o)))
                        .otherwise(() -> {
                        }); // (do nothing)
            }, (a, b) -> {
                a.putAll(b.toMap());
                return a;
            }, Characteristics.UNORDERED));
}

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From source file:com.ikanow.aleph2.data_model.utils.TestCrudUtils.java

/** Create a MongoDB update object
 * @param update - the generic specification
 * @param add increments numbers or adds to sets/lists
 * @param remove decrements numbers of removes from sets/lists
 * @return the mongodb object//from w w w  .ja  va 2 s .c  om
 * @throws IOException 
 * @throws JsonMappingException 
 * @throws JsonGenerationException 
 */
@SuppressWarnings("unchecked")
public static <O> DBObject createUpdateObject(final UpdateComponent<O> update) {
    final ObjectMapper object_mapper = MongoJackModule
            .configure(BeanTemplateUtils.configureMapper(Optional.empty()));

    return update.getAll().entries().stream()
            .map(kv -> Patterns
                    .match(kv.getValue()._2()).<Map.Entry<String, Tuple2<UpdateOperator, Object>>>andReturn()
                    // Special case, handle bean template
                    .when(e -> null == e, __ -> kv)
                    .when(JsonNode.class,
                            j -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(), convertJsonBean(j, object_mapper))))
                    .when(BeanTemplate.class,
                            e -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(), convertBeanTemplate(e, object_mapper))))
                    // Special case, handle list of bean templates
                    .when(Collection.class, l -> !l.isEmpty() && (l.iterator().next() instanceof JsonNode),
                            l -> Maps.immutableEntry(kv.getKey(),
                                    Tuples._2T(kv.getValue()._1(),
                                            l.stream().map(j -> convertJsonBean((JsonNode) j, object_mapper))
                                                    .collect(Collectors.toList()))))
                    .when(Collection.class, l -> !l.isEmpty() && (l.iterator().next() instanceof BeanTemplate),
                            l -> Maps.immutableEntry(kv.getKey(), Tuples._2T(kv.getValue()._1(), l.stream()
                                    .map(e -> convertBeanTemplate((BeanTemplate<Object>) e, object_mapper))
                                    .collect(Collectors.toList()))))
                    .otherwise(() -> kv))
            .collect(Collector.of(BasicDBObject::new, (acc, kv) -> {
                Patterns.match(kv.getValue()._2()).andAct()
                        // Delete operator, bunch of things have to happen for safety
                        .when(o -> ((UpdateOperator.unset == kv.getValue()._1()) && kv.getKey().isEmpty()
                                && (null == kv.getValue()._2())), o -> acc.put("$unset", null))
                        //Increment
                        .when(Number.class, n -> (UpdateOperator.increment == kv.getValue()._1()),
                                n -> nestedPut(acc, "$inc", kv.getKey(), n))
                        // Set
                        .when(o -> (UpdateOperator.set == kv.getValue()._1()),
                                o -> nestedPut(acc, "$set", kv.getKey(), o))
                        // Unset
                        .when(o -> (UpdateOperator.unset == kv.getValue()._1()),
                                o -> nestedPut(acc, "$unset", kv.getKey(), 1))
                        // Add items/item to list
                        .when(Collection.class, c -> (UpdateOperator.add == kv.getValue()._1()),
                                c -> nestedPut(acc, "$push", kv.getKey(), new BasicDBObject("$each", c)))
                        .when(o -> (UpdateOperator.add == kv.getValue()._1()),
                                o -> nestedPut(acc, "$push", kv.getKey(), o))
                        // Add item/items to set
                        .when(Collection.class, c -> (UpdateOperator.add_deduplicate == kv.getValue()._1()),
                                c -> nestedPut(acc, "$addToSet", kv.getKey(), new BasicDBObject("$each", c)))
                        .when(o -> (UpdateOperator.add_deduplicate == kv.getValue()._1()),
                                o -> nestedPut(acc, "$addToSet", kv.getKey(), o))
                        // Remove items from list by query
                        .when(QueryComponent.class, q -> (UpdateOperator.remove == kv.getValue()._1()),
                                q -> nestedPut(acc, "$pull", kv.getKey(), convertToMongoQuery(q)._1()))
                        // Remove items/item from list
                        .when(Collection.class, c -> (UpdateOperator.remove == kv.getValue()._1()),
                                c -> nestedPut(acc, "$pullAll", kv.getKey(), c))
                        .when(o -> (UpdateOperator.remove == kv.getValue()._1()),
                                o -> nestedPut(acc, "$pullAll", kv.getKey(), Arrays.asList(o)))
                        .otherwise(() -> {
                        }); // (do nothing)
            }, (a, b) -> {
                a.putAll(b.toMap());
                return a;
            }, Characteristics.UNORDERED));
}

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From source file:org.briljantframework.data.Collectors.java

public static Collector<Vector, ?, DataFrame> toDataFrame(Supplier<DataFrame.Builder> supplier) {
    return Collector.of(supplier, (DataFrame.Builder acc, Vector record) -> {
        if (acc.columns() > 0 && record.size() != acc.columns()) {
            throw new IllegalStateException("All records must have the same size.");
        } else {/* w w  w  . j  a  v  a  2  s.c om*/
            acc.addRecord(Vectors.transferableBuilder(record));
        }
    }, (DataFrame.Builder left, DataFrame.Builder right) -> {
        if (left.columns() > 0 && left.rows() != right.columns()) {
            throw new IllegalStateException("Columns must all have the same length.");
        } else {
            for (Vector vector : right.build().getRecords()) {
                left.addRecord(Vectors.transferableBuilder(vector));
            }
            return left;
        }
    }, DataFrame.Builder::build);
}

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