java.util.stream.Collectors.mapping()方法的使用及代码示例

x33g5p2x  于2022-01-17 转载在 其他  
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本文整理了Java中java.util.stream.Collectors.mapping()方法的一些代码示例，展示了Collectors.mapping()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Collectors.mapping()方法的具体详情如下：
包路径：java.util.stream.Collectors
类名称：Collectors
方法名：mapping

Collectors.mapping介绍

暂无

代码示例

代码示例来源：origin: graphql-java/graphql-java

public static <T, NewKey> Map<NewKey, List<T>> groupingBy(List<T> list, Function<T, NewKey> function) {
  return list.stream().collect(Collectors.groupingBy(function, LinkedHashMap::new, mapping(Function.identity(), Collectors.toList())));
}

代码示例来源：origin: RichardWarburton/java-8-lambdas-exercises

public Map<Artist, List<String>> nameOfAlbums(Stream<Album> albums) {
  return albums.collect(groupingBy(Album::getMainMusician,
                   mapping(Album::getName, toList())));
}
  // END NAME_OF_ALBUMS

代码示例来源：origin: graphql-java/graphql-java

private List<NodeZipper<T>> getDeepestZippers(List<NodeZipper<T>> zippers) {
  Map<Integer, List<NodeZipper<T>>> grouped = zippers
      .stream()
      .collect(groupingBy(astZipper -> astZipper.getBreadcrumbs().size(), LinkedHashMap::new, mapping(Function.identity(), toList())));
  Integer maxLevel = Collections.max(grouped.keySet());
  return grouped.get(maxLevel);
}

代码示例来源：origin: Graylog2/graylog2-server

private TreeMap<DateTime, Long> aggregateToDaily(Map<DateTime, Long> histogram) {
  return histogram.entrySet().stream()
      .collect(Collectors.groupingBy(entry -> entry.getKey().withTimeAtStartOfDay(),
          TreeMap::new,
          Collectors.mapping(Map.Entry::getValue, Collectors.summingLong(Long::valueOf))));
}

代码示例来源：origin: shekhargulati/99-problems

public static <T> Map<Boolean, List<T>> split(List<T> list, int n) {
    return IntStream
        .range(0, list.size())
        .mapToObj(i -> new SimpleEntry<>(i, list.get(i)))
        .collect(partitioningBy(entry -> entry.getKey() < n, mapping(SimpleEntry::getValue, toList())));
  }
}

代码示例来源：origin: graphhopper/graphhopper

Transfers(GTFSFeed feed) {
  this.transfersToStop = feed.transfers.values().stream().collect(Collectors.groupingBy(t -> t.to_stop_id));
  this.transfersFromStop = feed.transfers.values().stream().collect(Collectors.groupingBy(t -> t.from_stop_id));
  this.routesByStop = feed.stop_times.values().stream()
      .collect(Collectors.groupingBy(stopTime -> stopTime.stop_id,
          Collectors.mapping(stopTime -> feed.trips.get(stopTime.trip_id).route_id, Collectors.toSet())));
}

代码示例来源：origin: checkstyle/checkstyle

/**
 * Generate the map of third party Checkstyle module names to the set of their fully qualified
 * names.
 * @param loader the class loader used to load Checkstyle package names
 * @return the map of third party Checkstyle module names to the set of their fully qualified
 *      names
 */
private Map<String, Set<String>> generateThirdPartyNameToFullModuleName(ClassLoader loader) {
  Map<String, Set<String>> returnValue;
  try {
    returnValue = ModuleReflectionUtil.getCheckstyleModules(packages, loader).stream()
      .collect(Collectors.groupingBy(Class::getSimpleName,
        Collectors.mapping(Class::getCanonicalName, Collectors.toSet())));
  }
  catch (IOException ignore) {
    returnValue = Collections.emptyMap();
  }
  return returnValue;
}

代码示例来源：origin: graphhopper/graphhopper

public static Optional<Amount> cheapestFare(Map<String, Fare> fares, Trip trip) {
  return ticketsBruteForce(fares, trip)
      .flatMap(tickets -> tickets.stream()
          .map(ticket -> {
            Fare fare = fares.get(ticket.getFare().fare_id);
            final BigDecimal priceOfOneTicket = BigDecimal.valueOf(fare.fare_attribute.price);
            return new Amount(priceOfOneTicket, fare.fare_attribute.currency_type);
          })
          .collect(Collectors.groupingBy(Amount::getCurrencyType, Collectors.mapping(Amount::getAmount, Collectors.reducing(BigDecimal.ZERO, BigDecimal::add))))
          .entrySet()
          .stream()
          .findFirst() // TODO: Tickets in different currencies for one trip
          .map(e -> new Amount(e.getValue(), e.getKey())));
}

代码示例来源：origin: apache/nifi

public Map<EntityChangeType, List<AtlasEntity>> getChangedFlowPathEntities() {
  // Convert NiFiFlowPath to AtlasEntity.
  final HashMap<EntityChangeType, List<AtlasEntity>> changedPaths = flowPaths.values().stream()
      .map(path -> {
        final EntityChangeType changeType = getFlowPathChangeType(path);
        switch (changeType) {
          case CREATED:
          case UPDATED:
          case AS_IS:
            return toAtlasEntity(changeType, path);
          default:
            return new Tuple<>(changeType, path.getExEntity());
        }
      }).collect(Collectors.groupingBy(Tuple::getKey, HashMap::new, Collectors.mapping(Tuple::getValue, Collectors.toList())));
  updateAudit.add("CREATED NiFiFlowPath=" + changedPaths.get(EntityChangeType.CREATED));
  updateAudit.add("UPDATED NiFiFlowPath=" + changedPaths.get(EntityChangeType.UPDATED));
  updateAudit.add("DELETED NiFiFlowPath=" + changedPaths.get(EntityChangeType.DELETED));
  return changedPaths;
}

代码示例来源：origin: Vedenin/useful-java-links

Map<String, String> groupJoin = strings.stream().collect(Collectors.groupingBy((p) -> p.substring(0, 1), Collectors.mapping((p) -> p.substring(1, 2), Collectors.joining(":"))));
System.out.println("groupJoin = " + groupJoin); // print  groupJoin = groupJoin = {a=1/1, b=2, c=3}

代码示例来源：origin: speedment/speedment

private void joinInMapEntity() {
  ExampleUtil.log("joinInMapEntity");
  Join<Tuple2<Film, Language>> join = joinComponent
    .from(FilmManager.IDENTIFIER)
    .innerJoinOn(Language.LANGUAGE_ID).equal(Film.LANGUAGE_ID)
    .build(Tuples::of);
  Map<Language, List<Film>> languageFilmMap2 = join.stream()
    .collect(
      // Apply this classifier
      groupingBy(Tuple2::get1,
        // Map down-stream elements and collect to a list
        mapping(Tuple2::get0, toList())
      )
    );
  languageFilmMap2.forEach((l, fl)
    -> System.out.format("%s: %s %n", l.getName(), fl.stream().map(Film::getTitle).collect(joining(", ")))
  );
}

代码示例来源：origin: apache/hbase

.filter(l -> !l.getRegion().isOffline()).filter(l -> l.getServerName() != null)
  .collect(Collectors.groupingBy(l -> l.getServerName(),
   Collectors.mapping(l -> l.getRegion(), Collectors.toList())));
List<CompletableFuture<CacheEvictionStats>> futures = new ArrayList<>();
CacheEvictionStatsAggregator aggregator = new CacheEvictionStatsAggregator();

代码示例来源：origin: apache/hbase

/**
 * {@inheritDoc}
 */
@Override
public CacheEvictionStats clearBlockCache(final TableName tableName) throws IOException {
 checkTableExists(tableName);
 CacheEvictionStatsBuilder cacheEvictionStats = CacheEvictionStats.builder();
 List<Pair<RegionInfo, ServerName>> pairs =
  MetaTableAccessor.getTableRegionsAndLocations(connection, tableName);
 Map<ServerName, List<RegionInfo>> regionInfoByServerName =
   pairs.stream()
     .filter(pair -> !(pair.getFirst().isOffline()))
     .filter(pair -> pair.getSecond() != null)
     .collect(Collectors.groupingBy(pair -> pair.getSecond(),
       Collectors.mapping(pair -> pair.getFirst(), Collectors.toList())));
 for (Map.Entry<ServerName, List<RegionInfo>> entry : regionInfoByServerName.entrySet()) {
  CacheEvictionStats stats = clearBlockCache(entry.getKey(), entry.getValue());
  cacheEvictionStats = cacheEvictionStats.append(stats);
  if (stats.getExceptionCount() > 0) {
   for (Map.Entry<byte[], Throwable> exception : stats.getExceptions().entrySet()) {
    LOG.debug("Failed to clear block cache for "
      + Bytes.toStringBinary(exception.getKey())
      + " on " + entry.getKey() + ": ", exception.getValue());
   }
  }
 }
 return cacheEvictionStats.build();
}

代码示例来源：origin: kiegroup/optaplanner

private void writeSectorsView() {
  nextSheet("Sectors view", 1, 2, true);
  String[] filteredConstraintNames = {SECTOR_CONFLICT};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Sector tag");
  writeTimeslotHoursHeaders();
  Map<String, Map<Timeslot, List<Talk>>> tagToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .flatMap(talk -> talk.getSectorTagSet().stream()
          .map(tag -> Pair.of(tag, Pair.of(talk.getTimeslot(), talk))))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<String, Map<Timeslot, List<Talk>>> entry : tagToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(entry.getKey());
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList, filteredConstraintNames);
    }
  }
  autoSizeColumnsWithHeader();
}

代码示例来源：origin: kiegroup/optaplanner

private void writeAudienceTypesView() {
  nextSheet("Audience types view", 1, 2, true);
  String[] filteredConstraintNames = {AUDIENCE_TYPE_DIVERSITY, AUDIENCE_TYPE_THEME_TRACK_CONFLICT};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Audience type");
  writeTimeslotHoursHeaders();
  Map<String, Map<Timeslot, List<Talk>>> audienceTypeToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .flatMap(talk -> talk.getAudienceTypeSet().stream()
          .map(audienceType -> Pair.of(audienceType, Pair.of(talk.getTimeslot(), talk))))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<String, Map<Timeslot, List<Talk>>> entry : audienceTypeToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(entry.getKey());
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList, filteredConstraintNames);
    }
  }
  autoSizeColumnsWithHeader();
}

代码示例来源：origin: kiegroup/optaplanner

private void writeAudienceLevelsView() {
  nextSheet("Audience levels view", 1, 2, true);
  String[] filteredConstraintNames = {AUDIENCE_LEVEL_DIVERSITY, CONTENT_AUDIENCE_LEVEL_FLOW_VIOLATION};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Audience level");
  writeTimeslotHoursHeaders();
  Map<Integer, Map<Timeslot, List<Talk>>> levelToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .map(talk -> Pair.of(talk.getAudienceLevel(), Pair.of(talk.getTimeslot(), talk)))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<Integer, Map<Timeslot, List<Talk>>> entry : levelToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(Integer.toString(entry.getKey()));
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList, filteredConstraintNames);
    }
  }
  autoSizeColumnsWithHeader();
}

代码示例来源：origin: kiegroup/optaplanner

private void writeLanguagesView() {
  nextSheet("Languages view", 1, 2, true);
  String[] filteredConstraintNames = {LANGUAGE_DIVERSITY};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Language");
  writeTimeslotHoursHeaders();
  Map<String, Map<Timeslot, List<Talk>>> languageToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .map(talk -> Pair.of(talk.getLanguage(), Pair.of(talk.getTimeslot(), talk)))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<String, Map<Timeslot, List<Talk>>> entry : languageToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(entry.getKey());
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList, filteredConstraintNames);
    }
  }
  autoSizeColumnsWithHeader();
}

代码示例来源：origin: kiegroup/optaplanner

private void writeThemeTracksView() {
  nextSheet("Theme tracks view", 1, 2, true);
  String[] filteredConstraintNames = {THEME_TRACK_CONFLICT, AUDIENCE_TYPE_THEME_TRACK_CONFLICT, SAME_DAY_TALKS};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Theme track tag");
  writeTimeslotHoursHeaders();
  Map<String, Map<Timeslot, List<Talk>>> tagToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .flatMap(talk -> talk.getThemeTrackTagSet().stream()
          .map(tag -> Pair.of(tag, Pair.of(talk.getTimeslot(), talk))))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<String, Map<Timeslot, List<Talk>>> entry : tagToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(entry.getKey());
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList, filteredConstraintNames);
    }
  }
  autoSizeColumnsWithHeader();
}

代码示例来源：origin: speedment/speedment

.collect(
    mapping(

代码示例来源：origin: kiegroup/optaplanner

private void writeContentsView() {
  nextSheet("Contents view", 1, 2, true);
  String[] filteredConstraintNames = {CONTENT_AUDIENCE_LEVEL_FLOW_VIOLATION, CONTENT_CONFLICT};
  nextRow();
  nextHeaderCell("");
  writeTimeslotDaysHeaders();
  nextRow();
  nextHeaderCell("Content tag");
  writeTimeslotHoursHeaders();
  Map<String, Map<Timeslot, List<Talk>>> tagToTimeslotToTalkListMap = solution.getTalkList().stream()
      .filter(talk -> talk.getTimeslot() != null)
      .flatMap(talk -> talk.getContentTagSet().stream()
          .map(tag -> Pair.of(tag, Pair.of(talk.getTimeslot(), talk))))
      .collect(groupingBy(Pair::getLeft, groupingBy(o -> o.getRight().getLeft(), mapping(o -> o.getRight().getRight(), toList()))));
  for (Map.Entry<String, Map<Timeslot, List<Talk>>> entry : tagToTimeslotToTalkListMap.entrySet()) {
    nextRow();
    nextHeaderCell(entry.getKey());
    Map<Timeslot, List<Talk>> timeslotToTalkListMap = entry.getValue();
    for (Timeslot timeslot : solution.getTimeslotList()) {
      List<Talk> talkList = timeslotToTalkListMap.get(timeslot);
      nextTalkListCell(talkList,
          talk -> talk.getCode() + " (level " + talk.getAudienceLevel() + ")",
          filteredConstraintNames,
          justificationList -> justificationList.stream().allMatch(justification -> !(justification instanceof Talk)
              || ((Talk) justification).getContentTagSet().contains(entry.getKey())
          ));
    }
  }
  autoSizeColumnsWithHeader();
}

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