Example usage for java.util.stream Collectors groupingBy

Introduction

In this page you can find the example usage for java.util.stream Collectors groupingBy.

Prototype

public static <T, K, D, A, M extends Map<K, D>> Collector<T, ?, M> groupingBy(
        Function<? super T, ? extends K> classifier, Supplier<M> mapFactory,
        Collector<? super T, A, D> downstream) 

Source Link

Document

Returns a Collector implementing a cascaded "group by" operation on input elements of type T , grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream Collector .

Usage

From source file:Main.java

public static <T, K, V> HashMap<K, HashSet<V>> group(Collection<T> entities, Function<T, K> keyMapper,
        Function<T, V> valueMapper) {
    return entities.stream().collect(Collectors.groupingBy(keyMapper, HashMap::new,
            Collectors.mapping(valueMapper, Collectors.toCollection(HashSet::new))));
}

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From source file:com.mgmtp.perfload.perfalyzer.reporting.ReportCreator.java

public void createReport(final List<PerfAlyzerFile> files) throws IOException {
    Function<PerfAlyzerFile, String> classifier = perfAlyzerFile -> {
        String marker = perfAlyzerFile.getMarker();
        return marker == null ? "Overall" : marker;
    };//from ww w  . j  a  va2  s . c  om
    Supplier<Map<String, List<PerfAlyzerFile>>> mapFactory = () -> new TreeMap<>(Ordering.explicit(tabNames));

    Map<String, List<PerfAlyzerFile>> filesByMarker = files.stream()
            .collect(Collectors.groupingBy(classifier, mapFactory, toList()));

    Map<String, SortedSetMultimap<String, PerfAlyzerFile>> contentItemFiles = new LinkedHashMap<>();

    for (Entry<String, List<PerfAlyzerFile>> entry : filesByMarker.entrySet()) {
        SortedSetMultimap<String, PerfAlyzerFile> contentItemFilesByMarker = contentItemFiles.computeIfAbsent(
                entry.getKey(),
                s -> TreeMultimap.create(new ItemComparator(reportContentsConfigMap.get("priorities")),
                        Ordering.natural()));

        for (PerfAlyzerFile perfAlyzerFile : entry.getValue()) {
            File file = perfAlyzerFile.getFile();
            String groupKey = removeExtension(file.getPath());
            boolean excluded = false;
            for (Pattern pattern : reportContentsConfigMap.get("exclusions")) {
                Matcher matcher = pattern.matcher(groupKey);
                if (matcher.matches()) {
                    excluded = true;
                    log.debug("Excluded from report: {}", groupKey);
                    break;
                }
            }
            if (!excluded) {
                contentItemFilesByMarker.put(groupKey, perfAlyzerFile);
            }
        }
    }

    // explicitly copy it because it is otherwise filtered from the report in order to only show in the overview
    String loadProfilePlot = new File("console", "[loadprofile].png").getPath();
    copyFile(new File(soureDir, loadProfilePlot), new File(destDir, loadProfilePlot));

    Map<String, List<ContentItem>> tabItems = new LinkedHashMap<>();
    Map<String, QuickJump> quickJumps = new HashMap<>();
    Set<String> tabNames = contentItemFiles.keySet();

    for (Entry<String, SortedSetMultimap<String, PerfAlyzerFile>> tabEntry : contentItemFiles.entrySet()) {
        String tab = tabEntry.getKey();
        SortedSetMultimap<String, PerfAlyzerFile> filesForTab = tabEntry.getValue();

        List<ContentItem> contentItems = tabItems.computeIfAbsent(tab, list -> new ArrayList<>());
        Map<String, String> quickJumpMap = new LinkedHashMap<>();
        quickJumps.put(tab, new QuickJump(tab, quickJumpMap));

        int itemIndex = 0;
        for (Entry<String, Collection<PerfAlyzerFile>> itemEntry : filesForTab.asMap().entrySet()) {
            String title = itemEntry.getKey();
            Collection<PerfAlyzerFile> itemFiles = itemEntry.getValue();

            TableData tableData = null;
            String plotSrc = null;
            for (PerfAlyzerFile file : itemFiles) {
                if ("png".equals(getExtension(file.getFile().getName()))) {
                    plotSrc = file.getFile().getPath();
                    copyFile(new File(soureDir, plotSrc), new File(destDir, plotSrc));
                } else {
                    tableData = createTableData(file.getFile());
                }
            }

            // strip off potential marker
            title = substringBefore(title, "{");

            String[] titleParts = split(title, SystemUtils.FILE_SEPARATOR);
            StringBuilder sb = new StringBuilder(50);
            String separator = " - ";
            sb.append(resourceBundle.getString(titleParts[0]));
            sb.append(separator);
            sb.append(resourceBundle.getString(titleParts[1]));

            List<String> fileNameParts = extractFileNameParts(titleParts[1], true);
            if (titleParts[1].contains("[distribution]")) {
                String operation = fileNameParts.get(1);
                sb.append(separator);
                sb.append(operation);
            } else if ("comparison".equals(titleParts[0])) {
                String operation = fileNameParts.get(1);
                sb.append(separator);
                sb.append(operation);
            } else if (titleParts[1].contains("[gclog]")) {
                if (fileNameParts.size() > 1) {
                    sb.append(separator);
                    sb.append(fileNameParts.get(1));
                }
            }

            title = sb.toString();
            ContentItem item = new ContentItem(tab, itemIndex, title, tableData, plotSrc,
                    resourceBundle.getString("report.topLink"));
            contentItems.add(item);

            quickJumpMap.put(tab + "_" + itemIndex, title);
            itemIndex++;
        }
    }

    NavBar navBar = new NavBar(tabNames, quickJumps);
    String testName = removeExtension(testMetadata.getTestPlanFile());
    OverviewItem overviewItem = new OverviewItem(testMetadata, resourceBundle, locale);
    Content content = new Content(tabItems);

    String perfAlyzerVersion;
    try {
        perfAlyzerVersion = Resources.toString(Resources.getResource("perfAlyzer.version"), Charsets.UTF_8);
    } catch (IOException ex) {
        log.error("Could not read perfAlyzer version from classpath resource 'perfAlyzer.version'", ex);
        perfAlyzerVersion = "";
    }

    String dateTimeString = DateTimeFormatter.ISO_OFFSET_DATE_TIME.withLocale(locale)
            .format(ZonedDateTime.now());
    String createdString = String.format(resourceBundle.getString("footer.created"), perfAlyzerVersion,
            dateTimeString);
    HtmlSkeleton html = new HtmlSkeleton(testName, createdString, navBar, overviewItem, content);
    writeReport(html);
}

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