Example usage for java.util Map computeIfAbsent

Introduction

In this page you can find the example usage for java.util Map computeIfAbsent.

Prototype

default V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) 

Source Link

Document

If the specified key is not already associated with a value (or is mapped to null ), attempts to compute its value using the given mapping function and enters it into this map unless null .

Usage

From source file:Main.java

public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();

    for (int i = 0; i < 10; i++) {
        map.putIfAbsent(i, "val" + i);
    }//from w w w.jav  a 2s.  c om

    map.forEach((id, val) -> System.out.println(val));

    map.computeIfPresent(3, (num, val) -> val + num);
    System.out.println(map.get(3)); // val33

    map.computeIfPresent(9, (num, val) -> null);
    System.out.println(map.containsKey(9)); // false

    map.computeIfAbsent(23, num -> "val" + num);
    System.out.println(map.containsKey(23)); // true

    map.computeIfAbsent(3, num -> "bam");
    System.out.println(map.get(3)); // val33
}

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From source file:Main.java

/**
 * Adds the value to map. If the key does not exists new value set is created and the value is added to it. The
 * method ignores null values//from   w w  w  .j ava2  s . com
 *
 * @param <K>
 *            the key type
 * @param <V>
 *            the value type
 * @param map
 *            the map
 * @param key
 *            the key
 * @param newValue
 *            the new value
 */
public static <K, V> void addValueToSetMap(Map<K, Set<V>> map, K key, V newValue) {
    if (newValue == null) {
        return;
    }
    map.computeIfAbsent(key, k -> new LinkedHashSet<>()).add(newValue);
}

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From source file:Main.java

/**
 * Add a value to a map collection, initializing the key's collection if needed
 *
 * @param key Key whose value collection should be added to
 * @param valueToAdd Vale to add to the key's collection
 * @param map Map holding collections//from   w ww .  j  a  v  a  2 s.co  m
 */
public static <K, V> void addToCollectionMap(K key, V valueToAdd, Map<K, Collection<V>> map) {
    if (key != null && valueToAdd != null && map != null) {
        map.computeIfAbsent(key, k -> Lists.newArrayList()).add(valueToAdd);
    }
}

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From source file:Main.java

public static <T, K> Map<K, List<T>> groupBy(List<T> elements, Function<T, K> classifier) {
    Map<K, List<T>> result = new HashMap<>();
    for (T element : elements) {
        K key = classifier.apply(element);
        result.computeIfAbsent(key, e -> new ArrayList<>()).add(element);
    }/*  ww w  . j a  v  a 2 s .  c o  m*/

    return result;
}

---

From source file:Main.java

protected static <T, K, V> void groupToMap(Map<K, List<V>> map, Collection<T> collection,
        Function<T, K> keyFunc, Function<T, V> valueFunc) {
    for (T t : collection) {
        K key = keyFunc.apply(t);//w  w  w . j  a  va 2s  .  c  o  m
        List<V> list = map.computeIfAbsent(key, k -> new ArrayList<>());
        list.add(valueFunc.apply(t));
    }
}

---

From source file:io.servicecomb.foundation.common.net.URIEndpointObject.java

public static Map<String, List<String>> splitQuery(URI uri) {
    final Map<String, List<String>> queryPairs = new LinkedHashMap<String, List<String>>();
    List<NameValuePair> pairs = URLEncodedUtils.parse(uri, StandardCharsets.UTF_8.name());
    for (NameValuePair pair : pairs) {
        List<String> list = queryPairs.computeIfAbsent(pair.getName(), name -> {
            return new ArrayList<>();
        });/* w  ww  .j  ava 2  s  .  com*/
        list.add(pair.getValue());
    }
    return queryPairs;
}

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From source file:com.linecorp.armeria.server.docs.Specification.java

static Specification forServiceConfigs(Iterable<ServiceConfig> serviceConfigs,
        Map<Class<?>, ? extends TBase<?, ?>> sampleRequests) {

    final Map<Class<?>, Iterable<EndpointInfo>> map = new LinkedHashMap<>();

    for (ServiceConfig c : serviceConfigs) {
        c.service().as(ThriftService.class).ifPresent(service -> {
            for (Class<?> iface : service.interfaces()) {
                final Class<?> serviceClass = iface.getEnclosingClass();
                final List<EndpointInfo> endpoints = (List<EndpointInfo>) map.computeIfAbsent(serviceClass,
                        cls -> new ArrayList<>());

                c.pathMapping().exactPath()
                        .ifPresent(p -> endpoints.add(EndpointInfo.of(c.virtualHost().hostnamePattern(), p,
                                service.defaultSerializationFormat(), service.allowedSerializationFormats())));
            }/*from   w  w w  .  java  2 s .  c  om*/
        });
    }

    return forServiceClasses(map, sampleRequests);
}

---

From source file:com.evolveum.midpoint.schema.SelectorOptions.java

public static <T> Map<T, Collection<ItemPath>> extractOptionValues(
        Collection<SelectorOptions<GetOperationOptions>> options, Function<GetOperationOptions, T> supplier) {
    Map<T, Collection<ItemPath>> rv = new HashMap<>();
    for (SelectorOptions<GetOperationOptions> selectorOption : CollectionUtils.emptyIfNull(options)) {
        T value = supplier.apply(selectorOption.getOptions());
        if (value != null) {
            Collection<ItemPath> itemPaths = rv.computeIfAbsent(value, t -> new HashSet<>());
            itemPaths.add(selectorOption.getItemPath());
        }// w w  w.  jav a  2 s  .  co  m
    }
    return rv;
}

---

From source file:com.liferay.apio.architect.internal.body.MultipartToBodyConverter.java

/**
 * Reads a {@code "multipart/form"} HTTP request body into a {@link Body}
 * instance or fails with a {@link BadRequestException} if the input is not
 * a valid multipart form./*w ww .java  2 s  .  com*/
 *
 * @review
 */
public static Body multipartToBody(HttpServletRequest request) {
    if (!isMultipartContent(request)) {
        throw new BadRequestException("Request body is not a valid multipart form");
    }

    FileItemFactory fileItemFactory = new DiskFileItemFactory();

    ServletFileUpload servletFileUpload = new ServletFileUpload(fileItemFactory);

    try {
        List<FileItem> fileItems = servletFileUpload.parseRequest(request);

        Iterator<FileItem> iterator = fileItems.iterator();

        Map<String, String> values = new HashMap<>();
        Map<String, BinaryFile> binaryFiles = new HashMap<>();
        Map<String, Map<Integer, String>> indexedValueLists = new HashMap<>();
        Map<String, Map<Integer, BinaryFile>> indexedFileLists = new HashMap<>();

        while (iterator.hasNext()) {
            FileItem fileItem = iterator.next();

            String name = fileItem.getFieldName();

            Matcher matcher = _arrayPattern.matcher(name);

            if (matcher.matches()) {
                int index = Integer.parseInt(matcher.group(2));

                String actualName = matcher.group(1);

                _storeFileItem(fileItem, value -> {
                    Map<Integer, String> indexedMap = indexedValueLists.computeIfAbsent(actualName,
                            __ -> new HashMap<>());

                    indexedMap.put(index, value);
                }, binaryFile -> {
                    Map<Integer, BinaryFile> indexedMap = indexedFileLists.computeIfAbsent(actualName,
                            __ -> new HashMap<>());

                    indexedMap.put(index, binaryFile);
                });
            } else {
                _storeFileItem(fileItem, value -> values.put(name, value),
                        binaryFile -> binaryFiles.put(name, binaryFile));
            }
        }

        Map<String, List<String>> valueLists = _flattenMap(indexedValueLists);

        Map<String, List<BinaryFile>> fileLists = _flattenMap(indexedFileLists);

        return Body.create(key -> Optional.ofNullable(values.get(key)),
                key -> Optional.ofNullable(valueLists.get(key)), key -> Optional.ofNullable(fileLists.get(key)),
                key -> Optional.ofNullable(binaryFiles.get(key)));
    } catch (FileUploadException | IndexOutOfBoundsException | NumberFormatException e) {

        throw new BadRequestException("Request body is not a valid multipart form", e);
    }
}

---

From source file:com.github.aptd.simulation.datamodel.CXMLReader.java

/**
 * create the station list/*from   ww  w. j  a  v  a2s  .  c  om*/
 *
 * @param p_network network component
 * @param p_agents map with agent asl scripts
 * @param p_factory factory
 * @param p_time time reference
 * @param p_platforms map with already generated platforms
 * @return unmodifyable map with stations
 */
private static Map<String, IStation<?>> station(final Network p_network, final Map<String, String> p_agents,
        final IFactory p_factory, final ITime p_time, final Map<String, IPlatform<?>> p_platforms) {
    final Map<String, IElement.IGenerator<IStation<?>>> l_generators = new ConcurrentHashMap<>();
    final Set<IAction> l_actions = CCommon.actionsFromPackage().collect(Collectors.toSet());
    final ListMultimap<String, IPlatform<?>> l_platformbystationid = Multimaps.index(p_platforms.values(),
            IPlatform::stationid);
    return Collections.<String, IStation<?>>unmodifiableMap(p_network
            .getInfrastructure().getOperationControlPoints().getOcp().parallelStream().filter(
                    i -> hasagentname(i.getAny()))
            .map(i -> agentname(i, i.getAny()))
            .map(i -> l_generators
                    .computeIfAbsent(i.getRight(),
                            a -> stationgenerator(p_factory, p_agents.get(i.getRight()), l_actions, p_time))
                    .generatesingle(i.getLeft().getId(), i.getLeft().getGeoCoord().getCoord().get(0),
                            i.getLeft().getGeoCoord().getCoord().get(1),
                            l_platformbystationid.get(i.getLeft().getId())))
            .collect(Collectors.toMap(IElement::id, i -> i)));
}

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