Example usage for java.util.stream Collectors toMap

Introduction

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

Prototype

public static <T, K, U, M extends Map<K, U>> Collector<T, ?, M> toMap(
        Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends U> valueMapper,
        BinaryOperator<U> mergeFunction, Supplier<M> mapFactory) 

Source Link

Document

Returns a Collector that accumulates elements into a Map whose keys and values are the result of applying the provided mapping functions to the input elements.

Usage

From source file:Main.java

public static <T, K, U> Collector<T, ?, Map<K, U>> toMap(Function<? super T, ? extends K> keyMapper,
        Function<? super T, ? extends U> valueMapper) {
    return Collectors.toMap(keyMapper, valueMapper, throwingMerger(), HashMap::new);
}

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From source file:Main.java

public static <T, K, U> Collector<T, ?, TreeMap<K, U>> toTreeMap(Function<? super T, ? extends K> keyMapper,
        Function<? super T, ? extends U> valueMapper) {
    return Collectors.toMap(keyMapper, valueMapper, throwingMerger(), TreeMap::new);
}

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From source file:Main.java

public static <T, K, U> Collector<T, ?, LinkedHashMap<K, U>> toLinkedHashMap(
        Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends U> valueMapper) {
    return Collectors.toMap(keyMapper, valueMapper, (u, v) -> {
        throw new IllegalStateException(String.format("Duplicate key %s", u));
    }, LinkedHashMap::new);
}

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From source file:Main.java

public static <T, K, M extends Map<K, T>> M toMap(Collection<T> entities, Function<T, K> keyMapper,
        Supplier<M> supplier) {
    return entities.stream().collect(Collectors.toMap(keyMapper, Function.identity(), (a, b) -> b, supplier));
}

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From source file:com.thoughtworks.go.agent.common.util.HeaderUtil.java

public static Map<String, String> parseExtraProperties(Header extraPropertiesHeader) {
    if (extraPropertiesHeader == null || StringUtils.isBlank(extraPropertiesHeader.getValue())) {
        return new HashMap<>();
    }/*from ww  w  .j a v a  2 s  .c om*/

    try {
        final String headerValue = new String(Base64.decodeBase64(extraPropertiesHeader.getValue()), UTF_8);

        if (StringUtils.isBlank(headerValue)) {
            return new HashMap<>();
        }

        return Arrays.stream(headerValue.trim().split(" +")).map(property -> property.split("="))
                .collect(Collectors.toMap(keyAndValue -> keyAndValue[0].replaceAll("%20", " "),
                        keyAndValue -> keyAndValue[1].replaceAll("%20", " "), (value1, value2) -> value1,
                        LinkedHashMap::new));
    } catch (Exception e) {
        LOGGER.warn("Failed to parse extra properties header value: {}", extraPropertiesHeader.getValue(), e);
        return new HashMap<>();
    }
}

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From source file:Main.java

public static <T, K, V, M extends Map<K, V>> M toMap(Collection<T> entities, Function<T, K> keyMapper,
        Function<T, V> valueMapper, Supplier<M> supplier) {
    return entities.stream().collect(Collectors.toMap(keyMapper, valueMapper, (a, b) -> b, supplier));
}

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From source file:com.thinkbiganalytics.discovery.parsers.csv.CSVAutoDetect.java

private static <K, V extends Comparable<? super V>> Map<K, V> sortMapByValue(Map<K, V> map) {
    return map.entrySet().stream().sorted(Map.Entry.comparingByValue(Collections.reverseOrder())).collect(
            Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));
}

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From source file:cn.edu.zjnu.acm.judge.service.LanguageService.java

public Map<Integer, Language> getAvailableLanguages() {
    return languageMapper.findAll().stream().collect(
            Collectors.toMap(Language::getId, Function.identity(), throwOnMerge(), LinkedHashMap::new));
}

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From source file:com.intuit.quickbase.MergeStatService.java

public void retrieveCountryPopulationList() {

    DBStatService dbStatService = new DBStatService();
    List<Pair<String, Integer>> dbList = dbStatService.GetCountryPopulations();

    ConcreteStatService conStatService = new ConcreteStatService();
    List<Pair<String, Integer>> apiList = conStatService.GetCountryPopulations();

    //Use of Predicate Interface
    Predicate<Pair<String, Integer>> pred = (pair) -> pair != null;

    if (apiList != null) {
        // Converting the keys of each element in the API list to lowercase
        List<Pair<String, Integer>> modifiedAPIList = apiList.stream().filter(pred)
                .map(p -> new ImmutablePair<String, Integer>(p.getKey().toLowerCase(), p.getValue()))
                .collect(Collectors.toList());
        //modifiedAPIList.forEach(pair -> System.out.println("key: " + pair.getLeft() + ": value: " + pair.getRight()));                      

        if (dbList != null) {
            // Merge two list and remove duplicates
            Collection<Pair<String, Integer>> result = Stream.concat(dbList.stream(), modifiedAPIList.stream())
                    .filter(pred)/*from   w  ww  . ja va2s. c o  m*/
                    .collect(Collectors.toMap(Pair::getLeft, p -> p, (p, q) -> p, LinkedHashMap::new)).values();

            // Need to Convert collection to List
            List<Pair<String, Integer>> merge = new ArrayList<>(result);
            merge.forEach(pair -> System.out.println("key: " + pair.getKey() + ": value: " + pair.getValue()));

        } else {
            System.out.println("Country list retrieved form database is empty");
        }
    } else {
        System.out.println("Country list retrieved form API is empty");
    }

    //            if(apiList != null) {
    //                Iterator itr = apiList.iterator();
    //                for(Pair<String, Integer> pair : apiList){                    
    //                    //System.out.println("key: " + pair.getLeft() + ": value: " + pair.getRight());
    //                }                
    //            }    

}

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From source file:org.fede.calculator.config.AppConfig.java

public static <K, U> Collector<Map.Entry<K, U>, ?, Map<K, U>> entriesToLinkedHashMap() {
    return Collectors.toMap((e) -> e.getKey(), (e) -> e.getValue(), (v1, v2) -> v1, LinkedHashMap::new);
}

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