Example usage for java.util List stream

Introduction

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

Prototype

default Stream<E> stream()

Source Link

Document

Returns a sequential Stream with this collection as its source.

Usage

From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();

    System.out.println("Male members of the collection (bulk data operations):");
    roster.stream().filter(e -> e.getGender() == Person.Sex.MALE).forEach(e -> System.out.println(e.getName()));

}

From source file:Main.java

public static void main(String[] args) {
    Integer[] intArray = { 1, 2, 3, 4, 5, 6, 7, 8 };
    List<Integer> listOfIntegers = new ArrayList<>(Arrays.asList(intArray));

    Comparator<Integer> normal = Integer::compare;
    Comparator<Integer> reversed = normal.reversed();
    Collections.sort(listOfIntegers, reversed);

    listOfIntegers.stream().forEach(e -> System.out.print(e + " "));
    System.out.println("");

}

From source file:Main.java

public static void main(String[] args) throws Exception {

    List<Foo> foos = new ArrayList<>();

    IntStream.range(1, 4).forEach(num -> foos.add(new Foo("Foo" + num)));

    foos.forEach(f -> IntStream.range(1, 4).forEach(num -> f.bars.add(new Bar("Bar" + num + " <- " + f.name))));

    foos.stream().flatMap(f -> f.bars.stream()).forEach(b -> System.out.println(b.name));
}

From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();

    System.out.println("Members by gender:");
    Map<Person.Sex, List<Person>> byGender = roster.stream().collect(Collectors.groupingBy(Person::getGender));

    List<Map.Entry<Person.Sex, List<Person>>> byGenderList = new ArrayList<>(byGender.entrySet());

    byGenderList.stream().forEach(e -> {
        System.out.println("Gender: " + e.getKey());
        e.getValue().stream().map(Person::getName).forEach(f -> System.out.println(f));
    });/*from w  ww  . j a  v  a 2  s.  c  o m*/

}

From source file:Main.java

public static void main(String[] args) {
    List<Trade> trades = TradeUtil.createTrades(100);

    int cpus = Runtime.getRuntime().availableProcessors();
    long start = System.currentTimeMillis();
    trades.stream().parallel().forEach(t -> doSomething(t));
    long end = System.currentTimeMillis();

    System.out.println("Time for parallel op:" + (end - start) / 1000 + "sec on " + cpus);
}

From source file:Main.java

public static void main(String[] argv) {
    List<Person> persons = new ArrayList<>();
    persons.add(new Person("Joe", 12));
    persons.add(new Person("Jim", 34));
    persons.add(new Person("John", 23));

    List<Person> list = persons.stream().filter(p -> p.getAge() > 18).collect(Collectors.toList());
    list.forEach(p -> System.out.println(p.getFirstName()));

}

From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();

    System.out.println("Total age by gender:");
    Map<Person.Sex, Integer> totalAgeByGender = roster.stream().collect(
            Collectors.groupingBy(Person::getGender, Collectors.reducing(0, Person::getAge, Integer::sum)));

    List<Map.Entry<Person.Sex, Integer>> totalAgeByGenderList = new ArrayList<>(totalAgeByGender.entrySet());

    totalAgeByGenderList.stream()//from  ww  w .  j  a  va  2  s.com
            .forEach(e -> System.out.println("Gender: " + e.getKey() + ", Total Age: " + e.getValue()));

}

From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();

    System.out.println("Names by gender:");
    Map<Person.Sex, List<String>> namesByGender = roster.stream().collect(
            Collectors.groupingBy(Person::getGender, Collectors.mapping(Person::getName, Collectors.toList())));

    List<Map.Entry<Person.Sex, List<String>>> namesByGenderList = new ArrayList<>(namesByGender.entrySet());

    namesByGenderList.stream().forEach(e -> {
        System.out.println("Gender: " + e.getKey());
        e.getValue().stream().forEach(f -> System.out.println(f));
    });/* w ww.  j  a v a2  s.  c o  m*/

}

From source file:org.neo4j.nlp.examples.wikipedia.main.java

public static void main(String[] args) throws IOException {
    List<Map<String, Object>> results = getWikipediaArticles();

    results = results.stream().filter(a -> !a.get("title").toString().trim().isEmpty())
            .collect(Collectors.toList());
    //System.out.println(results);
    // Train model
    results.forEach(row -> {/*from  ww w  . j a  va2 s  .  co m*/
        System.out.println("Training on '" + row.get("title").toString() + "'");
        String articleText = getArticleText(row.get("title").toString());
        if (articleText != null) {
            trainOnText(new String[] { (String) articleText }, new String[] { (String) row.get("title") });
        }

    });

    //System.out.println(results);
    //        try {
    //            Thread.sleep(10);
    //        } catch (InterruptedException e) {
    //            e.printStackTrace();
    //        }
}

From source file:Main.java

public static void main(String[] args) {
    Integer[] intArray = { 1, 2, 3, 4, 5, 6, 7, 8 };
    List<Integer> listOfIntegers = new ArrayList<>(Arrays.asList(intArray));

    List<Integer> serialStorage = new ArrayList<>();

    System.out.println("Serial stream:");
    listOfIntegers.stream()

            // Don't do this! It uses a stateful lambda expression. 
            .map(e -> {/*from   w w w  . j  a  v  a2s  .c  o  m*/
                serialStorage.add(e);
                return e;
            })

            .forEachOrdered(e -> System.out.print(e + " "));
    System.out.println("");

    serialStorage.stream().forEachOrdered(e -> System.out.print(e + " "));
    System.out.println("");

    System.out.println("Parallel stream:");
    List<Integer> parallelStorage = Collections.synchronizedList(new ArrayList<>());
    listOfIntegers.parallelStream()

            // Don't do this! It uses a stateful lambda expression.
            .map(e -> {
                parallelStorage.add(e);
                return e;
            })

            .forEachOrdered(e -> System.out.print(e + " "));
    System.out.println("");

    parallelStorage.stream().forEachOrdered(e -> System.out.print(e + " "));
    System.out.println("");

}