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<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8);
    List<Integer> twoEvenSquares = numbers.stream().filter(n -> n % 2 == 0).map(n -> n * n).limit(2)
            .collect(toList());/*from  w  w  w.ja  v a2 s.  c  om*/

    System.out.println(twoEvenSquares);
}

From source file:Main.java

public static void main(String[] args) {
    List<Integer> _numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    Iterator<Integer> iter = _numbers.stream().filter(value -> value % 2 == 0).iterator();

    while (iter.hasNext()) {
        System.out.println(iter.next());
    }//from ww  w . ja va2  s .co m
}

From source file:Main.java

public static void main(String[] args) {
    List<String> names = Arrays.asList("Chris", "HTML", "XML", "CSS", "");

    Stream<String> s = names.stream();

    Predicate<String> isEmpty = String::isEmpty;
    Predicate<String> notEmpty = isEmpty.negate();

    System.out.println(s.filter(notEmpty).collect(Collectors.toList()));
}

From source file:Main.java

public static void main(String[] args) {
    List<Employee> persons = Employee.persons();
    String names = persons.stream().map(Employee::getName).collect(Collectors.joining());

    String delimitedNames = persons.stream().map(Employee::getName).collect(Collectors.joining(", "));

    String prefixedNames = persons.stream().map(Employee::getName)
            .collect(Collectors.joining(", ", "Hello ", ".  Goodbye."));

    System.out.println("Joined names:  " + names);
    System.out.println("Joined,  delimited names:  " + delimitedNames);
    System.out.println(prefixedNames);
}

From source file:Main.java

public static void main(String[] args) {
    List<String> names = Arrays.asList("XML", "HTML", "Java", "Javascript", "CSS", "Static");

    Optional<String> firstS = names.stream().filter(name -> name.startsWith("S")).findFirst();
    System.out.println(firstS.orElse("None found"));
}

From source file:Main.java

public static void main(String[] args) {
    List<String> _names = Arrays.asList("Bob", "Tom", "Jeff", "Scott", "Jennifer", "Steve");

    List<String> greetings = _names.stream().map(name -> "Hello " + name).collect(Collectors.toList());
    System.out.println(greetings);

}

From source file:Main.java

public static void main(String[] argv) {
    List<String> mascots = new ArrayList<>();
    mascots.add("duke");
    mascots.add("juggy");

    String actual = mascots.stream().reduce((t, u) -> t + "," + u).get();
    System.out.println(actual);//from   w  w w.  ja  v  a  2s.  c o m
}

From source file:Main.java

public static void main(String[] args) {

    List<String> names = Arrays.asList("HTML", "CSS", "CSS3", "Java", "SQL", "Javascript", "MySQL");

    String name5 = names.stream().map(s -> s.toUpperCase()).filter(s -> s.length() < 5)
            .sorted((a, b) -> b.length() - a.length()).findFirst().orElse("a");
    System.out.println(name5);/*from   www  .ja  v  a2s .c  o  m*/

    String name2 = names.stream().map(s -> s.toUpperCase()).filter(s -> s.length() < 2)
            .sorted((a, b) -> b.length() - a.length()).findFirst().orElse("Somthing else");
    System.out.println(name2);
}

From source file:Main.java

public static void main(String[] args) {
    List<String> names = Arrays.asList("XML", "HTML", "Java", "Javascript", "CSS", "Static");

    Optional<String> firstZ = names.stream().filter(name -> name.startsWith("Z")).findFirst();
    if (firstZ.isPresent()) {
        System.out.println(firstZ.get());
    } else {/*  ww  w  . j  a  v a 2s  .c  o  m*/
        System.out.println("No Z's found");
    }
}

From source file:Main.java

public static void main(String[] args) {
    List<Integer> numbers = new ArrayList<Integer>();

    for (Integer i : Arrays.asList(0, 1, 2, 3, 4, 5, 6, 7))
        numbers.add(i);//from w  w w  . j  a v a2s.  c o m
    printList(numbers); // 0,1,2,3,4,5,6,7

    // replaces each element with twice its value
    for (int index = 0; index < numbers.size(); index++) {
        numbers.set(index, numbers.get(index) * 2);
    }
    printList(numbers);

    // does nothing because list is not being changed
    for (Integer number : numbers) {
        number++;
    }
    printList(numbers);

    // same as above -- just different syntax
    for (Iterator<Integer> iter = numbers.iterator(); iter.hasNext();) {
        Integer number = iter.next();
        number++;
    }
    printList(numbers);

    for (ListIterator<Integer> iter = numbers.listIterator(); iter.hasNext();) {
        Integer number = iter.next();
        iter.add(number + 1);
    }
    printList(numbers);

    for (Iterator<Integer> iter = numbers.iterator(); iter.hasNext();) {
        Integer number = iter.next();
        if (number % 2 == 0) // if number is even
            iter.remove(); // remove it from the collection
    }
    printList(numbers); // 1,3,5,7,9,11,13,15

    // ListIterator<?> has a "set" method to replace elements
    for (ListIterator<Integer> iter = numbers.listIterator(); iter.hasNext();) {
        Integer number = iter.next();
        iter.set(number / 2); // divide each element by 2
    }
    printList(numbers); // 0,1,2,3,4,5,6,7

    // Use Java 8 Lambda
    List<Integer> list = numbers;
    list.stream().forEach(elem -> System.out.println("element " + elem));

}