Streams

Divisible by 3

long numbersDivisibleByThree = inputs.stream()
    .mapToInt(s -> Integer.valueOf(s))
    .filter(number -> number % 3 == 0)
    .count();

Divisible by 3

long numbersDivisibleByThree = inputs.stream()
    .mapToInt(s -> Integer.valueOf(s))
    .filter(number -> number % 3 == 0)
    .count();

Average

double average = inputs.stream()
    .mapToInt(s -> Integer.valueOf(s))
    .average()
    .getAsDouble();

Filter and create another list with filtered values

ArrayList<Integer> values = list.stream()
    .filter(value -> value > 5)
    .map(value -> value * 2)
    .collect(Collectors.toCollection(ArrayList::new));

Print all values in collections

values.stream()
    .filter(value -> value % 2 == 0)
    .forEach(value -> System.out.println(value));

Filter by lastName in Alphabetical order

        persons.stream()
                .map(person -> person.getLastName())
                .distinct()
                .sorted()
                .forEach(name -> System.out.println(name));

Convert while loop for printing all elements into stream()

    public void printItems() {
//        int indeksi = 0;
//        while (indeksi < this.suitcases.size()) {
//        this.suitcases.get(indeksi).printItems();
//        indeksi++;
//        }
        
        this.suitcases.stream()
                .forEach(suitcase -> suitcase.printItems());
    }

Convert while loop to add all the weights of all elements in a list to a stream() ``` public int totalWeight() { int summa = 0; int indeksi = 0;

// while (indeksi < this.suitcases.size()) { // summa += this.suitcases.get(indeksi).totalWeight(); // indeksi++; // } return this.suitcases.stream() .mapToInt(Suitcase::totalWeight) .sum(); }

**Programm that creates objects with data from file and prints them**

public class BooksFromFile {

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    // test your method here

    readBooks("books.txt").stream()
            .forEach(System.out::println);
}

public static List<Book> readBooks(String file) {
    List<Book> books = new ArrayList<>();
    try {
        Files.lines(Paths.get(file))
                .map(row -> row.split(","))
                .map(parts -> new Book(parts[0], Integer.valueOf(parts[1]), Integer.valueOf(parts[2]), parts[3]))
                .forEach(books::add);
    } catch (IOException e) {
        System.out.println("Error: " + e.getMessage());
    }
    return books;
}

}

**Program that reads data from file, sorts it (alphabetically, by size, etc.) and prints it**

try { Files.lines(Paths.get(“literacy.csv”)) .map(x -> x.split(“,”)) .sorted((x, y) -> x[5].compareTo(y[5])) .forEach(row -> System.out.println(row[3] + ” (” + row[4] + “),” + row[2].split(” “)[1].trim() +”, ” + row[5])); } catch (IOException e) { System.out.println(“Error:” + e.getMessage()); }

**Sorting By Multiple Criteria**
We'll use Java's Comparator class with methods comparing and theComparing. Example <https://github.com/isaac-diez/java_mooc_2/blob/master/part10-Part10_14.Literature/src/main/java/MainProgram.java>

    Comparator<Book> comparator = Comparator
            .comparing(Book::getBookAgeRecommendation)
            .thenComparing(Book::getBookName);

    Collections.sort(books, comparator);

    for (Book b : books) {
        System.out.println(b);
    }

```