Try It Yourself - SyntaxStudy Editor

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import java.util.*;
import java.util.stream.*;

public class StreamBasicsDemo {
    record Person(String name, int age, String city) {}

public static void main(String[] args) {
        List<Person> people = List.of(
            new Person("Alice",  28, "London"),
            new Person("Bob",    35, "Paris"),
            new Person("Carol",  22, "London"),
            new Person("Dave",   31, "Berlin"),
            new Person("Eve",    28, "Paris")
        );

// filter + map + collect to List
        List<String> londonNames = people.stream()
            .filter(p -> p.city().equals("London"))
            .map(Person::name)
            .collect(Collectors.toList());
        System.out.println("London residents: " + londonNames);

// filter + map + sorted + collect
        List<String> youngSorted = people.stream()
            .filter(p -> p.age() < 30)
            .map(p -> p.name() + " (" + p.age() + ")")
            .sorted()
            .collect(Collectors.toList());
        System.out.println("Under 30 sorted:  " + youngSorted);

// Collectors.joining
        String nameList = people.stream()
            .map(Person::name)
            .collect(Collectors.joining(", ", "[", "]"));
        System.out.println("Name list: " + nameList);

// Collectors.groupingBy
        Map<String, List<String>> byCity = people.stream()
            .collect(Collectors.groupingBy(
                Person::city,
                Collectors.mapping(Person::name, Collectors.toList())
            ));
        System.out.println("By city: " + byCity);
    }
}