Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.Arrays;
import java.util.List;
import java.util.StringJoiner;
import java.util.stream.Collector;

public class Main {

    public static void main(String[] args) throws Exception {
        List<Person> persons = Arrays.asList(new Person("Max", 18), new Person("Peter", 23),
                new Person("Pamela", 23), new Person("David", 12));

        Collector<Person, StringJoiner, String> personNameCollector = Collector.of(() -> {
            System.out.println("supplier");
            return new StringJoiner(" | ");
        }, (j, p) -> {
            System.out.format("accumulator: p=%s; j=%s\n", p, j);
            j.add(p.name.toUpperCase());
        }, (j1, j2) -> {
            System.out.println("merge");
            return j1.merge(j2);
        }, j -> {
            System.out.println("finisher");
            return j.toString();
        });

        String names = persons.stream().collect(personNameCollector);

        System.out.println(names);
    }

}

class Person {
    String name;
    int age;

    Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return name;
    }
}