Test.java

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.CompletableFuture;
import java.util.function.Supplier;

class Test {
    public static void main(String[] args) {
        Supplier<Integer> task1 = () -> {
            // execute a long-running task (just for demo purpose)
            int result = 0;
            for (int i = 0; i < 10000; i++) {
                result = new Random().nextInt(100);
            }
            return result;
        };

        Supplier<List<Integer>> task2 = () -> {
            // execute a long-running task (just for demo purpose)
            List<Integer> result = new ArrayList<>();
            for (int i = 0; i < 10000; i++) {
                result.add(new Random().nextInt(100));
            }
            return result;
        };

        LongRunningTaskService service = new LongRunningTaskService();
        service.executeCompletableFuture(task1).thenAccept(System.out::println);
        service.executeMono(task1).doOnNext(System.out::println).subscribe();
        service.executeFlux(task2).take(3).doOnNext(System.out::println).subscribe();
    }
}