Spring Reactor.java

/* Synchronously prints 
main
Current thread: main
hello, world!
Current thread: main
hello
Current thread: main
world
In about 15 seconds */


@Override
public void run(String... args) throws Exception {
    // Check Hooks.
    System.out.println(Thread.currentThread().getName());
    Mono<String> helloWorld = Mono.just("hello, world!");
    helloWorld.subscribe((x) -> {
        this.printStringWithTimeout(x, 5000);
    });

    Flux<String> fluxHelloWorld = Flux.just("hello", "world");
    fluxHelloWorld.subscribe((x) -> {
        this.printStringWithTimeout(x, 5000);
    });
}

public void printStringWithTimeout(String string, long timeoutMs) {
    try {
        Thread.sleep(5000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println("Current thread: " + Thread.currentThread().getName());
    System.out.println(string);
}