Rxjava schedule wont run after last line

Question

I'm new to RX and i don't know how the schedulers work. below is some code that never run onComplete . but if i put a while(true) loop at the end it works correctly. it seams the app will exit before running new thread.

why is this happening? and how to fix this issue?

Subscriber<String> subscriber = new Subscriber<String>() {
        @Override
        public void onCompleted() {
            System.out.println("done");
        }

        @Override
        public void onError(Throwable throwable) {

        }

        @Override
        public void onNext(String o) {
            System.out.println(o);
        }
    };

    Observable.from(new String[]{"1", "2", "3","4"}).
            subscribeOn(Schedulers.immediate())
            .observeOn(Schedulers.newThread())
            .subscribe(subscriber);

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

Just add Thread.sleep(1000); as the last statement if your program exits too early.

As to why this happens.

This answer quotes:

The Java Virtual Machine continues to execute threads until either of the following occurs:

...

All threads that are not daemon threads have died ...

Now if we look at RxThreadFactory that produces threads for Schedulers:

public final class RxThreadFactory extends AtomicLong implements ThreadFactory {
    
    ...

    @Override
    public Thread newThread(Runnable r) {
        Thread t = new Thread(r, prefix + incrementAndGet());
        t.setDaemon(true);
        return t;
    }
}

So a more complex solution would be to use Schedulers.from() and pass in a custom Executor with your own ThreadFactory that produces non-daemon threads.

thanks! but not looking for just a working solution. looking for the right way. what if `newThread` is gonna take 5 seconds? — , Jan 02 '16 at 09:28

Rxjava schedule wont run after last line

1 Answers1