RxJava。如何让可观察计时器在后台运行？

import io.reactivex.Observable;
import io.reactivex.schedulers.Schedulers;
import java.util.concurrent.TimeUnit;

public class TimerExample {
    public static void main(String[] args) {
        Observable.interval(1, TimeUnit.SECONDS)
                .observeOn(Schedulers.io()) // 使用Schedulers.io()调度器
                .subscribe(time -> {
                    System.out.println("当前时间：" + time);
                });

        try {
            Thread.sleep(5000); // 主线程休眠5秒，等待计时器输出
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}