example_of_cold_observable.java

_log("Before Observable");

// Create a "cold" observable.
Observable<Boolean> ob = Observable
    // The "just" convert a boolean into an Observable.
    .just(true)
    // Transform the items emitted by an Observable by applying a function to each item.
    .map(new Func1<Boolean, Boolean>() {
        @Override
        public Boolean call(Boolean aBoolean) {
            _log("Within Observable");
            _doSomeLongOperation_thatBlocksCurrentThread();
            return aBoolean;
        }
    })
    // Run Observable asynchronously.
    .subscribeOn(Schedulers.io())
    // Emit the items to subscribers on main thread.
    .observeOn(AndroidSchedulers.mainThread());

// Observe and get the subscription (like a voucher).
Subscription subscription = ob
    .subscribe(new Action1<Boolean>() {
        @Override
        public void call(Boolean bool) {
            _log(String.format("Call with return value \"%b\"", bool));
        }
    });

_log("Right after Observable");