EmailChangeObservable

EmailSubscription.java

Subscription emailSubscription = 
  emailChangeObservable
    .doOnNext(new Action1<CharSequence>() {
        @Override
        public void call(CharSequence charSequence) {
            hideEmailError();
        }
    })
    .debounce(400, TimeUnit.MILLISECONDS)
    .filter(new Func1<CharSequence, Boolean>() {
        @Override
        public Boolean call(CharSequence charSequence) {
            return !TextUtils.isEmpty(charSequence);
        }
    })
    .observeOn(AndroidSchedulers.mainThread()) // UI Thread
    .subscribe(new Subscriber<CharSequence>() {
        @Override
        public void onCompleted() {

        }

        @Override
        public void onError(Throwable e) {
            e.printStackTrace();
        }

        @Override
        public void onNext(CharSequence charSequence) {
            boolean isEmailValid = validateEmail(charSequence.toString());
            if (!isEmailValid) {
                showEmailError();
            } else {
                hideEmailError();
            }
        }
    });