SignInFieldsSubscription

SignInFieldsSubscription.java

Subscription signInFieldsSubscription = 
  Observable.combineLatest(emailChangeObservable, passwordChangeObservable, 
    new Func2<CharSequence, CharSequence, Boolean>() {
      @Override
      public Boolean call(CharSequence email, CharSequence password) {
          boolean isEmailValid = validateEmail(email.toString());
          boolean isPasswordValid = validatePassword(password.toString());

          return isEmailValid && isPasswordValid;
      }
    }).observeOn(AndroidSchedulers.mainThread()) // UI Thread
      .subscribe(new Observer<Boolean>() {
          @Override
          public void onCompleted() {

          }

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

          @Override
          public void onNext(Boolean validFields) {
              if (validFields) {
                  enableSignIn();
              } else {
                  disableSignIn();
              }
          }
      });