ButtonSubmitValidation.java

Observable<Boolean> emptyFieldStream = Observable.combineLatest(
                RxTextView.textChanges(etEmail)
                        .map(new Func1<CharSequence, Boolean>() {
                            @Override
                            public Boolean call(CharSequence charSequence) {
                                return TextUtils.isEmpty(charSequence);
                            }
                        }),
                RxTextView.textChanges(etPassword)
                        .map(new Func1<CharSequence, Boolean>() {
                            @Override
                            public Boolean call(CharSequence charSequence) {
                                return TextUtils.isEmpty(charSequence);
                            }
                        }),
                RxTextView.textChanges(etPasswordConfirmation)
                        .map(new Func1<CharSequence, Boolean>() {
                            @Override
                            public Boolean call(CharSequence charSequence) {
                                return TextUtils.isEmpty(charSequence);
                            }
                        }),
                new Func3<Boolean, Boolean, Boolean, Boolean>() {
                    @Override
                    public Boolean call(Boolean emailEmpty, Boolean passwordEmpty, Boolean passwordConfirmationEmpty) {
                        return emailEmpty || passwordEmpty || passwordConfirmationEmpty;
                    }
                }
        );

Observable<Boolean> invalidFieldsStream = Observable.combineLatest(
        emailStream,
        passwordStream,
        passwordConfirmationStream,
        emptyFieldStream, new Func4<Boolean, Boolean, Boolean, Boolean, Boolean>() {
    @Override
    public Boolean call(Boolean emailInvalid, Boolean passwordInvalid, Boolean passwordConfirmationInvalid, Boolean emptyFieldExist) {
        return !emailInvalid && !passwordInvalid && !passwordConfirmationInvalid && !emptyFieldExist;
    }
});
        
Observer<Boolean> invalidFieldsObserver = new Observer<Boolean>() {
    @Override
    public void onCompleted() {
        Log.d("rx","All field valid stream completed");
    }

    @Override
    public void onError(Throwable e) {
        Log.d("rx",e.getMessage());
    }

    @Override
    public void onNext(Boolean invalidFieldExist) {
        Log.d("invalidFieldsStream",String.valueOf(invalidFieldExist.booleanValue()));
        btnSubmit.setEnabled(invalidFieldExist);
    }
};
        
invalidFieldsStream.subscribe(invalidFieldsObserver);