Java – Create an Observable from editing text

I’m using android data binding (bind) and I want to create an observable object from editing text data so that I can perform operations on it using rxjava.
Here is my code.

XML

<EditText
            android:id="@+id/edit_text_username"
            android:layout_width="match_parent"
            android:addTextChangedListener="@{viewModel.getUsername}"
            android:background="@drawable/border_edit_top"
            android:drawableLeft="@drawable/ic_person_white_24px"
            android:drawablePadding="10dp"
            android:drawableStart="@drawable/ic_person_white_24px"
            android:hint="@string/username"
            android:inputType="text"
            android:paddingEnd="10dp"
            android:paddingLeft="10dp"
            android:paddingRight="10dp"
            android:paddingStart="10dp"
            app:layout_heightPercent="10%" />

ViewModel class

 public TextWatcher getUsername() {
    return new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

}

@Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            Log.i("username", s.toString());
        }

@Override
        public void afterTextChanged(Editable s) {

}
    };
}

I

have 3 such edit texts on which I want to use rx java’s combinelatest operator for form validation. In this case, how exactly should I implement RX Java?

You can use RxBinding.

//Validate username field
Observable<Boolean> usernameObservable = RxTextView.textChanges(usernameEditText)
                .map(username -> StringUtils.isNotBlank(username) && Validators.validateUsername(username.toString())).skip(1);

Validate password field
Observable<CharSequence> passwordObservable = RxTextView.textChanges(passwordEditText).skip(1);

Validate confirm password field
Observable<CharSequence> confirmPasswordObservable = RxTextView.textChanges(confirmPasswordEditText)
                .skip(1);

Validate password matches field
Observable<Boolean> passwordMatcherObservable = Observable.combineLatest(passwordObservable, confirmPasswordObservable,
                (password, confirmPassword) -> password.toString().equals(confirmPassword.toString())).skip(1);

Observable.combineLatest(passwordMatcherObservable, usernameObservable,
                (passwordMatch, isUsernameValid) -> passwordMatch && isUsernameValid)
                .distinctUntilChanged()
                .subscribe(valid -> createAccountBtn.setEnabled(valid));