ReactiveAndroid

Reactive events and properties with RxJava for Android

Installation

Dependency

• RxJava

Gradle

repositories {
    jcenter()
}

dependencies {
    compile 'com.github.kittinunf.reactiveandroid:reactiveandroid-ui:<latest-version>' //for base UI
    compile 'com.github.kittinunf.reactiveandroid:reactiveandroid-appcompat-v7:<latest-version>' //for appcompat-v7 module
    compile 'com.github.kittinunf.reactiveandroid:reactiveandroid-support-v4:<latest-version>' //for support-v4 module
    compile 'com.github.kittinunf.reactiveandroid:reactiveandroid-design:<latest-version>' //for design support module
}

Why you might need this?

Have you ever wish Android SDK had supported RxJava by default? Well, you have that wish with ReactiveAndroid.

Let's say, you need to observe view being clicked. Yes, you definitely can do it with View.OnClickListener. However, with ReactiveAndroid, you can simply do this:

button.rx.click().subscribe {
    //do something when button is clicked
}

Or, let's assume that you have Observable<String> that wants to be outputted with TextView. You can just do this:

val o = Observable.just("Hello")
o.map { "$it Bob" }.subscribe(textView.rx.text)

From above example, whenever Observable emits next, it will bind with setText(value) of TextView.

In this way, you could construct your logic as Observable in Presenter or ViewModel, then bind it with your view to make it updated.

This makes ReactiveAndroid a powerful tool to perform data binding in your MV* architecture (MVP, MVVM).

Another example is registration form. You probably want to know whether input email & password are valid or not. So that, you could disable/enable button as user types.

val emails = emailEditText.rx.text().map { it.toString() } // becomes Observable<String> for email
val passwords = passwordEditText.rx.text().map { it.toString() } // becomes Observable<String> for password

val emailValids = emails.map { Pattern.matches(EMAIL_PATTERN, it) }
val passwordValids = passwords.map { it.length > PASSWORD_LENGTH }

val emailAndPasswordValids = Observables.combineLatest(emailValids, passwordValids) { user, pass -> user and pass } // becomes Observable<Boolean> for validity

emailAndPasswordValids.bindTo(signInButton.rx.enabled) // bind validity value with button

Sample

There are couple of sample code that take advantage power of ReactiveAndroid. You can checkout in sample folder.

Terminology

We want to be familiar as much as possible to the Android SDK. So that Event and Property from Android elements follow naming convention of Android SDK whenever it can.

Events

Think about listener from Android SDK of your choice, then remove the word "on" and also the word "listener". Then, append that "name" after rx_.

For example,

• View.OnClickListener => view.rx.click()
• RatingBar.OnRatingBarChangeListener => ratingBar.rx_ratingBarChange()
• MenuItem.OnMenuItemClickListener => menuItem.menuItemClick() etc.

Properties

Think about name of property of UI element from Android SDK. Remove {set|get|is|has}. Then, append after rx_ in the similar fashion as Events.

For example,

• View.setEnabled/isEnabled => view.rx.enabled
• DatePicker.setMinDate/getMinDate => datePicker.rx_minDate
• RecyclerView.setHasFixedSize/hasFixedSize => recyclerView.rx_hasFixedSize etc.

Credits

ReactiveAndroid is brought to you by contributors.

Licenses

ReactiveAndroid is released under the MIT license.