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I'm trying to adopt reactive observer pattern in my project and came across RxBinding library. Some claim the benefits of reactive UI implementation pattern as the following:

  • Less boilerplate code
  • Consistent pattern
  • And a more readable code

But I was wondering if there are any other benefits like a more fluid UI, better performance, or less memory usage, etc... that the potential end-user or the device running the software might possibly thank you for? rather than the benefits mentioned above which all seem to cater to the developers.

More importantly are there any drawbacks to this pattern?

And since I'm a Kotlin fan, is there any other way we could get the same benefits utilizing Kotlin language features or Android KTX?

Sources:

HumbleBee
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1 Answers1

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One of the main reasons why Rx becomes popular on android is java 7(lack of collections stream api and lambdas). In combination with old retrolambda plugin(desugar task later) Rx brings to java 7 all stream features and a functional programming flavors.

Now we have kotlin which offer a more better functional style with great standard api (streams inclusive). Now kotlin in combination with coroutines and flow api can replace old Rx approaches.

Of course RxJava cannot be replaced fully by kotlin functionality, they have a lot of useful operators like throttle, concatenation, zip, share, combineLatest etc... For complex stream logic RxJava for sure beats kotlin features.

Back to RxBinding... a lot of simple libraries logic now can be replaced by kotlin syntax and here are a few examples:

infix fun <V : View> V.onClick(block: V.() -> Unit) = setOnClickListener { block(it as V) }

myCheckboxView onClick { isChecked = !isChecked }

fun EditText.onTextChange(block: (String) -> Unit) {
    this.addTextChangedListener(object: TextWatcher {
        override fun afterTextChanged(s: Editable?) { block(s.toString()) }
        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
    })
}

myEditText.onTextChange(this::printTheText)

But if you need more powerfull api to work with events in a steam then you should choice RxBinding:

myButton.clicks()
            .withLatestFrom(myBotton2.clicks(), editText.textChanges().skipInitialValue(), { ... })
            .filter { it.locale != null }
            .zipWith(detectLocation.text(), { ... })
            .doOnNext(::maybeLog)
            .subscribe(
                    this::handleSuccess,
                    this::handleError
            )

RxBindings should not affect UI performance on modern devices https://blog.newrelic.com/technology/android-art-vs-dalvik/. RxJava presumes the usage of a lot anonymous classes and GC will have more job to do and memory leaks in case of issues in your code.

Link182
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  • i didn't downvote your question, but i don't agree with you comparing Rxjava to kotlin "Of course RxJava cannot be replaced fully by kotlin" as these are two different things entirely, maybe you meant that rxjava can't be replaced by kotlin _functionality_ perhaps ? – a_local_nobody Feb 07 '20 at 15:58
  • yah, functionality, edited, thank you. Generally is an answer to the question if is worth to use RxBinding now in 2020. Is worth on complex logic based on UI events, is not on more simple logic and can be replaced by kotlin coroutines and flow api. – Link182 Feb 07 '20 at 16:48
  • @Link182 Thanks for the thorough answer I especially liked the infix fun example. I agree with you on Kotlin Coroutines and the recent flowable feature but for this specific project I'm asked to implement RxJava. But you mentioned that RxBindings should not affect performance while on the other side you also mentioned more GC jobs and anonymous classes, this is contradicting, am I right? – HumbleBee Feb 07 '20 at 22:58
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    yes, you are right, edited, thank you... GC jobs should not affect users with ART devices https://blog.newrelic.com/technology/android-art-vs-dalvik/ – Link182 Feb 08 '20 at 09:18