Tag: Kotlin

Making arguments work in Compose Navigation where there was XML

Jetpack Compose Navigation goes hand in hand with Jetpack Compose. The issue comes when you are coming from XML navigation. Passing arguments between screens is very easy in XML and by extending from Java.Serializable interface, everything was working like magic. But now, you open the Pandora’s box with Jetpack Compose and here is how you could fix it.

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How to tackle the R8 optimisation nightmare in a sane way?

Implementing R8 optimizations can always be a nightmare for the dev that has to do it. R8 is a compiler that works together with ProGuard to shrink, minify, and obfuscate your code. It can reduce significantly the APK size by removing classes that are not used at all. It checks the hierarchy of classes and once it sees a class is not being attached to anything, it removes it.

The above, of course, is a double-edged sword as in some cases, it can remove classes that you actually need like request/response classes and many others. But in a recent project, we got like 10 megabytes of reduced APK size (down from 30) which is a huge gain.

The problem comes when you want to tell R8 to keep certain classes that you need either deobfuscated or simply kept within your dex archive. So let’s see what the approach could be in such cases.

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Downsides of Firebase Realtime DB for Android

There are a couple of downsides we figured out in our daily work with Firebase Realtime Database for Android and I would like to share them with you here. All of them revolve around using the provided SDK for Android. So let’s start.

Data listeners cannot be stopped

If you initiate a listener to observe some data like this one for example:

mDatabase.child("users").child(userId).get().addOnSuccessListener {
    Log.i("firebase", "Got value ${it.value}")
}.addOnFailureListener{
    Log.e("firebase", "Error getting data", it)
}

Then you may need to cancel it if your user leaves the screen where this data is presented. There is a cancel() method that you can call but unfortunately, this cancel method only removes the listener callback but does not cancel the operation going on in the background and lets it run until this completes.

Now imagine if you require a good big chunk of data for the screen and the user just does not want to wait because he has a 3G connection. You call cancel but the operation is still there in the background. You can verify logcat for that. What happens is that this operation still uses RAM memory that your app may need for something else and you can easily hit an OOM exception.

So for querying big datasets, it is best if you have a dedicated server that returns only the data that you need to work with.

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Creating a SonarQube custom plugin for Kotlin

In Android we decided that we want to implement a unit test performance monitor. The reason for it is that sometimes some unit tests would execute in more than 1 second and it was all because we would use the Schedulers.trampoline() RxJava scheduler instead of the TestScheduler which is part of the RX package.

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