App Bundle, split APKs and Multidex

Your app might observe crashes due to UnsatisfiedLinkError or LinkageError (since ObjectBox 2.3.4) on some devices. This has mainly two reasons: If your app uses the App Bundle format, the legacy split APK feature or Multidex the native library can't be found. Or if your minimum SDK is below API 23 (Marshmallow), there are known bugs in Android's native library loading code.

Let us know if you have more info on this in GitHub issue 605.

App Bundle and split APKs

When using an App Bundle or split APKs Google Play only delivers the split APKs required for each user's device configuration, including its architecture (ABI). If users bypass Google Play to install your app ("sideloading") they might not install all of the required split APKs. If the split APK containing the ObjectBox native library required for the device ABI is missing, your app will crash with LinkageError when building BoxStore.

Using the Play Core library to check for missing splits

Google-certified devices (those running Google Play Services) or those running Android 10 (API level 29) or higher prevent users from sideloading split APKs, making the below check redundant.

Add the Play Core library to the dependencies block:

implementation 'com.google.android.play:core:1.7.3'

In the Application class add the missing split APKs check before calling super.onCreate():

public class App extends Application {
@Override
public void onCreate() {
if (MissingSplitsManagerFactory.create(this).disableAppIfMissingRequiredSplits()) {
return; // Skip app initialization.
}
super.onCreate();
// ...
}
}

If a broken installation is detected, users will see a message and Reinstall button asking them to re-install the app from Google Play.

See how we updated our example app to use the Play Core library detection.

If the Play Core library should not be used, there are two alternatives:

Alternative: Catch exception and inform users

You can guard the MyObjectBox build call and for example display an activity with an info message (e.g. direct users to reinstall the app from Google Play, send you an error report, ...):

// guard the build call and set some flag (here setting the boxStore field null)
try {
boxStore = MyObjectBox.builder()
.androidContext(context.getApplicationContext())
.build();
} catch (LinkageError e) {
boxStore = null;
Log.e(App.TAG, "Failed to load ObjectBox: " + e.getMessage());
}
// then for example in the main activity check the flag in onCreate and
// direct to an info/error message without the app crashing:
if (ObjectBox.get() == null) {
startActivity(new Intent(this, ErrorActivity.class));
finish();
return;
}

As an example see how we added this to our Android app example.

Alternative: turn off splitting by ABI

The simplest solution is to always include native libraries for all supported ABIs. However, this will increase the download size of your app for all users.

android {
bundle {
abi {
// This property is set to true by default.
enableSplit = false
}
}
}

Source: Android Developers

Buggy devices

On some devices and if your minimum SDK is below API 23 (Marshmallow), loading the native library may fail due to bugs. To counter this ObjectBox includes support for the ReLinker tool which will try to extract the native library manually if loading it normally fails.

To set this up add ReLinker to your dependencies:

implementation 'com.getkeepsafe.relinker:relinker:1.3.1'

ObjectBox is calling ReLinker via reflection. If you are using ProGuard or Multidex, make sure to add keep rules so that ReLinker code is not stripped from the final app or is not in the primary dex file.

For ProGuard add this line:

-keep class com.getkeepsafe.relinker.** { *; }

For Multidex add a multiDexKeepProguard file to your build file:

android {
buildTypes {
release {
multiDexKeepProguard file('multidex-config.pro')
}
}
}

And in the multidex-config.pro file add the same rule as above:

-keep class com.getkeepsafe.relinker.** { *; }

Multidex supports two file formats to keep files. We are using the ProGuard format (multiDexKeepProguard property). You can also use the multiDexKeepFile property, but make sure to adapt the rule above to that format.

Enable ReLinker debug log

To enable debug logs for ReLinker you can pass a custom ReLinkerInstance when building BoxStore:

boxStore = MyObjectBox.builder()
.androidContext(App.this)
.androidReLinker(ReLinker.log(new ReLinker.Logger() {
@Override
public void log(String message) { Log.d(TAG, message); }
}))
.build();