Realm-java: ReLinker NoClassDefFoundError exception

[lukcz]

Using 8.8.0-SNAPSHOT:

java.lang.NoClassDefFoundError: Failed resolution of: Lcom/getkeepsafe/relinker/ReLinker;
at io.realm.internal.RealmCore.loadLibrary(RealmCore.java:90)
at io.realm.RealmConfiguration$Builder.(RealmConfiguration.java:307)
at com.borg.forza.activities.Forza.setupRealm(Forza.java:75)
at com.borg.forza.activities.Forza.onCreate(Forza.java:63)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1034)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4605)
at android.app.ActivityThread.access$1500(ActivityThread.java:148)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1353)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5312)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.getkeepsafe.relinker.ReLinker" on path: DexPathList[[zip file "/mnt/asec/com.borg.forza-1/base.apk"],nativeLibraryDirectories=[/mnt/asec/com.borg.forza-1/lib/arm, /vendor/lib, /system/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
at io.realm.internal.RealmCore.loadLibrary(RealmCore.java:90) 
at io.realm.RealmConfiguration$Builder.(RealmConfiguration.java:307) 
at com.borg.forza.activities.Forza.setupRealm(Forza.java:75) 
at com.borg.forza.activities.Forza.onCreate(Forza.java:63) 
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1034) `

[cmelchior]

Are you using ProGuard by any chance?

[lukcz]

Yes,
the rules taken from https://realm.io/docs/java/latest/#proguard:

-keep class io.realm.annotations.RealmModule
-keep @io.realm.annotations.RealmModule class *
-keep class io.realm.internal.Keep
-keep @io.realm.internal.Keep class * { _; }
-dontwarn javax._*
-dontwarn io.realm.**

[cmelchior]

Hi @roughboy
I was tried to run our example project with ProGuard enabled which seems to work fine: https://github.com/realm/realm-java/blob/master/examples/moduleExample/app/build.gradle

Note that if you use our new AAR distribution package as described here: https://github.com/realm/realm-java/blob/master/examples/moduleExample/app/build.gradle you don't need to provide your own ProGuard configuration.

[lukcz]

Hi, seems like yours example is using AAR distribution while I got ReLinker error while using standard distribution method - compile 'io.realm:realm-android:0.88.0-SNAPSHOT'

As regarding AAR distribution - I checked it too. Unfortunately this time I get following error from gradle console during compilation:

    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
    ... 70 more
Error:java.lang.NoClassDefFoundError: com/squareup/javawriter/JavaWriter
    at io.realm.processor.RealmProxyClassGenerator.generate(RealmProxyClassGenerator.java:50)
    at io.realm.processor.RealmProcessor.process(RealmProcessor.java:145)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
    at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
    at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
    at com.sun.tools.javac.main.Main.compile(Main.java:523)
    ... 91 more
Error:java.lang.ClassNotFoundException: com.squareup.javawriter.JavaWriter
    ... 101 more

I put sample project with repro here:
https://drive.google.com/file/d/0B_iAqFNIegRpVmZMVUhTRFBSckU/view?usp=sharing

[Zhuinden]

Solution: add the Relinker dependency manually

compile 'io.realm:realm-android:0.88.0-SNAPSHOT'
compile 'com.github.KeepSafe:ReLinker:1.1'

With

#Relinker (for Realm 0.88.0+)
-keep class com.getkeepsafe.** { *; }
-keep class com.github.KeepSafe.** { *; }

[cmelchior]

The JAR will no longer be supported from 0.88 and onwards. As we use the new Transform API in order to support #2196, only the AAR and the Gradle plugin will be supported going forward.

[Zhuinden]

...so in order to use ReLinker, I have to switch to the new and fairly experimental Gradle-plugin.

I guess I'll have to pray for the best at this point.

[cmelchior]

Depending on what you mean by experimental, we support back to 1.5.0 of the Google build tools.

[Zhuinden]

I guess the question is, can I seamlessly upgrade from the JAR version to the AAR Gradle-Plugin without having to migrate, and will it be as stable on low-end devices and BlackBerry considering you guys are manipulating bytecode.

[cmelchior]

Yes, the upgrade from JAR to AAR does not require a migration of data. It is part of a larger release though which will have other breaking changes. You can see the current list in our changelog: https://github.com/realm/realm-java/blob/master/CHANGELOG.md

We are using standard tools and API's for manipulating the bytecode: Transform API and JavaAssist, plus the changes we make are actually a lot simpler than e.g. what Retrolambda and Instant Run do, so it should be safe.

[Zhuinden]

Luckily, the only breaking change that affects me is having to switch to the Gradle plugin; otherwise my code is 0.84.0+ compatible (and with minor changes compatible back to 0.82.2) so the DynamicRealm doesn't affect me much.

The only interesting change is

BREAKING CHANGE: All thread local change listeners are now delayed 
    until the next Looper event instead of being triggered when committing.

Although I wasn't relying on that feature. Is there an issue for that somewhere? It essentially makes Realm objects not be up-to-date if you rely on saving data on the UI thread. I can see that cause trouble in basic examples.

[cmelchior]

It is part of a restructuring needed to support https://github.com/realm/realm-java/pull/2124

[Zhuinden]

Oh. I can see why that's necessary, using for(int i = 0; i < list.size(); i++) { for reliable iteration behavior is not very intuitive, I've run into that problem many times when I first started using Realm.

Well, I'll update my app to the Gradle plugin then, and hope for the best.

Thanks for the info.

[Zhuinden]

Wait, so how do I set up the AAR setup again?

Do I just need to use the Classpath dependency in the top-level build gradle

 classpath "io.realm:realm-gradle-plugin:${currentVersion}" //0.88.0-SNAPSHOT

and then in the app-level build gradle

apply plugin: 'realm-android'

But don't I need to still add a compile time dependency somewhere? Like,

compile 'io.realm:realm-android:0.88.0-SNAPSHOT'

Or is that no longer necessary with the new Gradle plugin? Maybe you have to set it as provided?

(I found this https://realm.io/news/android-installation-change/ so I guess the classpath and plugin are all that's needed...?)

[cmelchior]

@Zhuinden Yes, the only thing needed is the classpath and apply plugin. Our plugin will then automatically fetch all needed dependencies. You can see it working in our examples: https://github.com/realm/realm-java/blob/master/examples/introExample/build.gradle

If you are interested, you can see which dependencies we have here: https://github.com/realm/realm-java/blob/master/gradle-plugin/src/main/groovy/io/realm/gradle/Realm.groovy#L46-Lundefined , but it is done automatically.

[martarodriguezm]

Hi,

Same problem here, I have it working in one project without problems but I have this error in other where I am using realm inside a library.
Can I use realm gradle plugin inside an Android library?

Thanks!