java.lang.NoClassDefFoundError：更新 Gradle Android 插件时失败的解析：Landroidx/work/R

Question

I started updating dependencies for an older project of mine, but then noticed that the app does not start after some dep updates - it thows a java.lang.NoClassDefFoundError: Failed resolution of: Landroidx/work/R$bool exception. This might happen because on startup I reschedule a Worker to do some periodic IO.

I narrowed it down to the com.android.tools.build:gradle:3.5.1 -> com.android.tools.build:gradle:3.6.1 change in build.gradle and this does correspond with the docs but that does not help much.

A bit more context about the current set up where the problem occurs:

• I use the old classpath and version for the work library with implementation "android.arch.work:work-runtime-ktx:1.0.1"

• I tried reproducing this set up in a test project with no success, which might indicate that this is some kind of cache problem. I tried removing them with rm -rf ~/.gradle/caches but that did not help

• Android Studio also displays this problem in the WorkManagerImpl.java file (from the work library source) which would indicate that this indeed is not a gradle cache issue

EDIT 1: I tried removing the androidx:work package uses and the this exception is thrown by another support library from the androidx group. This points me to there being some there being some other funky class processing going on.

EDIT 2: I've found the solution, and this would apply to any android.support libraries - a gradle plugin realm-android was messing up the build, so updating it seems to have fixed the problem. Similar problems might occur with other code-generating plugins.

Any tips on how to approach this would be appreciated

Answer 1

As the OP sayed, it could be any other plugin or dependency as well. In my case, the error came from the ObjectBox plugin.

Updating ObjectBox from 2.5 to 2.6 solved the issue for me.

objectboxVersion = '2.6.0'

However, I needed to add the following lines to my build.gradle for ObjectBox to work again.

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8
    }