Custom class loading fails with java.lang.IllegalAccessError: Class ref in pre-verified class resolved to unexpected implementation

Question

I am trying to adjust the example from http://android-developers.blogspot.de/2011/07/custom-class-loading-in-dalvik.html to my needs. For this, I have a setup of 3 projects:

classloadingtest: Standard android application project containing the source of the MainActivity in the link above, slightly adjusted (moved the DexClassLoader business to a class named "AndroidClassLoader"), referencing the "iface" project below

iface: An android library project containing just an interface with only one function ("getMessage()") returning a String

loadable: A standard android application project also referencing the "iface" library containing just one class implementing that very simple interface and with a custom_rules.txt file adjusting the build process:

<?xml version="1.0" encoding="UTF-8"?>
<project name="BuildLoadableDex" default="debug">
    <target name="-dex" depends="-compile, -post-compile, -obfuscate">
        <echo level="info">Custom -dex target</echo>
        <property name="out.dex.input.absolute.dir" value="${out.classes.absolute.dir}" />
        <dex executable="${dx}"
                output="${intermediate.dex.file}"
                dexedlibs="${out.dexed.absolute.dir}"
                nolocals="@{nolocals}"
                forceJumbo="${dex.force.jumbo}"
                disableDexMerger="${dex.disable.merger}"
                verbose="${verbose}">
            <path path="${out.dex.input.absolute.dir}"/>
        </dex>
    </target>

    <target name="-package" depends="-dex, -package-resources">
        <echo level="info">Custom -package target</echo>
        <jar destfile="${out.absolute.dir}/${ant.project.name}.jar"
            basedir="${out.absolute.dir}"
            includes="${dex.file.name}" />
    </target>
</project>

So this essentially just modifies the -dex target to leave out the library classes from the classes.dex file (verified via dexdump not showing the interface) and changes the -package target to output a jar file instead of an apk.

I then copy the loadable.jar file to classloadingtest/assets and build that apk file.

Everything compiles fine, but when running and triggering the class loading, I get the following stack trace:

W/dalvikvm(14393): Class resolved by unexpected DEX: Lloadable/Test;(0x4294b620):0x5a6a7000 ref [Lclassloading/iface/LoadableClass;] Lclassloading/iface/LoadableClass;(0x42912fb8):0x5a4bf000
W/dalvikvm(14393): (Lloadable/Test; had used a different Lclassloading/iface/LoadableClass; during pre-verification)
I/dalvikvm(14393): Failed resolving Lloadable/Test; interface 6 'Lclassloading/iface/LoadableClass;'
W/dalvikvm(14393): Link of class 'Lloadable/Test;' failed
D/AndroidRuntime(14393): Shutting down VM
W/dalvikvm(14393): threadid=1: thread exiting with uncaught exception (group=0x41c622a0)
E/AndroidRuntime(14393): FATAL EXCEPTION: main
E/AndroidRuntime(14393): java.lang.IllegalAccessError: Class ref in pre-verified class resolved to unexpected implementation
E/AndroidRuntime(14393):        at dalvik.system.DexFile.defineClass(Native Method)
E/AndroidRuntime(14393):        at dalvik.system.DexFile.loadClassBinaryName(DexFile.java:211)
E/AndroidRuntime(14393):        at dalvik.system.DexPathList.findClass(DexPathList.java:315)
E/AndroidRuntime(14393):        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:58)
E/AndroidRuntime(14393):        at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
E/AndroidRuntime(14393):        at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
E/AndroidRuntime(14393):        at classloading.loading.AndroidClassLoader.findClass(AndroidClassLoader.java:56)
E/AndroidRuntime(14393):        at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
E/AndroidRuntime(14393):        at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
E/AndroidRuntime(14393):        at classloading.loading.AndroidClassLoader.loadClass(AndroidClassLoader.java:37)
E/AndroidRuntime(14393):        at classloading.ClassLoadingTest$1.onClick(ClassLoadingTest.java:60)
E/AndroidRuntime(14393):        at android.view.View.performClick(View.java:4211)
E/AndroidRuntime(14393):        at android.view.View$PerformClick.run(View.java:17267)
E/AndroidRuntime(14393):        at android.os.Handler.handleCallback(Handler.java:615)
E/AndroidRuntime(14393):        at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(14393):        at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(14393):        at android.app.ActivityThread.main(ActivityThread.java:4898)
E/AndroidRuntime(14393):        at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(14393):        at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(14393):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
E/AndroidRuntime(14393):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
E/AndroidRuntime(14393):        at dalvik.system.NativeStart.main(Native Method)

I do get that this means that somehow the LoadableClass interface "seems" to exist two times with differences, but I just can't understand how this happens, seeing both the APK (classloadingtest) and the loadable.jar use the exact same library project for compiling, thus I have no idea of how to fix this error.

Please feel free to request edits with more code, I just don't know what might be useful here and don't want to paste everything .

Answer 1

Stupidity resolved, I've been trying to load an old version of loadable.jar. Leaving this here so others might benefit and not waste that much time.