method in converted class has illegal modifiers: 0xA

[stephentalley]

dex2jar successfully converts the classes in my apk to a jar file.

However, while attempting to inspect those classes in a desktop application with Class.forName(name, false) (note the initialize = false arg), I see this error:

error: unable to process AboutBottomSheet.kt: Method $jacocoInit in class androidx/lifecycle/HasDefaultViewModelProviderFactory has illegal modifiers: 0xA

After some investigating, I'm guessing this corresponds to a default modifier in the HasDefaultViewModelProviderFactory interface (defined by Android):

default CreationExtras getDefaultViewModelCreationExtras() {
    return CreationExtras.Empty.INSTANCE;
}

This modifier was introduced in Java 8 (52), but the Android classes are for Java 6 (50).

So I believe the error results from a newer modifier in an older class version where it was not supported.

Can someone with greater knowledge confirm this suspicion, or comment on what else might be going on?

Incidentally, I tried converting that class to level 52 with d2j-class-version-switch.sh, but the problem remains.

[ThexXTURBOXx]

Are you able to share either the whole APK or the specific class file where this issue occurs?

[stephentalley]

app-debug.zip

Attached is a barebones app where I can reproduce the problem.

Adding classes.jar (generated by d2j-dex2jar.sh) to my classpath and calling Class.forName("com.sas.android.prototype.MainActivity", false) leads to:

E:Main:Main.main:117:
java.lang.ClassFormatError: Method $jacocoInit in class androidx/lifecycle/HasDefaultViewModelProviderFactory has illegal modifiers: 0xA
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Class.java:398)
        at com.nerdysoftware.app.korder.Resolver$Companion.forName(Resolver.kt:538)
        at com.nerdysoftware.app.korder.Resolver.resolveSansCache(Resolver.kt:363)
        at com.nerdysoftware.app.korder.Resolver.resolve(Resolver.kt:268)
        at com.nerdysoftware.app.korder.Resolver.resolve(Resolver.kt:152)
        at com.nerdysoftware.app.korder.Formatter.output(Formatter.kt:299)
        at com.nerdysoftware.app.korder.Formatter.output(Formatter.kt:37)
        at com.nerdysoftware.app.korder.Main.main(Main.kt:111)

[ThexXTURBOXx]

Sorry, I thought I had responded here: Yes, I indeed think that it might be the default attribute that is causing problems here.
Normally, a 0xA should stand for private static. In the context of interfaces, I would imagine that this identifies a function that has an implementation, i.e., a function with a default attribute. However, this is just my guess.
I will see what I can do about this in a free minute :)

[stephentalley]

Hi @ThexXTURBOXx, have you had a chance to look into this further?

[ThexXTURBOXx]

I tagged this PR as being part of Hacktoberfest.
So, if someone is able to fix and properly test this issue, he is one step closer to completing Hacktoberfest 2022 :)

[stephentalley]

bump

Is there a workaround I might be able to use here? I just need to determine class hierarchy, so the attribute mismatch shouldn't be fatal.

[ThexXTURBOXx]

Alas, I am not sure if there is something, I am sorry. But honestly, I also have not yet had enough time to dig a bit deeper into this. I hope to be able to do this after finishing my Master's Thesis, but that will still take a while...

[stephentalley]

I understand. Good luck on your thesis!