java.lang.ClassCastException when searching for field usage

[j4k0xb]

Reproduction steps:

1. Open the apk from here
2. Go to the public int A; field in the e.a.b.d0 class
3. Find Usage

Info:

• Jadx version: 1.4.0
• Java version: 11.0.15
• Java VM: Oracle Corporation OpenJDK 64-Bit Server VM
• Platform: Linux (5.15.32-1-MANJARO amd64)
• Max heap size: 11116 MB
• Program args: -Xms128M -XX:MaxRAMPercentage=70.0 -XX:+UseG1GC -Dawt.useSystemAAFontSettings=lcd -Dswing.aatext=true

Stacktrace:

java.lang.ClassCastException: class jadx.api.JavaClass cannot be cast to class jadx.api.JavaVariable (jadx.api.JavaClass and jadx.api.JavaVariable are in unnamed module of loader 'app')
	at jadx.api.JadxDecompiler.resolveVarRef(JadxDecompiler.java:689)
	at jadx.api.JadxDecompiler.getJavaNodeByCodeAnnotation(JadxDecompiler.java:661)
	at jadx.api.JavaClass.getUsePlacesFor(JavaClass.java:203)
	at jadx.gui.ui.dialog.UsageDialog.processUsage(UsageDialog.java:101)
	at jadx.gui.ui.dialog.UsageDialog.lambda$null$1(UsageDialog.java:69)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
	at java.base/java.util.stream.DistinctOps$1$2.accept(DistinctOps.java:175)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
	at jadx.gui.ui.dialog.UsageDialog.lambda$collectUsageData$2(UsageDialog.java:69)
	at java.base/java.util.HashMap.forEach(HashMap.java:1337)
	at jadx.gui.ui.dialog.UsageDialog.collectUsageData(UsageDialog.java:66)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

[skylot]

@j4k0xb thanks!
I commit a fix. It is actually a workaround because I still not resolve all causes, but at least this will not throw class cast exception.

[skylot]

I think I fixed the root cause of the issue: disk cache uses too small number type (short) to store code offsets, so sometimes value overflows. I update that format to variable length encoding: ULEB128 (also used in dex) to use less disk space because most classes are not very big.

@j4k0xb you can check the latest unstable build, let me know if you find any new issues 🙂

[j4k0xb]

couldnt find any other issue 🙂

[j4k0xb]

@skylot
nvm I encountered another error (jadx built at commit 5099e02).
Could also be related to disk cache, or because it's a split apk?

Reproduction steps:

1. Open base.zip (rename to .apk)
2. Go to com.moshbit.studo.home.HomePagerAdapter
3. Click on it's class name and find usage

Stacktrace:

jadx.core.utils.exceptions.JadxRuntimeException: JavaMethod not found by MethodNode: kotlin.collections.MapsKt.mapOf(kotlin.Pair):java.util.Map
	at jadx.api.JadxDecompiler.getJavaMethodByNode(JadxDecompiler.java:556)
	at jadx.api.JadxDecompiler.getJavaNodeByCodeAnnotation(JadxDecompiler.java:653)
	at jadx.api.JavaClass.getUsePlacesFor(JavaClass.java:209)
	at jadx.gui.ui.dialog.UsageDialog.processUsage(UsageDialog.java:101)
	at jadx.gui.ui.dialog.UsageDialog.lambda$collectUsageData$1(UsageDialog.java:69)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
	at java.base/java.util.stream.DistinctOps$1$2.accept(DistinctOps.java:175)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
	at jadx.gui.ui.dialog.UsageDialog.lambda$collectUsageData$2(UsageDialog.java:69)
	at java.base/java.util.HashMap.forEach(HashMap.java:1337)
	at jadx.gui.ui.dialog.UsageDialog.collectUsageData(UsageDialog.java:66)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

[skylot]

@j4k0xb sadly but I can't reproduce this issue, maybe it is a multithreaded issue.
I will try to add more logging and maybe fix some paths of possible cause.

[skylot]

@j4k0xb I commit another bunch of changes, hope it will fix these issues.

[j4k0xb]

but I can't reproduce this issue

Just tried it again with the old version and couldn't reproduce it either.
Find usage works fine so I can't tell if it's fixed, but unless it happens again I think this issue can stay closed 😅