Error: java.lang.ClassNotFoundException: Didn't find class on path

[FabioNevesRezende]

I'm having this error when using Java.use trying to hook up into a java class under an Android 9 Virtual Machine from Android x86 project. The app is Uncrackable level 2 by OWASP. Steps to reproduce:

Run

frida -U -f owasp.mstg.uncrackable2 -l inject.js

where inject.js is:

console.log(`Injecting into process with PID ${Process.id}`)
console.log(`frida version: ${Frida.version}`)

const MainActivity = Java.use('sg.vantagepoint.uncrackable2.CodeCheck');

The output:

Injecting into process with PID 4276
frida version: 16.1.7
Error: java.lang.ClassNotFoundException: Didn't find class "sg.vantagepoint.uncrackable2.CodeCheck" on path: DexPathList[[directory "."],nativeLibraryDirectories=[/system/lib64, /system/vendor/lib64, /system/lib64, /system/vendor/lib64]]
at (frida/node_modules/frida-java-bridge/lib/env.js:124)
at (frida/node_modules/frida-java-bridge/lib/env.js:115)
at apply (native)
at (frida/node_modules/frida-java-bridge/lib/env.js:97)
at (frida/node_modules/frida-java-bridge/lib/class-factory.js:488)
at value (frida/node_modules/frida-java-bridge/lib/class-factory.js:945)
at value (frida/node_modules/frida-java-bridge/lib/class-factory.js:950)
at _make (frida/node_modules/frida-java-bridge/lib/class-factory.js:165)
at use (frida/node_modules/frida-java-bridge/lib/class-factory.js:62)
at use (frida/node_modules/frida-java-bridge/index.js:258)
at (~/Desktop/test/inject.js:4)
at evaluate (native)
at (/frida/repl-2.js:1)

[eybisi]

Make sure to wrap inject.js code inside the Java.perform