Build android tools update

[patryk84a]

Describe the bug

While adding AAR libraries to the extension, I encountered a problem compiling the APK. The problem turned out to be a font file added to the library resources, in the res/font/font.ttf folder. The tools/libraries used by the build server are too old to handle this type of resource, so they return an error.

Affects

• Designer
• Blocks editor
• Projects Explorer
• Companion
• Compiled apps
• Buildserver
• Debugging
• Other... (please describe)

Expected behavior

AAR libraries shouldn't cause any problems during compilation. If we already have the ability to add AAR libraries, it should work flawlessly.

Steps to reproduce

Add any AAR library to the project that contains a font folder and, within it, a font file, e.g., ttf. If you don't have such a library, add the font folder with the ttf file to any AAR library. Then, when compiling the APK, you'll get an error.

[YashSachdeva]

I encountered this exact issue while trying to integrate an AAR library with custom fonts (res/font/*.ttf) into an App Inventor extension. The build server fails during APK compilation with errors related to unrecognized resource types, confirming the outdated tools are the culprit.

From reviewing the buildserver/build.xml and lib/android/tools, it looks like we're using SDK tools around r24 (e.g., common-24.3.0.jar, dx.jar), which lack proper support for modern AAR resources like res/font—introduced in Android 8.0 with AAPT2. Updating to newer versions (e.g., SDK tools 30+ with full AAPT2 and R8/D8 integration) should resolve this while maintaining compatibility.

I'd be happy to contribute by:

Testing the impact of updating the build tools on existing extensions and sample projects.
Proposing a PR to migrate from Ant to Gradle for better AAR handling, or at least bumping the SDK tools jars.
Documenting any breaking changes for the community.
Let me know how I can get involved—I've got some experience with Android builds and can dive into the specifics!

[ewpatton]

@patryk84a Do you encounter the same issue if you run #3571 locally?

[patryk84a]

I'll try it and let you know.

[patryk84a]

@ewpatton I tested this PR and unfortunately I get this error when building the APK, even without the TTF files.

[AttachNativeLibs] Starting Task
     [java] [AttachNativeLibs] Task succeeded in 0.002 seconds
     [java] [AttachAarLibs] Starting Task
     [java] paź 07, 2025 9:15:11 PM com.google.appinventor.buildserver.Compiler call
     [java] SEVERE: Error running task class com.google.appinventor.buildserver.tasks.android.AttachAarLibs
     [java] java.lang.reflect.InvocationTargetException
     [java]     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java]     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
     [java]     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.base/java.lang.reflect.Method.invoke(Method.java:566)
     [java]     at com.google.appinventor.buildserver.Compiler.call(Compiler.java:169)
     [java]     at com.google.appinventor.buildserver.Compiler.call(Compiler.java:33)
     [java]     at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
     [java]     at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
     [java]     at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
     [java]     at java.base/java.lang.Thread.run(Thread.java:829)
     [java] Caused by: java.lang.NullPointerException
     [java]     at java.base/java.io.File.<init>(File.java:278)
     [java]     at com.google.appinventor.buildserver.tasks.android.AttachAarLibs.execute(AttachAarLibs.java:55)
     [java]     at com.google.appinventor.buildserver.tasks.android.AttachAarLibs.execute(AttachAarLibs.java:29)
     [java]     ... 10 more
     [java]
     [java] [ERROR] null
     [java] [AttachAarLibs] Task errored