Run app in Debug Working well, but build Release is crash!

[nguyenthao1988]

I'm using Samsung Galaxy A7, Android 8.0.
I working print brother label QL_720NW.
Run App Debug Print working, but app build release is crash app!

[bhaveshbusa]

@Srinivas11789, @YonathanZetune , @nguyenthao1988

This is little bit off topic. I have exactly the same problem. I am connecting QL_820NWB via bluetooth.

Printing works in Debug mode but fails when trying to StartCommunication.

printer.setPrinterInfo(settings); printer.startCommunication();

I have requested permission for external storage, set the workPath and tried bunch of other things

F art : art/runtime/check_jni.cc:65] JNI DETECTED ERROR IN APPLICATION: fid == null F art : art/runtime/check_jni.cc:65] in call to GetIntField F art : art/runtime/check_jni.cc:65] from void com.brother.ptouch.sdk.JNIWrapper.initJNI(com.brother.ptouch.sdk.h)

Checking if you guys have some pointers.

[dan12321]

I ran into the same error, not with this repo but when using the brother SDK. The issue in my case was ProGuard obfuscating the classes/methods/properties in com.brother.ptouch.sdk so they no longer matched with the native libraries (paraphrasing top answer from https://stackoverflow.com/questions/38151653/proguard-error-a-jni-error-has-occured). The result is that when the SDK tries to use the libraries with JNI (Java Native Interface), it crashes.

So the solution for me was to add -keep class com.brother.ptouch.sdk.** { *; } to my ProGuard configuration.

This contains more information on obfuscation in android https://developer.android.com/studio/build/shrink-code