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SecUSo / privacy-friendly-qr-scanner

Privacy Friendly QR Code Scanner for Android
https://secuso.aifb.kit.edu/QR_Scanner.php
GNU General Public License v3.0
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java.lang.NullPointerException in some cases #177

Closed Marukohe closed 10 months ago

Marukohe commented 10 months ago

Hello, I find in some cases, the app will crash because of NPE problem. Here is the stack trace:

Caused by: java.lang.NullPointerException
    at java.util.Objects.requireNonNull(Objects.java:220)
    at java.util.Arrays$ArrayList.<init>(Arrays.java:4248)
    at java.util.Arrays.asList(Arrays.java:4235)
    at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:165)
    at com.secuso.privacyfriendlycodescanner.qrscanner.ui.activities.generator.QrGeneratorDisplayActivity.newErrorCorrectionAdapter(QrGeneratorDisplayActivity.java:179)
    at com.secuso.privacyfriendlycodescanner.qrscanner.ui.activities.generator.QrGeneratorDisplayActivity.onResume(QrGeneratorDisplayActivity.java:232)
    at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1531)
    at android.app.Activity.performResume(Activity.java:8422)
    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:4793)
    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:4836) 
    at android.app.servertransaction.ResumeActivityItem.execute(ResumeActivityItem.java:54) 
    at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45) 
    at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:176) 
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2308) 
    at android.os.Handler.dispatchMessage(Handler.java:106) 
    at android.os.Looper.loopOnce(Looper.java:201) 
    at android.os.Looper.loop(Looper.java:288) 
    at android.app.ActivityThread.main(ActivityThread.java:7898) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)

After reading the soure code, I may find the reason. When QrGeneratorDisplayActivity#onResume, QrGeneratorDisplayActivity#newErrorCorrectionAdapter will be invoked. The parameter currentErrorCorrections in some cases will be assigned to null in QrGeneratorDisplayActivity#updateDropDownMenus. So a NPE happens in some cases.

Here is a video which can trigger the crash.

https://github.com/SecUSo/privacy-friendly-qr-scanner/assets/32957242/1d4e5403-f8aa-431d-8f26-fc6eea776491

Device : Google pixel 4 OS: Android 12.

udenr commented 10 months ago

Thanks for the detailed description and the video. I will have a look at it.