Alexander Alexander - 3 years ago 192
Android Question

ProGuard leads to NullPointerException

When setting

minifyEnabled true
in my gradle I get a NullPointerException when starting my app:

java.lang.RuntimeException: Unable to start activity ComponentInfo{de.ae.formulaecalendar/de.ae.formulaecalendar.view.calendar.CalendarActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2444)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2504)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1367)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5461)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
at de.ae.formulaecalendar.view.calendar.CalendarActivity.onCreate(Unknown Source)
at android.app.Activity.performCreate(Activity.java:6251)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2397)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2504) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1367) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5461) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 


While reading through StackOverflow I found some settings for the proguard-rules.pro file:

######### KEEP ANDROID SUPPORT V7 AND DESIGN
-keep class android.support.v7.** { *; }
-keep interface android.support.v7.** { *; }


which didn't really solve this problem (but a previous NullPointerException).

Finally the important part of my gradle:

buildTypes {
release {
shrinkResources true
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
signingConfig signingConfigs.config
}
}


When I disbale
minifyEnabled
everthing works fine.

Thanks for your help!

Answer Source

I solved the problem:

After running Clean Project in Android Studio I got an error about a file called resource-release-stripped.ap_ that cannot be found. Some searching via Google showed up that I need to disable shrinkResources in the gradle file because it is not compatible with Jack.

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