java.lang.IllegalStateException: Could not execute method for android:onClick at androidx.appcompat.app.l$a.onClick(Unknown Source:32) at android.view.View.performClick(View.java:7498) at android.view.View.performClickInternal(View.java:7471) at android.view.View.access$3700(View.java:843) at android.view.View$PerformClick.run(View.java:29098) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loopOnce(Looper.java:233) at android.os.Looper.loop(Looper.java:344) at android.app.ActivityThread.main(ActivityThread.java:8248) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:589) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1071) Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Method.invoke(Native Method) at androidx.appcompat.app.l$a.onClick(Unknown Source:23) ... 12 more Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void n8.b.d()' on a null object reference at n8.a$e.a(Unknown Source:2) at n8.a.c(Unknown Source:8) at com.entitcs.office_attendance.camera.FaceTrackerActivity.groupAttendance(Unknown Source:2) ... 14 more