Migrated to AndroidX but app crashes on back button press

[zeeshanaslam78]

Recently I migrated to AndroidX in one of my project. App is crashing when I press back button from the activity in which I used SlidingMenu.

I am getting NullPointerException in onKeyUp function of SlidingFragmentActivity

at com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity.onKeyUp(SlidingFragmentActivity.java:149)

Here is the error

java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.fragment.app.FragmentManagerImpl.dispatchDestroy()' on a null object reference at androidx.fragment.app.Fragment.performDestroy(Fragment.java:2825) at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1028) at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238) at androidx.fragment.app.BackStackRecord.executePopOps(BackStackRecord.java:496) at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2076) at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869) at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824) at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:310) at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:253) at androidx.fragment.app.FragmentManagerImpl.handleOnBackPressed(FragmentManagerImpl.java:233) at androidx.fragment.app.FragmentManagerImpl$1.handleOnBackPressed(FragmentManagerImpl.java:108) at androidx.activity.OnBackPressedDispatcher.onBackPressed(OnBackPressedDispatcher.java:189) at androidx.activity.ComponentActivity.onBackPressed(ComponentActivity.java:286) at net.wadic.myhospital.DrawerActivity.onBackPressed(DrawerActivity.java:280) at android.app.Activity.onKeyUp(Activity.java:3147) at com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity.onKeyUp(SlidingFragmentActivity.java:149) at android.view.KeyEvent.dispatch(KeyEvent.java:2739) at android.app.Activity.dispatchKeyEvent(Activity.java:3430) at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:115) at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:84) at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:133) at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:558) at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59) at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2814) at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:352) at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5233) at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:5101) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4620) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4673) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4639) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4779) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4647) at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4836) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4620) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4673) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4639) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4647) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4620) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4673) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4639) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4812) at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4975) at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2580) at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:2090) 2020-01-30 00:52:56.612 21593-21593/net.wadic.myhospital.dev E/AndroidRuntime: at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:2081) at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2557) at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141) at android.os.MessageQueue.nativePollOnce(Native Method) at android.os.MessageQueue.next(MessageQueue.java:326) at android.os.Looper.loop(Looper.java:165) at android.app.ActivityThread.main(ActivityThread.java:6806) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

Does anyone know what should I do to get rid of this error ?

[EbelloImbox]

You have to change this conditionif (KeyEventCompat.hasNoModifiers(event)) { and else to:

if (event.hasNoModifiers()) {
	handled = arrowScroll(FOCUS_FORWARD);
} else if (event.hasModifiers(KeyEvent.META_SHIFT_ON)) {
	handled = arrowScroll(FOCUS_BACKWARD);
}