[Leanback] Header State initialized with `HEADERS_HIDDEN` cause Fragment.getView() to not be null

Expected Behavior

Reference:

• Leanback Android Application project
• com.example.android.tvleanback.ui.MainFragment.java

App launched with setHeaderState(HEADERS_HIDDEN) should hide the header and still display the rows.

Current Behavior

On app launched, it is not displaying any items in the MainFragment.java.

Pressing anything else on the D-pad (e.g. Press down), it will crash the app with the logs below:

2020-01-10 18:23:40.662 32294-32294/com.example.android.tvleanback E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android.tvleanback, PID: 32294
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View androidx.fragment.app.Fragment.getView()' on a null object reference
        at androidx.leanback.app.BrowseSupportFragment$4.onFocusSearch(BrowseSupportFragment.java:1096)
        at androidx.leanback.widget.BrowseFrameLayout.focusSearch(BrowseFrameLayout.java:118)
        at android.view.ViewGroup.focusSearch(ViewGroup.java:967)
        at android.view.View.focusSearch(View.java:10171)
        at android.view.ViewRootImpl$ViewPostImeInputStage.performFocusNavigation(ViewRootImpl.java:4664)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4782)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4605)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4293)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4350)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4326)
        at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4487)
        at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2435)
        at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1998)
        at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1989)
        at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2412)
        at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:325)
        at android.os.Looper.loop(Looper.java:142)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

Note

Pressing left D-pad will open the Header and start to display the items.

Possible Solution

Steps to Reproduce (for bugs)

In https://github.com/android/tv-samples/blob/master/Leanback/app/src/main/java/com/example/android/tvleanback/ui/MainFragment.java#L146

Change setHeadersState(HEADERS_ENABLED); to setHeadersState(HEADERS_HIDDEN);

    private void setupUIElements() {
        setBadgeDrawable(
                getActivity().getResources().getDrawable(R.drawable.videos_by_google_banner, null));
        setTitle(getString(R.string.browse_title)); // Badge, when set, takes precedent over title
-       setHeadersState(HEADERS_ENABLED);
+       setHeadersState(HEADERS_HIDDEN);
        setHeadersTransitionOnBackEnabled(true);

Context

We would like to launch the App without the header.

Your Environment

Build

• Compiled Android SDK version 28
• androidx.leanback:leanback:1.0.0

Running on

• Android version 8.1.0
• Xiaomi TV-box (Android TV)

[IanGClifton]

Note, I’ve also filed this at https://issuetracker.google.com/issues/147614095

[IanGClifton]

Thank you for the detailed report! I’ve confirmed this issue and also verified it happens on other devices, with leanback 1.0.0 and 1.1.0-alpha03, whether setHeadersState(HEADERS_HIDDEN) is called in onActivityCreated or onViewCreated.