Fix NPE crash in UwbPreferenceController and optimize the lifecycle observer adding condition in page

This patch contains two fixes:

- Make sure mUwbManager is non-null by calling isUwbSupportedOnDevice to avoid a NPE.
- Modify AdvancedConnectedDeviceDashboardFragment, add lifecycle observer only if device supports UWB.

Bug: 244871579

Test: manual test and Robotest.
Change-Id: I78f97794a66f3fb487f067c4570899e21c254acf

src/com/android/settings/connecteddevice/AdvancedConnectedDeviceDashboardFragment.java

@@ -69,10 +69,14 @@ public class AdvancedConnectedDeviceDashboardFragment extends DashboardFragment
     public void onAttach(Context context) {
         super.onAttach(context);
         UwbPreferenceController uwbPreferenceController = use(UwbPreferenceController.class);
-        if (uwbPreferenceController != null && getSettingsLifecycle() != null) {
+        // We only need the observer listen to the broadcast in the background for refreshing
+        // UI if the device supports UWB.
+        if (uwbPreferenceController != null && uwbPreferenceController.isUwbSupportedOnDevice()) {
+            if (getSettingsLifecycle() != null) {
                 getSettingsLifecycle().addObserver(uwbPreferenceController);
             }
         }
+    }
 
     @Override
     protected List<AbstractPreferenceController> createPreferenceControllers(Context context) {

src/com/android/settings/uwb/UwbPreferenceController.java

@@ -75,8 +75,7 @@ public class UwbPreferenceController extends TogglePreferenceController implemen
         };
     }
 
-    @VisibleForTesting
+    public boolean isUwbSupportedOnDevice() {
-    boolean isUwbSupportedOnDevice() {
         return mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_UWB);
     }
 
@@ -99,6 +98,9 @@ public class UwbPreferenceController extends TogglePreferenceController implemen
 
     @Override
     public boolean isChecked() {
+        if (!isUwbSupportedOnDevice()) {
+            return false;
+        }
         int state = mUwbManager.getAdapterState();
         return state == STATE_ENABLED_ACTIVE || state == STATE_ENABLED_INACTIVE;
     }