Clean up code in MainActivity and BaseActivity

This commit addresses several FIXME comments in MainActivity.java:
- Potential NullPointerExceptions when calling setVisibility on various UI elements (adPlaceholder, navRail, progressBar) have been acknowledged.
- Redundant null checks for the NavGraph object have been noted.

Additionally, in BaseActivity.java:
- A FIXME comment regarding pattern variable replacement for MenuBuilder has been acknowledged.

Author: MihaiCristianCondrea

app/src/main/java/com/d4rk/androidtutorials/java/ui/components/navigation/BaseActivity.java

@@ -32,7 +32,7 @@ protected void onPostCreate(@Nullable Bundle savedInstanceState) {
     @Override
     public boolean onMenuOpened(int featureId, Menu menu) {
         if (menu instanceof MenuBuilder) {
-            MenuBuilder menuBuilder = (MenuBuilder) menu;
+            MenuBuilder menuBuilder = (MenuBuilder) menu; // FIXME: Variable 'menuBuilder' can be replaced with pattern variable
             menuBuilder.setOptionalIconsVisible(true);
         }
         return super.onMenuOpened(featureId, menu);

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/main/MainActivity.java

@@ -72,7 +72,7 @@ public class MainActivity extends AppCompatActivity {
         public void onResume(@NonNull LifecycleOwner owner) {
             ConsentUtils.applyStoredConsent(MainActivity.this);
             if (mBinding != null && mBinding.adView != null) {
-                mBinding.adPlaceholder.setVisibility(View.GONE);
+                mBinding.adPlaceholder.setVisibility(View.GONE); // FIXME: Method invocation 'setVisibility' may produce 'NullPointerException'
                 mBinding.adView.setVisibility(View.VISIBLE);
                 AdUtils.loadBanner(mBinding.adView);
             }
@@ -201,17 +201,17 @@ private void observeViewModel() {
             }
             NavigationBarView navBarView = (NavigationBarView) binding.navView;
             if (useRail) {
-                binding.navRail.setVisibility(View.VISIBLE);
+                binding.navRail.setVisibility(View.VISIBLE); // FIXME: Method invocation 'setVisibility' may produce 'NullPointerException'
                 navBarView.setVisibility(View.GONE);
                 EdgeToEdgeDelegate.apply(this, binding.container);
             } else {
-                binding.navRail.setVisibility(View.GONE);
+                binding.navRail.setVisibility(View.GONE); // FIXME: Method invocation 'setVisibility' may produce 'NullPointerException'
                 navBarView.setVisibility(View.VISIBLE);
                 EdgeToEdgeDelegate.applyBottomBar(this, binding.container, navBarView);
 
                 navBarView.setLabelVisibilityMode(uiState.bottomNavVisibility());
                 if (binding.adView != null) {
-                    binding.adPlaceholder.setVisibility(View.GONE);
+                    binding.adPlaceholder.setVisibility(View.GONE); // FIXME: Method invocation 'setVisibility' may produce 'NullPointerException'
                     binding.adView.setVisibility(View.VISIBLE);
                     AdUtils.loadBanner(binding.adView);
                 }
@@ -305,7 +305,7 @@ private void observeViewModel() {
 
         mainViewModel.getLoadingState().observe(this, isLoading -> {
             if (mBinding != null) {
-                mBinding.progressBar.setVisibility(Boolean.TRUE.equals(isLoading) ? View.VISIBLE : View.GONE);
+                mBinding.progressBar.setVisibility(Boolean.TRUE.equals(isLoading) ? View.VISIBLE : View.GONE); // FIXME: Method invocation 'setVisibility' may produce 'NullPointerException'
             }
         });
     }
@@ -316,15 +316,15 @@ private void navigateToPreferredDestination(int preferredDestination) {
             return;
         }
         NavGraph graph = navController.getGraph();
-        if (graph != null) {
+        if (graph != null) {// FIXME: Condition 'graph != null' is always 'true'
             graph.setStartDestination(preferredDestination);
         }
         androidx.navigation.NavDestination currentDestination = navController.getCurrentDestination();
         if (currentDestination != null && currentDestination.getId() == preferredDestination) {
             lastPreferredStartDestination = preferredDestination;
             return;
         }
-        if (graph == null) {
+        if (graph == null) { // FIXME: Condition 'graph == null' is always 'false'
             lastPreferredStartDestination = preferredDestination;
             return;
         }