Introduce consolidated MainUiState

Author: MihaiCristianCondrea

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

@@ -185,13 +185,17 @@ private void launcherShortcuts() {
     }
 
     private void observeViewModel() {
-        mainViewModel.getBottomNavVisibility().observe(this, visibilityMode -> {
+        mainViewModel.getUiState().observe(this, uiState -> {
+            if (uiState == null) {
+                return;
+            }
+
             EdgeToEdgeDelegate edgeToEdgeDelegate = new EdgeToEdgeDelegate(this);
             if (mBinding.navView instanceof BottomNavigationView) {
 
                 edgeToEdgeDelegate.applyEdgeToEdgeBottomBar(mBinding.container, mBinding.navView);
 
-                ((BottomNavigationView) mBinding.navView).setLabelVisibilityMode(visibilityMode);
+                ((BottomNavigationView) mBinding.navView).setLabelVisibilityMode(uiState.getBottomNavVisibility());
                 if (mBinding.adView != null) {
                     if (ConsentUtils.canShowAds(this)) {
                         MobileAds.initialize(this);
@@ -204,15 +208,13 @@ private void observeViewModel() {
             } else {
                 edgeToEdgeDelegate.applyEdgeToEdge(mBinding.container);
             }
-        });
 
-        mainViewModel.getDefaultNavDestination().observe(this, startFragmentId -> {
             NavHostFragment navHostFragment = (NavHostFragment)
                     getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment_activity_main);
             if (navHostFragment != null) {
                 navController = navHostFragment.getNavController();
                 NavGraph navGraph = navController.getNavInflater().inflate(R.navigation.mobile_navigation);
-                navGraph.setStartDestination(startFragmentId);
+                navGraph.setStartDestination(uiState.getDefaultNavDestination());
                 navController.setGraph(navGraph);
 
                 if (mBinding.navView instanceof BottomNavigationView bottomNav) {
@@ -228,10 +230,8 @@ private void observeViewModel() {
                     bottomSheet.show(getSupportFragmentManager(), bottomSheet.getTag());
                 });
             }
-        });
 
-        mainViewModel.getThemeChanged().observe(this, changed -> {
-            if (Boolean.TRUE.equals(changed)) {
+            if (uiState.isThemeChanged()) {
                 recreate();
             }
         });

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

@@ -0,0 +1,30 @@
+package com.d4rk.androidtutorials.java.ui.screens.main;
+
+/**
+ * UI state for {@link MainActivity}. Holds values related to the main screen such as
+ * bottom navigation visibility, the default navigation destination, and whether the theme
+ * has changed requiring a recreation of the activity.
+ */
+public class MainUiState {
+    private final int bottomNavVisibility;
+    private final int defaultNavDestination;
+    private final boolean themeChanged;
+
+    public MainUiState(int bottomNavVisibility, int defaultNavDestination, boolean themeChanged) {
+        this.bottomNavVisibility = bottomNavVisibility;
+        this.defaultNavDestination = defaultNavDestination;
+        this.themeChanged = themeChanged;
+    }
+
+    public int getBottomNavVisibility() {
+        return bottomNavVisibility;
+    }
+
+    public int getDefaultNavDestination() {
+        return defaultNavDestination;
+    }
+
+    public boolean isThemeChanged() {
+        return themeChanged;
+    }
+}

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

@@ -38,9 +38,7 @@ public class MainViewModel extends ViewModel {
     private final IsAppInstalledUseCase isAppInstalledUseCase;
     private final BuildShortcutIntentUseCase buildShortcutIntentUseCase;
     private final GetAppUpdateManagerUseCase getAppUpdateManagerUseCase;
-    private final MutableLiveData<Integer> bottomNavLabelVisibility = new MutableLiveData<>();
-    private final MutableLiveData<Integer> defaultNavDestination = new MutableLiveData<>();
-    private final MutableLiveData<Boolean> themeChanged = new MutableLiveData<>();
+    private final MutableLiveData<MainUiState> uiState = new MutableLiveData<>();
 
     @Inject
     public MainViewModel(ApplyThemeSettingsUseCase applyThemeSettingsUseCase,
@@ -83,11 +81,9 @@ public void applySettings(String[] themeValues,
                               String[] bottomNavBarLabelsValues,
                               String[] defaultTabValues) {
         boolean changedTheme = applyThemeSettingsUseCase.invoke(themeValues);
-        themeChanged.setValue(changedTheme);
 
         String labelVisibilityStr = getBottomNavLabelVisibilityUseCase.invoke();
         int visibilityMode = getVisibilityMode(labelVisibilityStr, bottomNavBarLabelsValues);
-        bottomNavLabelVisibility.setValue(visibilityMode);
 
         String startFragmentIdValue = getDefaultTabPreferenceUseCase.invoke();
         int startFragmentId;
@@ -100,7 +96,8 @@ public void applySettings(String[] themeValues,
         } else {
             startFragmentId = R.id.navigation_home;
         }
-        defaultNavDestination.setValue(startFragmentId);
+
+        uiState.setValue(new MainUiState(visibilityMode, startFragmentId, changedTheme));
         applyLanguageSettingsUseCase.invoke();
     }
 
@@ -133,24 +130,10 @@ public Intent getShortcutIntent(boolean isInstalled) {
     }
 
     /**
-     * Expose the bottom nav visibility as LiveData, so MainActivity can observe it.
-     */
-    public LiveData<Integer> getBottomNavVisibility() {
-        return bottomNavLabelVisibility;
-    }
-
-    /**
-     * Expose the default nav destination as LiveData, so MainActivity can observe it.
-     */
-    public LiveData<Integer> getDefaultNavDestination() {
-        return defaultNavDestination;
-    }
-
-    /**
-     * This tells the UI whether the theme changed so it can decide to recreate if necessary.
+     * Expose the consolidated UI state so MainActivity can observe it.
      */
-    public LiveData<Boolean> getThemeChanged() {
-        return themeChanged;
+    public LiveData<MainUiState> getUiState() {
+        return uiState;
     }
 
     /**