Refactor home screen state management

Author: MihaiCristianCondrea

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/home/HomeFragment.java

@@ -32,13 +32,27 @@ public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
     public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);
         homeViewModel = new ViewModelProvider(this).get(HomeViewModel.class);
-        homeViewModel.getAnnouncementTitle().observe(getViewLifecycleOwner(), title -> binding.announcementTitle.setText(title));
-        homeViewModel.getAnnouncementSubtitle().observe(getViewLifecycleOwner(), subtitle -> binding.announcementSubtitle.setText(subtitle));
-        homeViewModel.getDailyTip().observe(getViewLifecycleOwner(), tip -> {
-            binding.tipText.setText(tip);
-            binding.shareTipButton.setOnClickListener(v -> shareTip(tip));
+        LayoutInflater inflater = LayoutInflater.from(requireContext());
+        homeViewModel.getUiState().observe(getViewLifecycleOwner(), state -> {
+            binding.announcementTitle.setText(state.announcementTitle());
+            binding.announcementSubtitle.setText(state.announcementSubtitle());
+            binding.tipText.setText(state.dailyTip());
+            binding.shareTipButton.setOnClickListener(v -> shareTip(state.dailyTip()));
+
+            ViewGroup promotedContainer = binding.promotedAppsContainer;
+            binding.scrollView.clearFocus();
+            promotedContainer.clearFocus();
+            promotedContainer.removeAllViews();
+            for (com.d4rk.androidtutorials.java.data.model.PromotedApp app : state.promotedApps()) {
+                com.d4rk.androidtutorials.java.databinding.PromotedAppItemBinding itemBinding =
+                        com.d4rk.androidtutorials.java.databinding.PromotedAppItemBinding.inflate(inflater, promotedContainer, false);
+                loadImage(app.iconUrl(), itemBinding.appIcon);
+                itemBinding.appName.setText(app.name());
+                itemBinding.appDescription.setVisibility(android.view.View.GONE);
+                itemBinding.appButton.setOnClickListener(v -> startActivity(homeViewModel.getPromotedAppIntent(app.packageName())));
+                promotedContainer.addView(itemBinding.getRoot());
+            }
         });
-        setupPromotions(LayoutInflater.from(requireContext()));
         new FastScrollerBuilder(binding.scrollView)
                 .useMd2Style()
                 .build();
@@ -67,24 +81,6 @@ private void shareTip(String tip) {
         startActivity(android.content.Intent.createChooser(shareIntent, getString(com.d4rk.androidtutorials.java.R.string.share_using)));
     }
 
-    private void setupPromotions(LayoutInflater inflater) {
-        ViewGroup container = binding.promotedAppsContainer;
-        homeViewModel.getPromotedApps().observe(getViewLifecycleOwner(), apps -> {
-            binding.scrollView.clearFocus();
-            container.clearFocus();
-            container.removeAllViews();
-            for (com.d4rk.androidtutorials.java.data.model.PromotedApp app : apps) {
-                com.d4rk.androidtutorials.java.databinding.PromotedAppItemBinding itemBinding =
-                        com.d4rk.androidtutorials.java.databinding.PromotedAppItemBinding.inflate(inflater, container, false);
-                loadImage(app.iconUrl(), itemBinding.appIcon);
-                itemBinding.appName.setText(app.name());
-                itemBinding.appDescription.setVisibility(android.view.View.GONE);
-                itemBinding.appButton.setOnClickListener(v -> startActivity(homeViewModel.getPromotedAppIntent(app.packageName())));
-                container.addView(itemBinding.getRoot());
-            }
-        });
-    }
-
     private void loadImage(String url, android.widget.ImageView imageView) {
         com.android.volley.toolbox.ImageRequest request = new com.android.volley.toolbox.ImageRequest(
                 url,

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/home/HomeUiState.java

@@ -0,0 +1,16 @@
+package com.d4rk.androidtutorials.java.ui.screens.home;
+
+import java.util.List;
+
+import com.d4rk.androidtutorials.java.data.model.PromotedApp;
+
+/**
+ * Represents the UI state for the Home screen.
+ */
+public record HomeUiState(
+        String announcementTitle,
+        String announcementSubtitle,
+        String dailyTip,
+        List<PromotedApp> promotedApps
+) {}
+

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/home/HomeViewModel.java

@@ -4,9 +4,9 @@
 import android.content.Intent;
 import android.net.Uri;
 
-import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
 
 import com.d4rk.androidtutorials.java.R;
 import com.d4rk.androidtutorials.java.data.model.PromotedApp;
@@ -29,10 +29,7 @@ public class HomeViewModel extends ViewModel {
     private final GetDailyTipUseCase getDailyTipUseCase;
     private final GetPromotedAppsUseCase getPromotedAppsUseCase;
 
-    private final MutableLiveData<String> announcementTitle = new MutableLiveData<>();
-    private final MutableLiveData<String> announcementSubtitle = new MutableLiveData<>();
-    private final MutableLiveData<String> dailyTip = new MutableLiveData<>();
-    private final MutableLiveData<List<PromotedApp>> promotedApps = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<HomeUiState> uiState = new MutableLiveData<>();
 
     @Inject
     public HomeViewModel(Application application,
@@ -44,43 +41,45 @@ public HomeViewModel(Application application,
         this.getDailyTipUseCase = getDailyTipUseCase;
         this.getPromotedAppsUseCase = getPromotedAppsUseCase;
 
-        announcementTitle.setValue(application.getString(R.string.announcement_title));
-        announcementSubtitle.setValue(application.getString(R.string.announcement_subtitle));
-        dailyTip.setValue(getDailyTipUseCase.invoke());
+        HomeUiState initialState = new HomeUiState(
+                application.getString(R.string.announcement_title),
+                application.getString(R.string.announcement_subtitle),
+                getDailyTipUseCase.invoke(),
+                new ArrayList<>()
+        );
+        uiState.setValue(initialState);
 
         getPromotedAppsUseCase.invoke(apps -> {
+            List<PromotedApp> result;
             if (apps.isEmpty()) {
-                promotedApps.postValue(apps);
-                return;
+                result = apps;
+            } else {
+                int startIndex = (int) ((System.currentTimeMillis() / (24L * 60 * 60 * 1000)) % apps.size());
+                result = new ArrayList<>();
+                for (int i = 0; i < Math.min(4, apps.size()); i++) {
+                    result.add(apps.get((startIndex + i) % apps.size()));
+                }
             }
-            int startIndex = (int) ((System.currentTimeMillis() / (24L * 60 * 60 * 1000)) % apps.size());
-            List<PromotedApp> rotated = new ArrayList<>();
-            for (int i = 0; i < Math.min(4, apps.size()); i++) {
-                rotated.add(apps.get((startIndex + i) % apps.size()));
+            HomeUiState current = uiState.getValue();
+            if (current == null) {
+                current = new HomeUiState("", "", "", result);
+            } else {
+                current = new HomeUiState(
+                        current.announcementTitle(),
+                        current.announcementSubtitle(),
+                        current.dailyTip(),
+                        result
+                );
             }
-            promotedApps.postValue(rotated);
+            uiState.postValue(current);
         });
     }
 
     /**
-     * Provides a LiveData for the announcement title.
-     */
-    public LiveData<String> getAnnouncementTitle() {
-        return announcementTitle;
-    }
-
-    /**
-     * Provides a LiveData for the announcement subtitle.
-     */
-    public LiveData<String> getAnnouncementSubtitle() {
-        return announcementSubtitle;
-    }
-
-    /**
-     * Provides a LiveData for the tip of the day text.
+     * Exposes the UI state for the Home screen.
      */
-    public LiveData<String> getDailyTip() {
-        return dailyTip;
+    public LiveData<HomeUiState> getUiState() {
+        return uiState;
     }
 
     /**
@@ -91,13 +90,6 @@ public Intent getOpenPlayStoreIntent() {
         return buildPlayStoreIntent(homeRepository.getPlayStoreUrl());
     }
 
-    /**
-     * List of apps to promote on the Home screen.
-     */
-    public LiveData<List<PromotedApp>> getPromotedApps() {
-        return promotedApps;
-    }
-
     /**
      * Builds an intent to open the Google Play listing for the provided package.
      */