Add Room database lesson with basic CRUD demo

CHANGELOG.md

@@ -7,6 +7,7 @@
 - **Minor**: Added a search function for lessons.
 - **Patch**: Optimized app performance for smoother operation.
 - **Patch**: Updated several components to improve compatibility.
+- **New**: Added a Room database lesson demonstrating entity, DAO, and code viewer integration.
 
 # Version 5.0.1:
 

app/build.gradle

@@ -96,6 +96,8 @@ dependencies {
     implementation libs.codeview
     implementation libs.hilt.android
     annotationProcessor libs.hilt.compiler
+    implementation libs.androidx.room.runtime
+    annotationProcessor libs.androidx.room.compiler
 
     // Testing
     testImplementation libs.junit

app/src/main/AndroidManifest.xml

@@ -304,6 +304,18 @@
             android:label="@string/navigation_drawer"
             android:parentActivityName=".ui.screens.main.MainActivity" />
 
+        <activity
+            android:name=".ui.screens.android.lessons.data.room.RoomActivity"
+            android:exported="false"
+            android:label="@string/room_database"
+            android:parentActivityName=".ui.screens.main.MainActivity" />
+
+        <activity
+            android:name=".ui.screens.android.lessons.data.room.RoomCodeActivity"
+            android:exported="false"
+            android:label="@string/room_database"
+            android:parentActivityName=".ui.screens.android.lessons.data.room.RoomActivity" />
+
         <activity
             android:name=".ui.screens.settings.SettingsActivity"
             android:exported="false"

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/AppDatabase.java

@@ -0,0 +1,29 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room;
+
+import android.content.Context;
+
+import androidx.room.Database;
+import androidx.room.Room;
+import androidx.room.RoomDatabase;
+
+/**
+ * The Room database that holds the notes.
+ */
+@Database(entities = {Note.class}, version = 1, exportSchema = false)
+public abstract class AppDatabase extends RoomDatabase {
+    private static volatile AppDatabase INSTANCE;
+
+    public abstract NoteDao noteDao();
+
+    public static AppDatabase getInstance(Context context) {
+        if (INSTANCE == null) {
+            synchronized (AppDatabase.class) {
+                if (INSTANCE == null) {
+                    INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
+                            AppDatabase.class, "notes_db").build();
+                }
+            }
+        }
+        return INSTANCE;
+    }
+}

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/Note.java

@@ -0,0 +1,22 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room;
+
+import androidx.room.Entity;
+import androidx.room.PrimaryKey;
+
+/**
+ * Simple Note entity stored in the Room database.
+ */
+@Entity(tableName = "notes")
+public class Note {
+    @PrimaryKey(autoGenerate = true)
+    public int id;
+    public String text;
+
+    public Note(String text) {
+        this.text = text;
+    }
+
+    public String getText() {
+        return text;
+    }
+}

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/NoteDao.java

@@ -0,0 +1,19 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room;
+
+import androidx.room.Dao;
+import androidx.room.Insert;
+import androidx.room.Query;
+
+import java.util.List;
+
+/**
+ * Data Access Object for {@link Note}.
+ */
+@Dao
+public interface NoteDao {
+    @Insert
+    void insert(Note note);
+
+    @Query("SELECT * FROM notes")
+    List<Note> getAll();
+}

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/RoomActivity.java

@@ -0,0 +1,112 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.Handler;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.d4rk.androidtutorials.java.R;
+import com.d4rk.androidtutorials.java.databinding.ActivityRoomBinding;
+import com.d4rk.androidtutorials.java.ui.components.navigation.UpNavigationActivity;
+import com.d4rk.androidtutorials.java.utils.EdgeToEdgeDelegate;
+import com.google.android.material.textview.MaterialTextView;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * Demonstrates basic Room usage by inserting and reading notes.
+ */
+public class RoomActivity extends UpNavigationActivity {
+    private final Handler handler = new Handler();
+    private ActivityRoomBinding binding;
+    private NotesAdapter adapter;
+    private AppDatabase db;
+    private final ExecutorService executor = Executors.newSingleThreadExecutor();
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        binding = ActivityRoomBinding.inflate(getLayoutInflater());
+        setContentView(binding.getRoot());
+
+        EdgeToEdgeDelegate edgeToEdgeDelegate = new EdgeToEdgeDelegate(this);
+        edgeToEdgeDelegate.applyEdgeToEdge(binding.constraintLayout);
+
+        db = AppDatabase.getInstance(this);
+
+        binding.recyclerView.setLayoutManager(new LinearLayoutManager(this));
+        adapter = new NotesAdapter();
+        binding.recyclerView.setAdapter(adapter);
+
+        loadNotes();
+
+        binding.buttonAdd.setOnClickListener(v -> {
+            String text = String.valueOf(binding.editTextNote.getText()).trim();
+            if (!text.isEmpty()) {
+                executor.execute(() -> {
+                    db.noteDao().insert(new Note(text));
+                    runOnUiThread(() -> {
+                        binding.editTextNote.setText("");
+                        loadNotes();
+                    });
+                });
+            }
+        });
+
+        binding.floatingButtonShowSyntax.setOnClickListener(v ->
+                startActivity(new Intent(RoomActivity.this, RoomCodeActivity.class)));
+        handler.postDelayed(() -> binding.floatingButtonShowSyntax.shrink(), 5000);
+    }
+
+    private void loadNotes() {
+        executor.execute(() -> {
+            List<Note> notes = db.noteDao().getAll();
+            runOnUiThread(() -> adapter.setNotes(notes));
+        });
+    }
+
+    private static class NotesAdapter extends RecyclerView.Adapter<NotesAdapter.NoteViewHolder> {
+        private List<Note> notes = new ArrayList<>();
+
+        void setNotes(List<Note> notes) {
+            this.notes = notes;
+            notifyDataSetChanged();
+        }
+
+        @NonNull
+        @Override
+        public NoteViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+            View view = LayoutInflater.from(parent.getContext())
+                    .inflate(R.layout.item_note, parent, false);
+            return new NoteViewHolder(view);
+        }
+
+        @Override
+        public void onBindViewHolder(@NonNull NoteViewHolder holder, int position) {
+            holder.textView.setText(notes.get(position).getText());
+        }
+
+        @Override
+        public int getItemCount() {
+            return notes.size();
+        }
+
+        static class NoteViewHolder extends RecyclerView.ViewHolder {
+            final MaterialTextView textView;
+
+            NoteViewHolder(View itemView) {
+                super(itemView);
+                textView = itemView.findViewById(R.id.textViewNote);
+            }
+        }
+    }
+}

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/RoomCodeActivity.java

@@ -0,0 +1,81 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room;
+
+import android.os.Bundle;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.viewpager2.adapter.FragmentStateAdapter;
+
+import com.d4rk.androidtutorials.java.R;
+import com.d4rk.androidtutorials.java.databinding.ActivityTabLayoutBinding;
+import com.d4rk.androidtutorials.java.ui.components.navigation.UpNavigationActivity;
+import com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room.tabs.RoomTabCodeFragment;
+import com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room.tabs.RoomTabLayoutFragment;
+import com.d4rk.androidtutorials.java.utils.EdgeToEdgeDelegate;
+import com.google.android.material.tabs.TabLayoutMediator;
+
+import java.util.ArrayList;
+
+/**
+ * Displays Java and XML snippets for the Room database example.
+ */
+public class RoomCodeActivity extends UpNavigationActivity {
+    private ActivityTabLayoutBinding binding;
+
+    @Override
+    protected void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        binding = ActivityTabLayoutBinding.inflate(getLayoutInflater());
+        setContentView(binding.getRoot());
+
+        EdgeToEdgeDelegate edgeToEdgeDelegate = new EdgeToEdgeDelegate(this);
+        edgeToEdgeDelegate.applyEdgeToEdge(binding.appBarLayout);
+
+        setupViewPager();
+
+        new TabLayoutMediator(binding.tabs, binding.viewpager, (tab, position) -> {
+            ViewPagerAdapter adapter = (ViewPagerAdapter) binding.viewpager.getAdapter();
+            if (adapter != null) {
+                tab.setText(adapter.getPageTitle(position));
+            }
+        }).attach();
+    }
+
+    private void setupViewPager() {
+        ViewPagerAdapter adapter = new ViewPagerAdapter(this);
+        adapter.addFragment(new RoomTabCodeFragment(), getString(R.string.code_java));
+        adapter.addFragment(new RoomTabLayoutFragment(), getString(R.string.layout_xml));
+        binding.viewpager.setAdapter(adapter);
+    }
+
+    private static class ViewPagerAdapter extends FragmentStateAdapter {
+        private final ArrayList<Fragment> fragmentList = new ArrayList<>();
+        private final ArrayList<String> fragmentTitleList = new ArrayList<>();
+
+        ViewPagerAdapter(@NonNull UpNavigationActivity activity) {
+            super(activity);
+        }
+
+        void addFragment(@NonNull Fragment fragment, @NonNull String title) {
+            fragmentList.add(fragment);
+            fragmentTitleList.add(title);
+        }
+
+        @NonNull
+        @Override
+        public Fragment createFragment(int position) {
+            return fragmentList.get(position);
+        }
+
+        @Override
+        public int getItemCount() {
+            return fragmentList.size();
+        }
+
+        CharSequence getPageTitle(int position) {
+            return fragmentTitleList.get(position);
+        }
+    }
+}
+

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/data/room/tabs/RoomTabCodeFragment.java

@@ -0,0 +1,59 @@
+package com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room.tabs;
+
+import android.content.SharedPreferences;
+import android.graphics.Typeface;
+import android.os.Bundle;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.preference.PreferenceManager;
+
+import com.d4rk.androidtutorials.java.R;
+import com.d4rk.androidtutorials.java.databinding.FragmentCodeBinding;
+import com.d4rk.androidtutorials.java.utils.CodeHighlighter;
+import com.d4rk.androidtutorials.java.utils.CodeViewUtils;
+import com.d4rk.androidtutorials.java.utils.FontManager;
+import com.google.android.gms.ads.AdRequest;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+import me.zhanghai.android.fastscroll.FastScrollerBuilder;
+
+/**
+ * Shows the Java implementation for the Room example.
+ */
+public class RoomTabCodeFragment extends Fragment {
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        FragmentCodeBinding binding = FragmentCodeBinding.inflate(inflater, container, false);
+        new FastScrollerBuilder(binding.scrollView).useMd2Style().build();
+        binding.adView.loadAd(new AdRequest.Builder().build());
+
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(requireContext());
+        Typeface monospaceFont = FontManager.getMonospaceFont(requireContext(), prefs);
+        CodeViewUtils.applyDefaults(monospaceFont, binding.codeView);
+
+        StringBuilder builder = new StringBuilder();
+        InputStream inputStream = getResources().openRawResource(R.raw.text_room_java);
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                builder.append(line).append('\n');
+            }
+            binding.codeView.setText(builder.toString());
+            CodeHighlighter.applyJavaTheme(binding.codeView);
+        } catch (IOException e) {
+            Log.e("RoomTabCode", "Error reading code", e);
+        }
+        return binding.getRoot();
+    }
+}
+