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MihaiCristianCondreaMihaiCristianCondrea
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Add Room database lesson
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‎app/build.gradle‎

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

‎app/src/main/AndroidManifest.xml‎

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

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

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

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

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

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

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

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

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

‎app/src/main/res/layout/activity_room.xml‎

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<?xml version="1.0" encoding="utf-8"?>
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<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
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xmlns:app="http://schemas.android.com/apk/res-auto"
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android:id="@+id/constraintLayout"
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android:layout_width="match_parent"
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android:layout_height="match_parent">
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<com.google.android.material.textview.MaterialTextView
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android:id="@+id/textViewSummary"
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android:layout_width="0dp"
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android:layout_height="wrap_content"
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android:padding="16dp"
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android:text="@string/summary_room_database"
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app:layout_constraintEnd_toEndOf="parent"
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app:layout_constraintStart_toStartOf="parent"
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app:layout_constraintTop_toTopOf="parent" />
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<com.google.android.material.textfield.TextInputLayout
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android:id="@+id/textInputLayout"
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android:layout_width="0dp"
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android:layout_height="wrap_content"
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android:layout_marginStart="16dp"
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android:layout_marginTop="16dp"
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android:layout_marginEnd="16dp"
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app:layout_constraintEnd_toEndOf="parent"
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app:layout_constraintStart_toStartOf="parent"
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app:layout_constraintTop_toBottomOf="@id/textViewSummary">
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<com.google.android.material.textfield.TextInputEditText
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android:id="@+id/editTextNote"
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android:layout_width="match_parent"
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android:layout_height="wrap_content"
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android:hint="@string/enter_note" />
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</com.google.android.material.textfield.TextInputLayout>
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<com.google.android.material.button.MaterialButton
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android:id="@+id/buttonAdd"
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style="@style/Widget.Material3.Button.ElevatedButton"
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android:layout_width="wrap_content"
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android:layout_height="wrap_content"
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android:layout_marginTop="16dp"
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android:text="@string/add_note"
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app:layout_constraintEnd_toEndOf="parent"
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app:layout_constraintStart_toStartOf="parent"
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app:layout_constraintTop_toBottomOf="@id/textInputLayout" />
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<androidx.recyclerview.widget.RecyclerView
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android:id="@+id/recyclerView"
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android:layout_width="0dp"
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android:layout_height="0dp"
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android:layout_marginTop="16dp"
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app:layout_constraintBottom_toBottomOf="parent"
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app:layout_constraintEnd_toEndOf="parent"
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app:layout_constraintStart_toStartOf="parent"
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app:layout_constraintTop_toBottomOf="@id/buttonAdd" />
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</androidx.constraintlayout.widget.ConstraintLayout>

‎app/src/main/res/layout/item_note.xml‎

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<?xml version="1.0" encoding="utf-8"?>
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<com.google.android.material.textview.MaterialTextView xmlns:android="http://schemas.android.com/apk/res/android"
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android:id="@+id/textViewNote"
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android:layout_width="match_parent"
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android:layout_height="wrap_content"
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android:padding="16dp" />

‎app/src/main/res/values/strings.xml‎

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<string name="predictive_back_gesture">Predictive back gesture</string>
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<string name="room_database">Room database</string>
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<string name="enter_note">Enter note</string>
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<string name="add_note">Add note</string>
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<string name="layouts">Layouts and views</string>
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<string name="linear_layout">Linear layout</string>
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<string name="summary_preference_android_studio_permissions">Permissions are important in Android as you can\'t do tasks, that require permissions, without requesting permissions.</string>
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<string name="summary_preference_android_studio_per_app_language_preferences">Learn how to use per-app languages to make your app more accessible and user-friendly. This feature lets you choose a different language for each app on your device, without the user changing their device language.</string>
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<string name="summary_preference_android_studio_predictive_back_gesture">Android 13 (API level 33) introduces a predictive back gesture for Android devices such as phones, large screens, and foldables. It is part of a multi-year release; when fully implemented, this feature will let users preview the destination or other result of a back gesture before fully completing it, allowing them to decide whether to continue or stay in the current view.</string>
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<string name="summary_preference_android_studio_room_database">Persist simple notes using Room, an abstraction layer over SQLite.</string>
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<string name="summary_room_database">Room is a persistence library that provides an object mapping layer on top of SQLite. This example shows how to save and display notes.</string>
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<string name="summary_preference_android_studio_linear_layout">A linear layout is a view group that arranges its children in a single, linear direction, either horizontally or vertically. The orientation of the layout can be specified using the android:orientation attribute. A linear layout can be used to create a variety of user interfaces, such as lists, buttons, and text fields.</string>
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<string name="summary_preference_android_studio_relative_layout">A relative layout is a layout manager in Android that positions its child views relative to each other or to the parent layout. This makes it a very versatile layout manager, as it can be used to create a wide variety of layouts.</string>
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<string name="summary_preference_android_studio_table_layout">Table layout is the process of arranging the cells, rows, and columns of a table in a visually appealing and functional way.</string>

‎app/src/main/res/xml/preferences_android_studio.xml‎

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android:action="android.intent.action.VIEW"
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android:data="https://developer.android.com/guide/navigation/predictive-back-gesture" />
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</androidx.preference.Preference>
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<androidx.preference.Preference
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app:icon="@drawable/ic_data_thresholding"
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app:summary="@string/summary_preference_android_studio_room_database"
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app:title="@string/room_database">
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<intent
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android:action="android.intent.action.VIEW"
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android:targetClass="com.d4rk.androidtutorials.java.ui.screens.android.lessons.data.room.RoomActivity"
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android:targetPackage="com.d4rk.androidtutorials.java" />
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</androidx.preference.Preference>
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</androidx.preference.PreferenceCategory>
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<androidx.preference.PreferenceCategory
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app:icon="@drawable/ic_category_layout_tinted"

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