Building a Task List App: RecyclerView, Room, and Fragment
This is a great combination of core Android topics. To demonstrate RecyclerView, Room, and Fragment working together, we will build a simple Task List App.
The app will use a Fragment to display a user interface, Room to save tasks to a local SQLite database, and a RecyclerView to display that list of tasks.
Step 1: Add Dependencies (build.gradle)
First, you need to add the Room dependencies. Open your app-level build.gradle file and add these to your dependencies block:
dependencies {
// ... other dependencies
def room_version = "2.6.1"
implementation "androidx.room:room-runtime:$room_version"
annotationProcessor "androidx.room:room-compiler:$room_version"
// Lifecycle components for LiveData/ViewModel
implementation "androidx.lifecycle:lifecycle-viewmodel:2.6.2"
implementation "androidx.lifecycle:lifecycle-livedata:2.6.2"
}Step 2: The Data Layer (Room)
Create a new package called data (optional, but good for organization) and add these three files.
1. Task.java (The Entity)
This represents a table in your database.
package com.example.week52026_recyclerview_room_fragment;
import androidx.room.Entity;
import androidx.room.PrimaryKey;
@Entity(tableName = "task_table")
public class Task {
@PrimaryKey(autoGenerate = true)
private int id;
private String taskName;
public Task(String taskName) {
this.taskName = taskName;
}
public int getId() { return id; }
public void setId(int id) { this.id = id; }
public String getTaskName() { return taskName; }
public void setTaskName(String taskName) { this.taskName = taskName; }
}2. TaskDao.java (The Data Access Object)
This defines how you read/write to the database.
package com.example.week52026_recyclerview_room_fragment;
import androidx.lifecycle.LiveData;
import androidx.room.Dao;
import androidx.room.Insert;
import androidx.room.Query;
import java.util.List;
@Dao
public interface TaskDao {
@Insert
void insert(Task task);
// LiveData automatically updates the UI when the database changes
@Query("SELECT * FROM task_table ORDER BY id DESC")
LiveData<List<Task>> getAllTasks();
}3. AppDatabase.java (The Database)
This holds the database and serves as the main access point.
package com.example.week52026_recyclerview_room_fragment;
import android.content.Context;
import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
@Database(entities = {Task.class}, version = 1, exportSchema = false)
public abstract class AppDatabase extends RoomDatabase {
public abstract TaskDao taskDao();
private static volatile AppDatabase INSTANCE;
// Executor service to run database operations on a background thread
public static final ExecutorService databaseWriteExecutor = Executors.newFixedThreadPool(4);
public static AppDatabase getDatabase(final Context context) {
if (INSTANCE == null) {
synchronized (AppDatabase.class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase.class, "task_database")
.build();
}
}
}
return INSTANCE;
}
}Step 3: The UI Layer (RecyclerView Adapter)
1. item_task.xml (Layout for a single row)
Create this in res/layout/.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp"
android:orientation="vertical">
<TextView
android:id="@+id/textViewTaskName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18sp"
android:textColor="@android:color/black"/>
</LinearLayout>2. TaskAdapter.java (The Adapter)
package com.example.week52026_recyclerview_room_fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
import java.util.List;
public class TaskAdapter extends RecyclerView.Adapter<TaskAdapter.TaskViewHolder> {
private List<Task> tasks = new ArrayList<>();
@NonNull
@Override
public TaskViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_task, parent, false);
return new TaskViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull TaskViewHolder holder, int position) {
Task currentTask = tasks.get(position);
holder.textViewTaskName.setText(currentTask.getTaskName());
}
@Override
public int getItemCount() {
return tasks.size();
}
// Call this when database data changes
public void setTasks(List<Task> tasks) {
this.tasks = tasks;
notifyDataSetChanged();
}
class TaskViewHolder extends RecyclerView.ViewHolder {
private TextView textViewTaskName;
public TaskViewHolder(View itemView) {
super(itemView);
textViewTaskName = itemView.findViewById(R.id.textViewTaskName);
}
}
}Step 4: The Fragment
1. fragment_task.xml (Layout for the Fragment)
Create this in res/layout/.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<EditText
android:id="@+id/editTextTask"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:hint="Enter a task" />
<Button
android:id="@+id/buttonAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add" />
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerViewTasks"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="16dp"/>
</LinearLayout>2. TaskFragment.java
package com.example.week52026_recyclerview_room_fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class TaskFragment extends Fragment {
private AppDatabase database;
private TaskAdapter adapter;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_task, container, false);
EditText editTextTask = view.findViewById(R.id.editTextTask);
Button buttonAdd = view.findViewById(R.id.buttonAdd);
RecyclerView recyclerView = view.findViewById(R.id.recyclerViewTasks);
// Setup RecyclerView
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
adapter = new TaskAdapter();
recyclerView.setAdapter(adapter);
// Initialize Room Database
database = AppDatabase.getDatabase(getContext());
// Observe Data from Room Database
database.taskDao().getAllTasks().observe(getViewLifecycleOwner(), new Observer<List<Task>>() {
@Override
public void onChanged(List<Task> tasks) {
adapter.setTasks(tasks); // Update UI automatically when DB changes
}
});
// Add Button Click Listener
buttonAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String taskName = editTextTask.getText().toString().trim();
if (!taskName.isEmpty()) {
Task newTask = new Task(taskName);
// Insert to database on background thread
AppDatabase.databaseWriteExecutor.execute(() -> {
database.taskDao().insert(newTask);
});
editTextTask.setText("");
}
}
});
return view;
}
}Step 5: Updating MainActivity
1. activity_main.xml
Replace your current layout with a FragmentContainerView.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.fragment.app.FragmentContainerView
android:id="@+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>2. MainActivity.java
Load the Fragment in onCreate.
package com.example.week52026_recyclerview_room_fragment;
import android.os.Bundle;
import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EdgeToEdge.enable(this);
setContentView(R.layout.activity_main);
ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
return insets;
});
// Load the fragment into the container if this is a fresh start
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragmentContainer, new TaskFragment())
.commit();
}
}
}Run the app and Try adding tasks.
