Day 25: Firebase Setup in Android – Realtime Database

🔥 What is Firebase?

Firebase is Google’s mobile development platform that offers backend services like Realtime Database, Authentication, Cloud Firestore, Crashlytics, Analytics, and more — eliminating the need for you to build a backend.

🚀 Why Use Firebase?

• Realtime data sync
• Easy authentication (Email, Google, Phone, etc.)
• Secure with built-in rules
• No backend server needed
• Supports Android, iOS, and Web

⚙️ Step 1: Create Firebase Project

1. Go to Firebase Console
2. Click Add project
3. Name it e.g., HandsOnAndroid
4. Disable Google Analytics (optional)
5. Click Create project

📱 Step 2: Register Your App

1. Click Android icon
2. Enter package name (e.g., com.handsonandroid.app)
3. Download google-services.json
4. Place it in app/ directory

🧩 Step 3: Add Firebase SDK to Android App

In your build.gradle.kts (project level):

classpath("com.google.gms:google-services:4.4.0")

In your build.gradle.kts (app level):

plugins {
    id("com.google.gms.google-services")
}

dependencies {
    implementation("com.google.firebase:firebase-auth-ktx")
    implementation("com.google.firebase:firebase-database-ktx")
}

Then sync the project.

🔐 Step 4: Enable Firebase Authentication

1. Go to Firebase Console → Authentication
2. Click Sign-in method
3. Enable Email/Password

🧪 Sample: Firebase Auth (Email/Password)

fun signUpUser(email: String, password: String) {
    FirebaseAuth.getInstance()
        .createUserWithEmailAndPassword(email, password)
        .addOnCompleteListener { task ->
            if (task.isSuccessful) {
                Log.d("FirebaseAuth", "User created: ${task.result.user?.uid}")
            } else {
                Log.e("FirebaseAuth", "Signup failed", task.exception)
            }
        }
}

💾 Step 5: Enable Realtime Database

1. Go to Realtime Database
2. Click Create Database
3. Choose location
4. Set rules:

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null"
  }
}

💡 Sample: Write to Realtime Database

fun writeUserData(userId: String, name: String, email: String) {
    val user = mapOf("name" to name, "email" to email)
    FirebaseDatabase.getInstance()
        .getReference("users")
        .child(userId)
        .setValue(user)
}

🔎 Sample: Read from Realtime Database

fun fetchUserData(userId: String) {
    FirebaseDatabase.getInstance()
        .getReference("users/$userId")
        .addListenerForSingleValueEvent(object : ValueEventListener {
            override fun onDataChange(snapshot: DataSnapshot) {
                val name = snapshot.child("name").value.toString()
                val email = snapshot.child("email").value.toString()
                Log.d("FirebaseDB", "User: $name, Email: $email")
            }

            override fun onCancelled(error: DatabaseError) {
                Log.e("FirebaseDB", "Read failed", error.toException())
            }
        })
}

✅ Best Practices

• Use a repository pattern for Firebase interaction
• Handle errors gracefully
• Secure rules using auth.uid == request.auth.uid
• Monitor with Firebase Analytics

🔗 Internal Links

• Day 1: Android Developer Roadmap
• Day 10: MVVM in Android
• Day 12: LiveData vs StateFlow

🔑 Key Points

1. What is Firebase?
   Firebase is a Backend-as-a-Service (BaaS) that offers tools like Realtime Database, Authentication, and Analytics for building powerful Android apps quickly.
2. Firebase Setup in Android
   • Create a Firebase project at console.firebase.google.com.
   • Register your Android app with the package name.
   • Download google-services.json and add it to the app/ directory.
   • Add the Firebase SDK and google-services plugin in build.gradle.
3. Firebase Authentication Basics
   • Enable authentication methods (email/password, Google, etc.) in Firebase Console.
   • Use FirebaseAuth for login, registration, and managing users.
4. Realtime Database Basics
   • A NoSQL cloud database for syncing data across clients in real-time.
   • Structure your data with JSON format.
   • Use DatabaseReference to read/write data.
5. Sample Code for Firebase Auth kotlinCopyEditFirebaseAuth.getInstance().signInWithEmailAndPassword(email, password) .addOnCompleteListener { task -> if (task.isSuccessful) { val user = FirebaseAuth.getInstance().currentUser } }
6. Sample Code for Realtime DB kotlinCopyEditval dbRef = FirebaseDatabase.getInstance().getReference("users") dbRef.child(userId).setValue(User(name, email))
7. Common Pitfalls
   • Don’t forget internet permission.
   • Always check for null values in authentication and database callbacks.
   • Handle security rules correctly to avoid unauthorized access.
8. Security Rules Basics
   • Use .read and .write rules to control access.
   • Test with Firebase Emulator for safer development.
9. Useful Firebase Tools
   • Firebase Emulator Suite for offline/local testing
   • Firebase Analytics for event tracking
   • Crashlytics for real-time crash reports

❓ FAQ

Q: Is Firebase Realtime Database free?

Yes, it has a generous free tier (Spark Plan).

Q: What’s the difference between Realtime Database and Firestore?

Firestore is newer and more scalable. Realtime DB is simple and good for smaller apps.

Q: Can I use Firebase with Jetpack Compose?

Yes, Firebase works with both XML and Jetpack Compose apps.