.png)
Introduction:
Google Sign-In is a quick and secure way to allow users to sign in to your Android app using their Google accounts. When combined with Firebase Authentication, it provides a simple and powerful solution for handling user authentication in your app. In this tutorial, we will explore how to implement Google Sign-In with Firebase in Android Studio using Kotlin.
Step 1: Set Up Firebase Authentication
The first step is to set up Firebase Authentication in your Android Studio project. Create a new Firebase project and add Firebase Authentication to it. Once you have done that, download and add the Firebase SDK to your project.
Step 2: Configure Google Sign-In in Firebase Console
The next step is to configure Google Sign-In in the Firebase Console. Go to the Firebase Console, select your project, and navigate to the "Authentication" section. Under the "Sign-in method" tab, enable the Google sign-in provider and add your app's SHA-1 key. Add the google-services.json file to your project by downloading it from the Firebase Console and placing it in the app directory of your project.
Step 3: Add the following dependency to the build.gradle file.
build.gradle
implementation platform('com.google.firebase:firebase-bom:31.5.0')
implementation 'com.google.firebase:firebase-auth-ktx'
implementation 'com.google.android.gms:play-services-auth:20.5.0'
Add google.png in the drawable folder
also, Add the following color codes to the colors.xml file. also, colors.xml
<color name="blue">#459DE4</color>
<color name="red">#FF0000</color>
Step 4: Create a new drawable resource file, name it a border.xml, and add the following code to it.
border.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="@android:color/transparent" />
<stroke
android:width="2dp"
android:color="@color/blue" />
<padding
android:bottom="2dp"
android:left="2dp"
android:right="2dp"
android:top="2dp" />
</shape>
Step 5: Add the following code in the activity_main.xml file.
activity_main.xml
<?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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Loading.."
android:textSize="30dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.212" />
<Button
android:id="@+id/logout_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="132dp"
android:text="logout"
android:background="@color/red"
android:textColor="@color/white"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/name" />
</androidx.constraintlayout.widget.ConstraintLayout>
Step 6: Create new empty activity, name it SignInActivity.kt, and Add the following code to it.
activity_sign_in.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
tools:context=".SignInActivity">
<LinearLayout
android:layout_centerInParent="true"
android:layout_marginTop="50dp"
android:background="@drawable/border"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:layout_width="28dp"
android:layout_height="28dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_gravity="center"
android:layout_marginLeft="11dp"
android:layout_marginRight="11dp"
android:background="@color/white"
android:src="@drawable/ic_google" />
<Button
android:id="@+id/signInButton"
android:textAllCaps="false"
android:layout_width="200dp"
android:layout_height="50dp"
android:background="@color/blue"
android:text="Sign up with Google"
android:textColor="@color/white"
android:textSize="20sp" />
</LinearLayout>
</RelativeLayout>
Step 7: Add the following code in the MainActivity.kt file.
MainActivity.kt
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.ktx.auth
import com.google.firebase.ktx.Firebase
class MainActivity : AppCompatActivity() {
private lateinit var mGoogleSignInClient: GoogleSignInClient
private lateinit var mAuth: FirebaseAuth
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
mAuth = FirebaseAuth.getInstance()
val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestIdToken(getString(R.string.default_web_client_id))
.requestEmail()
.build()
mGoogleSignInClient = GoogleSignIn.getClient(this, gso)
val textView = findViewById<TextView>(R.id.name)
val auth = Firebase.auth
val user = auth.currentUser
if (user != null) {
val userName = user.displayName
textView.text = "Welcome, " + userName
} else {
// Handle the case where the user is not signed in
}
// Inside onCreate() method
val sign_out_button = findViewById<Button>(R.id.logout_button)
sign_out_button.setOnClickListener {
signOutAndStartSignInActivity()
}
}
private fun signOutAndStartSignInActivity() {
mAuth.signOut()
mGoogleSignInClient.signOut().addOnCompleteListener(this) {
// Optional: Update UI or show a message to the user
val intent = Intent(this@MainActivity, SignInActivity::class.java)
startActivity(intent)
finish()
}
}
}
Step 8: Add the following code in the SignInActivity.kt file.
SignInActivity.kt
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.LinearLayout
import android.widget.Toast
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.android.gms.common.api.ApiException
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.GoogleAuthProvider
class SignInActivity : AppCompatActivity() {
companion object {
private const val RC_SIGN_IN = 9001
}
private lateinit var auth: FirebaseAuth
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_sign_in)
auth = FirebaseAuth.getInstance()
val currentUser = auth.currentUser
if (currentUser != null) {
// The user is already signed in, navigate to MainActivity
val intent = Intent(this, MainActivity::class.java)
startActivity(intent)
finish() // finish the current activity to prevent the user from coming back to the SignInActivity using the back button
}
val signInButton = findViewById<Button>(R.id.signInButton)
signInButton.setOnClickListener {
signIn()
}
}
private fun signIn() {
val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestIdToken(getString(R.string.default_web_client_id))
.requestEmail()
.build()
val googleSignInClient = GoogleSignIn.getClient(this, gso)
val signInIntent = googleSignInClient.signInIntent
startActivityForResult(signInIntent, RC_SIGN_IN)
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == RC_SIGN_IN) {
val task = GoogleSignIn.getSignedInAccountFromIntent(data)
try {
val account = task.getResult(ApiException::class.java)
firebaseAuthWithGoogle(account.idToken!!)
} catch (e: ApiException) {
Toast.makeText(this, "Google sign in failed: ${e.message}", Toast.LENGTH_SHORT).show()
}
}
}
private fun firebaseAuthWithGoogle(idToken: String) {
val credential = GoogleAuthProvider.getCredential(idToken, null)
auth.signInWithCredential(credential)
.addOnCompleteListener(this) { task ->
if (task.isSuccessful) {
val user = auth.currentUser
Toast.makeText(this, "Signed in as ${user?.displayName}", Toast.LENGTH_SHORT).show()
startActivity(Intent(this, MainActivity::class.java))
finish()
} else {
Toast.makeText(this, "Authentication failed", Toast.LENGTH_SHORT).show()
}
}
}
}
Step 9: Add the following theme to the themes.xml file.
themes.xml
Theme.AppCompat.DayNight.NoActionBar
Step 10: In the Manifest file, replace MainActivity with SigninActivity and replace SigninActivity with MainAcivity. see the following example code.
manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<application
android:allowBackup="true"
android:dataExtractionRules="@xml/data_extraction_rules"
android:fullBackupContent="@xml/backup_rules"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/Theme.MyApplication648"
tools:targetApi="31">
<activity
android:name=".MainActivity"
android:exported="false" />
<activity
android:name=".SignInActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
And done. Now you can run and check your app. Feel free to contact me if you get any errors.
Conclusion:
That's it! With these simple steps, you can implement Google Sign-In with Firebase in your Android Studio project using Kotlin. By providing a quick and secure way for users to sign in to your app, you can enhance the user experience and increase engagement. Remember to add the google-services.json file to your project to ensure proper configuration with Firebase.
Final Result:
Also, check: