You can let your users authenticate with Firebase using their Google Accounts by integrating Google Sign-In into your app.
Before you begin
If you haven't already, add Firebase to your Android project.
Using the Firebase Android BoM, declare the dependency for the Firebase Authentication Android library in your module (app-level) Gradle file (usually
app/build.gradle
).Also, as part of setting up Firebase Authentication, you need to add the Google Play services SDK to your app.
Java
dependencies { // Import the BoM for the Firebase platform implementation platform('com.google.firebase:firebase-bom:26.6.0') // Declare the dependency for the Firebase Authentication library // When using the BoM, you don't specify versions in Firebase library dependencies implementation 'com.google.firebase:firebase-auth'
// Also declare the dependency for the Google Play services library and specify its version implementation 'com.google.android.gms:play-services-auth:19.0.0' }By using the Firebase Android BoM, your app will always use compatible versions of the Firebase Android libraries.
(Alternative) Declare Firebase library dependencies without using the BoM
If you choose not to use the Firebase BoM, you must specify each Firebase library version in its dependency line.
Note that if you use multiple Firebase libraries in your app, we highly recommend using the BoM to manage library versions, which ensures that all versions are compatible.
dependencies { // Declare the dependency for the Firebase Authentication library // When NOT using the BoM, you must specify versions in Firebase library dependencies implementation 'com.google.firebase:firebase-auth:20.0.3'
// Also declare the dependency for the Google Play services library and specify its version implementation 'com.google.android.gms:play-services-auth:19.0.0' }Kotlin+KTX
dependencies { // Import the BoM for the Firebase platform implementation platform('com.google.firebase:firebase-bom:26.6.0') // Declare the dependency for the Firebase Authentication library // When using the BoM, you don't specify versions in Firebase library dependencies implementation 'com.google.firebase:firebase-auth-ktx'
// Also declare the dependency for the Google Play services library and specify its version implementation 'com.google.android.gms:play-services-auth:19.0.0' }By using the Firebase Android BoM, your app will always use compatible versions of the Firebase Android libraries.
(Alternative) Declare Firebase library dependencies without using the BoM
If you choose not to use the Firebase BoM, you must specify each Firebase library version in its dependency line.
Note that if you use multiple Firebase libraries in your app, we highly recommend using the BoM to manage library versions, which ensures that all versions are compatible.
dependencies { // Declare the dependency for the Firebase Authentication library // When NOT using the BoM, you must specify versions in Firebase library dependencies implementation 'com.google.firebase:firebase-auth-ktx:20.0.3'
// Also declare the dependency for the Google Play services library and specify its version implementation 'com.google.android.gms:play-services-auth:19.0.0' }If you haven't yet specified your app's SHA-1 fingerprint, do so from the Settings page of the Firebase console. Refer to Authenticating Your Client for details on how to get your app's SHA-1 fingerprint.
- Enable Google Sign-In in the Firebase console:
- In the Firebase console, open the Auth section.
- On the Sign in method tab, enable the Google sign-in method and click Save.
Authenticate with Firebase
- Integrate Google Sign-In into your app by following the steps on the
Integrating Google Sign-In into
Your Android App page.
When you configure the
GoogleSignInOptions
object, callrequestIdToken
:Java
// Configure Google Sign In GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestIdToken(getString(R.string.default_web_client_id)) .requestEmail() .build();
Kotlin+KTX
// Configure Google Sign In val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestIdToken(getString(R.string.default_web_client_id)) .requestEmail() .build()
requestIdToken
method. To find the OAuth 2.0 client ID:- Open the Credentials page in the GCP Console.
- The Web application type client ID is your backend server's OAuth 2.0 client ID.
Java
private void signIn() { Intent signInIntent = mGoogleSignInClient.getSignInIntent(); startActivityForResult(signInIntent, RC_SIGN_IN); }
@Override public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...); if (requestCode == RC_SIGN_IN) { Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data); try { // Google Sign In was successful, authenticate with Firebase GoogleSignInAccount account = task.getResult(ApiException.class); Log.d(TAG, "firebaseAuthWithGoogle:" + account.getId()); firebaseAuthWithGoogle(account.getIdToken()); } catch (ApiException e) { // Google Sign In failed, update UI appropriately Log.w(TAG, "Google sign in failed", e); // ... } } }
Kotlin+KTX
private fun signIn() { val signInIntent = googleSignInClient.signInIntent startActivityForResult(signInIntent, RC_SIGN_IN) }
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) { super.onActivityResult(requestCode, resultCode, data) // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...); if (requestCode == RC_SIGN_IN) { val task = GoogleSignIn.getSignedInAccountFromIntent(data) try { // Google Sign In was successful, authenticate with Firebase val account = task.getResult(ApiException::class.java)!! Log.d(TAG, "firebaseAuthWithGoogle:" + account.id) firebaseAuthWithGoogle(account.idToken!!) } catch (e: ApiException) { // Google Sign In failed, update UI appropriately Log.w(TAG, "Google sign in failed", e) // ... } } }
- In your sign-in activity's
onCreate
method, get the shared instance of theFirebaseAuth
object:Java
private FirebaseAuth mAuth; // ... // Initialize Firebase Auth mAuth = FirebaseAuth.getInstance();
Kotlin+KTX
private lateinit var auth: FirebaseAuth // ... // Initialize Firebase Auth auth = Firebase.auth
- When initializing your Activity, check to see if the user is currently signed in:
Java
@Override public void onStart() { super.onStart(); // Check if user is signed in (non-null) and update UI accordingly. FirebaseUser currentUser = mAuth.getCurrentUser(); updateUI(currentUser); }
Kotlin+KTX
override fun onStart() { super.onStart() // Check if user is signed in (non-null) and update UI accordingly. val currentUser = auth.currentUser updateUI(currentUser) }
- After a user successfully signs in, get an ID token from the
GoogleSignInAccount
object, exchange it for a Firebase credential, and authenticate with Firebase using the Firebase credential:Java
private void firebaseAuthWithGoogle(String idToken) { AuthCredential credential = GoogleAuthProvider.getCredential(idToken, null); mAuth.signInWithCredential(credential) .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() { @Override public void onComplete(@NonNull Task<AuthResult> task) { if (task.isSuccessful()) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "signInWithCredential:success"); FirebaseUser user = mAuth.getCurrentUser(); updateUI(user); } else { // If sign in fails, display a message to the user. Log.w(TAG, "signInWithCredential:failure", task.getException()); Snackbar.make(mBinding.mainLayout, "Authentication Failed.", Snackbar.LENGTH_SHORT).show(); updateUI(null); } // ... } }); }
Kotlin+KTX
private fun firebaseAuthWithGoogle(idToken: String) { val credential = GoogleAuthProvider.getCredential(idToken, null) auth.signInWithCredential(credential) .addOnCompleteListener(this) { task -> if (task.isSuccessful) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "signInWithCredential:success") val user = auth.currentUser updateUI(user) } else { // If sign in fails, display a message to the user. Log.w(TAG, "signInWithCredential:failure", task.exception) // ... Snackbar.make(view, "Authentication Failed.", Snackbar.LENGTH_SHORT).show() updateUI(null) } // ... } }
signInWithCredential
succeeds you can use thegetCurrentUser
method to get the user's account data.
Next steps
After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.
-
In your apps, you can get the user's basic profile information from the
FirebaseUser
object. See Manage Users. In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the
auth
variable, and use it to control what data a user can access.
You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.
To sign out a user, call
signOut
:
Java
FirebaseAuth.getInstance().signOut();
Kotlin+KTX
Firebase.auth.signOut()