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    Authenticate with Google on Android

    You can let your users authenticate with Firebase using their Google Accounts.

    Before you begin

    1. If you haven't already, add Firebase to your Android project .

    2. In your module (app-level) Gradle file (usually <project>/<app-module>/build.gradle.kts or <project>/<app-module>/build.gradle ), add the dependency for the Firebase Authentication library for Android. We recommend using the Firebase Android BoM to control library versioning.

      Also, as part of setting up Firebase Authentication , you need to add the Credential Manager SDK to your app.

       dependencies 
  
 { 
  
  // Import the BoM 
for the Firebase platform 
  
 implementation 
 ( 
 platform 
 ( 
 "com.google.firebase:firebase-bom:34.8.0" 
 )) 
  
  // Add 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 add the dependencies for the Credential Manager libraries and specify their versions 
  
 implementation 
 ( 
 "androidx.credentials:credentials:1.3.0" 
 ) 
  
 implementation 
 ( 
 "androidx.credentials:credentials-play-services-auth:1.3.0" 
 ) 
  
 implementation 
 ( 
 "com.google.android.libraries.identity.googleid:googleid:1.1.1" 
 ) 
       }

      By using the Firebase Android BoM , your app will always use compatible versions of Firebase Android libraries.

      (Alternative)   Add 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 strongly recommend using the BoM to manage library versions, which ensures that all versions are compatible.

       dependencies 
  
 { 
  
  // Add 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:24.0.1" 
 ) 

        
 // Also add the dependencies for the Credential Manager libraries and specify their versions 
  
 implementation 
 ( 
 "androidx.credentials:credentials:1.3.0" 
 ) 
  
 implementation 
 ( 
 "androidx.credentials:credentials-play-services-auth:1.3.0" 
 ) 
  
 implementation 
 ( 
 "com.google.android.libraries.identity.googleid:googleid:1.1.1" 
 ) 
       }

    3. If you haven't yet specified your app's SHA 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 fingerprint.

    4. Enable Google as a sign-in method in the Firebase console:
      1. In the Firebase console , open the Auth section.
      2. On the Sign in method tab, enable the Google sign-in method and click Save .

    5. When prompted in the console, download the updated Firebase config file ( google-services.json ), which now contains the OAuth client information required for Google sign-in.

    6. Move this updated config file into your Android Studio project, replacing the now-outdated corresponding config file. (See Add Firebase to your Android project .)

    Authenticate with Firebase

    1. Integrate Sign in with Google into your app by following the steps in the Credential Manager documentation . Here are the high-level instructions:
      1. Instantiate a Google sign in request using GetGoogleIdOption . Then, create the Credential Manager request using GetCredentialRequest :

        Kotlin 

         // Instantiate a Google sign-in request 
 val 
  
 googleIdOption 
  
 = 
  
 GetGoogleIdOption 
 . 
 Builder 
 () 
  
 // Your server's client ID, not your Android client ID. 
  
 . 
 setServerClientId 
 ( 
 getString 
 ( 
 R 
 . 
 string 
 . 
 default_web_client_id 
 )) 
  
 // Only show accounts previously used to sign in. 
  
 . 
 setFilterByAuthorizedAccounts 
 ( 
 true 
 ) 
  
 . 
 build 
 () 
 // Create the Credential Manager request 
 val 
  
 request 
  
 = 
  
 GetCredentialRequest 
 . 
 Builder 
 () 
  
 . 
 addCredentialOption 
 ( 
 googleIdOption 
 ) 
  
 . 
 build 
 () 
 
          GoogleSignInActivity 
 . 
 kt

        Java 

         // Instantiate a Google sign-in request 
 GetGoogleIdOption 
  
 googleIdOption 
  
 = 
  
 new 
  
 GetGoogleIdOption 
 . 
 Builder 
 () 
  
 . 
 setFilterByAuthorizedAccounts 
 ( 
 true 
 ) 
  
 . 
 setServerClientId 
 ( 
 getString 
 ( 
 R 
 . 
 string 
 . 
 default_web_client_id 
 )) 
  
 . 
 build 
 (); 
 // Create the Credential Manager request 
 GetCredentialRequest 
  
 request 
  
 = 
  
 new 
  
 GetCredentialRequest 
 . 
 Builder 
 () 
  
 . 
 addCredentialOption 
 ( 
 googleIdOption 
 ) 
  
 . 
 build 
 (); 
 
          GoogleSignInActivity 
 . 
 java

        In the request above, you must pass your "server" client ID to the setServerClientId method. To find the OAuth 2.0 client ID:

        1. Open the Credentials page in the Google Cloud console.
        2. The Web application type client ID is your backend server's OAuth 2.0 client ID.
      2. Check that after you integrate Sign in with Google, your sign-in activity has code similar to the following:

        Kotlin 

         private 
  
 fun 
  
 handleSignIn 
 ( 
 credential 
 : 
  
 Credential 
 ) 
  
 { 
  
 // Check if credential is of type Google ID 
  
 if 
  
 ( 
 credential 
  
 is 
  
 CustomCredential 
 && 
 credential 
 . 
 type 
  
 == 
  
 TYPE_GOOGLE_ID_TOKEN_CREDENTIAL 
 ) 
  
 { 
  
 // Create Google ID Token 
  
 val 
  
 googleIdTokenCredential 
  
 = 
  
 GoogleIdTokenCredential 
 . 
 createFrom 
 ( 
 credential 
 . 
 data 
 ) 
  
 // Sign in to Firebase with using the token 
  
 firebaseAuthWithGoogle 
 ( 
 googleIdTokenCredential 
 . 
 idToken 
 ) 
  
 } 
  
 else 
  
 { 
  
 Log 
 . 
 w 
 ( 
 TAG 
 , 
  
 "Credential is not of type Google ID!" 
 ) 
  
 } 
 } 
 
          GoogleSignInActivity 
 . 
 kt

        Java 

         private 
  
 void 
  
 handleSignIn 
 ( 
 Credential 
  
 credential 
 ) 
  
 { 
  
 // Check if credential is of type Google ID 
  
 if 
  
 ( 
 credential 
  
 instanceof 
  
 CustomCredential 
  
 customCredential 
 && 
 credential 
 . 
 getType 
 (). 
 equals 
 ( 
 TYPE_GOOGLE_ID_TOKEN_CREDENTIAL 
 )) 
  
 { 
  
 // Create Google ID Token 
  
 Bundle 
  
 credentialData 
  
 = 
  
 customCredential 
 . 
 getData 
 (); 
  
 GoogleIdTokenCredential 
  
 googleIdTokenCredential 
  
 = 
  
 GoogleIdTokenCredential 
 . 
 createFrom 
 ( 
 credentialData 
 ); 
  
 // Sign in to Firebase with using the token 
  
 firebaseAuthWithGoogle 
 ( 
 googleIdTokenCredential 
 . 
 getIdToken 
 ()); 
  
 } 
  
 else 
  
 { 
  
 Log 
 . 
 w 
 ( 
 TAG 
 , 
  
 "Credential is not of type Google ID!" 
 ); 
  
 } 
 } 
 
          GoogleSignInActivity 
 . 
 java
    2. In your sign-in activity's onCreate method, get the shared instance of the FirebaseAuth object:

      Kotlin 

       private 
  
 lateinit 
  
 var 
  
 auth 
 : 
  
 FirebaseAuth 
 // ... 
 // Initialize Firebase Auth 
 auth 
  
 = 
  
 Firebase 
 . 
 auth 
       GoogleSignInActivity 

       
       
 . 
 kt

    Java 

     private 
  
 FirebaseAuth 
  
 mAuth 
 ; 
 // ... 
 // Initialize Firebase Auth 
 mAuth 
  
 = 
  
 FirebaseAuth 
 . 
 getInstance 
 (); 
 
      GoogleSignInActivity 
 . 
 java
  • When initializing your Activity, check to see if the user is currently signed in:

    Kotlin 

     override 
  
 fun 
  
 onStart 
 () 
  
 { 
  
 super 
 . 
 onStart 
 () 
  
 // Check if user is signed in (non-null) and update UI accordingly. 
  
 val 
  
 currentUser 
  
 = 
  
 auth 
 . 
 currentUser 
  
 updateUI 
 ( 
 currentUser 
 ) 
 } 
 
      GoogleSignInActivity 
 . 
 kt

    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 
 ); 
 } 
 
      GoogleSignInActivity 
 . 
 java
  • Now get the user's Google ID token created in step 1, exchange it for a Firebase credential, and authenticate with Firebase using the Firebase credential:

    Kotlin 

     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 
 ) 
  
 updateUI 
 ( 
 null 
 ) 
  
 } 
  
 } 
 } 
 
      GoogleSignInActivity 
 . 
 kt

    Java 

     private 
  
 void 
  
 firebaseAuthWithGoogle 
 ( 
 String 
  
 idToken 
 ) 
  
 { 
  
 AuthCredential 
  
 credential 
  
 = 
  
 GoogleAuthProvider 
 . 
 getCredential 
 ( 
 idToken 
 , 
  
 null 
 ); 
  
 mAuth 
 . 
 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" 
 ); 
  
 FirebaseUser 
  
 user 
  
 = 
  
 mAuth 
 . 
 getCurrentUser 
 (); 
  
 updateUI 
 ( 
 user 
 ); 
  
 } 
  
 else 
  
 { 
  
 // If sign in fails, display a message to the user 
  
 Log 
 . 
 w 
 ( 
 TAG 
 , 
  
 "signInWithCredential:failure" 
 , 
  
 task 
 . 
 getException 
 ()); 
  
 updateUI 
 ( 
 null 
 ); 
  
 } 
  
 }); 
 } 
 
      GoogleSignInActivity 
 . 
 java
    If the call to signInWithCredential succeeds you can use the getCurrentUser 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 . You also need to clear the current user credential state from all credential providers, as recommended by the Credential Manager documentation :

    Kotlin 

     private 
  
 fun 
  
 signOut 
 () 
  
 { 
  
 // Firebase sign out 
  
 auth 
 . 
 signOut 
 () 
  
 // When a user signs out, clear the current user credential state from all credential providers. 
  
 lifecycleScope 
 . 
 launch 
  
 { 
  
 try 
  
 { 
  
 val 
  
 clearRequest 
  
 = 
  
 ClearCredentialStateRequest 
 () 
  
 credentialManager 
 . 
 clearCredentialState 
 ( 
 clearRequest 
 ) 
  
 updateUI 
 ( 
 null 
 ) 
  
 } 
  
 catch 
  
 ( 
 e 
 : 
  
 ClearCredentialException 
 ) 
  
 { 
  
 Log 
 . 
 e 
 ( 
 TAG 
 , 
  
 "Couldn't clear user credentials: 
 ${ 
 e 
 . 
 localizedMessage 
 } 
 " 
 ) 
  
 } 
  
 } 
 } 
 
      GoogleSignInActivity 
 . 
 kt

    Java 

     private 
  
 void 
  
 signOut 
 () 
  
 { 
  
 // Firebase sign out 
  
 mAuth 
 . 
 signOut 
 (); 
  
 // When a user signs out, clear the current user credential state from all credential providers. 
  
 ClearCredentialStateRequest 
  
 clearRequest 
  
 = 
  
 new 
  
 ClearCredentialStateRequest 
 (); 
  
 credentialManager 
 . 
 clearCredentialStateAsync 
 ( 
  
 clearRequest 
 , 
  
 new 
  
 CancellationSignal 
 (), 
  
 Executors 
 . 
 newSingleThreadExecutor 
 (), 
  
 new 
  
 CredentialManagerCallback 
<> () 
  
 { 
  
 @Override 
  
 public 
  
 void 
  
 onResult 
 ( 
 @NonNull 
  
 Void 
  
 result 
 ) 
  
 { 
  
 updateUI 
 ( 
 null 
 ); 
  
 } 
  
 @Override 
  
 public 
  
 void 
  
 onError 
 ( 
 @NonNull 
  
 ClearCredentialException 
  
 e 
 ) 
  
 { 
  
 Log 
 . 
 e 
 ( 
 TAG 
 , 
  
 "Couldn't clear user credentials: " 
  
 + 
  
 e 
 . 
 getLocalizedMessage 
 ()); 
  
 } 
  
 }); 
 } 
 
      GoogleSignInActivity 
 . 
 java
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