Create a user
You create a new user in your Firebase project by calling the createUserWithEmailAndPassword
method or by signing in a user for the first time using a federated identity
provider, such as Google Sign-In
or Facebook Login
.
You can also create new password-authenticated users from the Authentication section of the Firebase console , on the Users page.
Get the currently signed-in user
The recommended way to get the current user is by calling the getCurrentUser
method.
If no user is signed in, getCurrentUser
returns null:
Kotlin
val user = Firebase . auth . currentUser if ( user != null ) { // User is signed in } else { // No user is signed in }
Java
FirebaseUser user = FirebaseAuth . getInstance (). getCurrentUser (); if ( user != null ) { // User is signed in } else { // No user is signed in }
There are some cases where getCurrentUser
will return a non-null FirebaseUser
but the underlying token is not valid. This can happen, for example, if the user
was deleted on another device and the local token has not refreshed. In this case,
you may get a valid user getCurrentUser
but subsequent calls to authenticated
resources will fail.
getCurrentUser
might also return null
because the auth object has not
finished initializing.
If you attach an AuthStateListener you will get a callback every time the underlying token state changes. This can be useful to react to edge cases like those mentioned above.
Get a user's profile
To get a user's profile information, use the accessor methods of an instance of FirebaseUser
. For example:
Kotlin
val user = Firebase . auth . currentUser user ?. let { // Name, email address, and profile photo Url val name = it . displayName val email = it . email val photoUrl = it . photoUrl // Check if user's email is verified val emailVerified = it . isEmailVerified // The user's ID, unique to the Firebase project. Do NOT use this value to // authenticate with your backend server, if you have one. Use // FirebaseUser.getIdToken() instead. val uid = it . uid }
Java
FirebaseUser user = FirebaseAuth . getInstance (). getCurrentUser (); if ( user != null ) { // Name, email address, and profile photo Url String name = user . getDisplayName (); String email = user . getEmail (); Uri photoUrl = user . getPhotoUrl (); // Check if user's email is verified boolean emailVerified = user . isEmailVerified (); // The user's ID, unique to the Firebase project. Do NOT use this value to // authenticate with your backend server, if you have one. Use // FirebaseUser.getIdToken() instead. String uid = user . getUid (); }
Get a user's provider-specific profile information
To get the profile information retrieved from the sign-in providers linked to a
user, use the getProviderData
method. For example:
Kotlin
val user = Firebase . auth . currentUser user ?. let { for ( profile in it . providerData ) { // Id of the provider (ex: google.com) val providerId = profile . providerId // UID specific to the provider val uid = profile . uid // Name, email address, and profile photo Url val name = profile . displayName val email = profile . email val photoUrl = profile . photoUrl } }
Java
FirebaseUser user = FirebaseAuth . getInstance (). getCurrentUser (); if ( user != null ) { for ( UserInfo profile : user . getProviderData ()) { // Id of the provider (ex: google.com) String providerId = profile . getProviderId (); // UID specific to the provider String uid = profile . getUid (); // Name, email address, and profile photo Url String name = profile . getDisplayName (); String email = profile . getEmail (); Uri photoUrl = profile . getPhotoUrl (); } }
Update a user's profile
You can update a user's basic profile information—the user's display name
and profile photo URL—with the updateProfile
method. For example:
Kotlin
val user = Firebase . auth . currentUser val profileUpdates = userProfileChangeRequest { displayName = "Jane Q. User" photoUri = Uri . parse ( "https://example.com/jane-q-user/profile.jpg" ) } user !! . updateProfile ( profileUpdates ) . addOnCompleteListener { task - > if ( task . isSuccessful ) { Log . d ( TAG , "User profile updated." ) } }
Java
FirebaseUser user = FirebaseAuth . getInstance (). getCurrentUser (); UserProfileChangeRequest profileUpdates = new UserProfileChangeRequest . Builder () . setDisplayName ( "Jane Q. User" ) . setPhotoUri ( Uri . parse ( "https://example.com/jane-q-user/profile.jpg" )) . build (); user . updateProfile ( profileUpdates ) . addOnCompleteListener ( new OnCompleteListener<Void> () { @Override public void onComplete ( @NonNull Task<Void> task ) { if ( task . isSuccessful ()) { Log . d ( TAG , "User profile updated." ); } } });
Set a user's email address
You can set a user's email address with the updateEmail
method. For example:
Kotlin
val user = Firebase . auth . currentUser user !! . updateEmail ( "user@example.com" ) . addOnCompleteListener { task - > if ( task . isSuccessful ) { Log . d ( TAG , "User email address updated." ) } }
Java
FirebaseUser user = FirebaseAuth . getInstance (). getCurrentUser (); user . updateEmail ( "user@example.com" ) . addOnCompleteListener ( new OnCompleteListener<Void> () { @Override public void onComplete ( @NonNull Task<Void> task ) { if ( task . isSuccessful ()) { Log . d ( TAG , "User email address updated." ); } } });
Send a user a verification email
You can send an address verification email to a user with the sendEmailVerification
method. For example:
Kotlin
val user = Firebase . auth . currentUser user !! . sendEmailVerification () . addOnCompleteListener { task - > if ( task . isSuccessful ) { Log . d ( TAG , "Email sent." ) } }
Java
FirebaseAuth auth = FirebaseAuth . getInstance (); FirebaseUser user = auth . getCurrentUser (); user . sendEmailVerification () . addOnCompleteListener ( new OnCompleteListener<Void> () { @Override public void onComplete ( @NonNull Task<Void> task ) { if ( task . isSuccessful ()) { Log . d ( TAG , "Email sent." ); } } });
You can customize the email template that is used in Authentication section of the Firebase console , on the Email Templates page. See Email Templates in Firebase Help Center.
It is also possible to pass state via a continue URL to redirect back to the app when sending a verification email.
Additionally you can localize the verification email by updating the language code on the Auth instance before sending the email. For example:
Kotlin
auth . setLanguageCode ( "fr" ) // To apply the default app language instead of explicitly setting it. // auth.useAppLanguage()
