Set up Firebase Authentication for Android

Connect your app to Firebase

  1. Install the Firebase SDK.
  2. In the Firebase console, add your app to your Firebase project.

Add Firebase Authentication to your app

Add the dependency for Authentication to your app-level build.gradle file:

compile 'com.google.firebase:firebase-auth:11.4.0'

To use an authentication provider, you need to enable it in the Firebase console. Go to the Sign-in Method page in the Firebase Authentication section to enable Email/Password sign-in and any other identity providers you want for your app.

Check current auth state

Declare an instance of FirebaseAuth

private FirebaseAuth mAuth;

In the onCreate() method, initialize the FirebaseAuth instance.

mAuth = FirebaseAuth.getInstance();

When initializing your Activity, check to see if the user is currently signed in.

@Override
public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}

Sign up new users

Create a new createAccount method which takes in an email address and password, validates them and then creates a new user with the createUserWithEmailAndPassword method.

mAuth.createUserWithEmailAndPassword(email, password)
        .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, "createUserWithEmail:success");
                    FirebaseUser user = mAuth.getCurrentUser();
                    updateUI(user);
                } else {
                    // If sign in fails, display a message to the user.
                    Log.w(TAG, "createUserWithEmail:failure", task.getException());
                    Toast.makeText(EmailPasswordActivity.this, "Authentication failed.",
                            Toast.LENGTH_SHORT).show();
                    updateUI(null);
                }

                // ...
            }
        });

Add a form to register new users with their email and password and call this new method when it is submitted. You can see an example in our quickstart sample.

Sign in existing users

Create a new signIn method which takes in an email address and password, validates them, and then signs a user in with the signInWithEmailAndPassword method.

mAuth.signInWithEmailAndPassword(email, password)
        .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, "signInWithEmail:success");
                    FirebaseUser user = mAuth.getCurrentUser();
                    updateUI(user);
                } else {
                    // If sign in fails, display a message to the user.
                    Log.w(TAG, "signInWithEmail:failure", task.getException());
                    Toast.makeText(EmailPasswordActivity.this, "Authentication failed.",
                            Toast.LENGTH_SHORT).show();
                    updateUI(null);
                }

                // ...
            }
        });

Add a form to sign in users with their email and password and call this new method when it is submitted. You can see an example in our quickstart sample.

Access user information

If a user has signed in successfully you can get their account data at any point with the getCurrentUser method.

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.getToken() instead.
    String uid = user.getUid();
}

Optional: Configure ProGuard

When using Firebase Authentication in your app along with ProGuard add the following flags to your proguard-rules.pro file to ensure that your app works correctly:

-keepattributes Signature
-keepattributes *Annotation*

Next Steps

Explore the guides on adding other identity and authentication services:

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