Firebase Cookbook

How to do it...

Now, let's see how we can make the functionality work:

1. Declare the FirebaseAuth reference, plus add another variable that we will need later on:

     FirebaseAuth auth;      private static final int RC_SIGN_IN = 17;

2. Now, inside your onCreate method, add the following code:

     auth = FirebaseAuth.getInstance();      if(auth.getCurrentUser() != null) {          Log.d("Auth", "Logged in successfully");      } else {          startActivityForResult(            AuthUI.getInstance()             .createSignInIntentBuilder()              .setAvailableProviders(               Arrays.asList(new                 AuthUI.IdpConfig.Builder(                                                                  AuthUI.EMAIL_PROVIDER).build())).build(),                     RC_SIGN_IN);findViewById(R.id.logoutBtn)        .setOnClickListener(this);

3. Now, in your activity, implement the View.OnClick listener. So your class will look ...