New Firebase Version - Android - Facebook login won't work
<p>So here is what I'm stuck with for more than one day now.
I'm trying to implement the <strong>new Firebase specs</strong> to <strong>login users using Facebook</strong> into my Android project.</p>

<p>I really thank in advance anyone who might be able to help me figuring out what's wrong.</p>

<p><strong>Error I get again and again</strong></p>

<p>The activity is indeed in the manifest, I can launch it, but when I click on the login button, I get the following error (<em>What's weird is that it mentions FacebookActivity and not FacebookLoginActivity, which is the name of my activity</em>):</p>

<pre><code>06-10 11:38:49.058 7210-7210/com.yatoo E/AndroidRuntime: FATAL EXCEPTION: main
                                                         Process: com.yatoo, PID: 7210
                                                         Log in attempt failed: FacebookActivity could not be started. Please make sure you added FacebookActivity to the AndroidManifest.
                                                             at com.facebook.login.LoginManager.startLogin(LoginManager.java:369)
                                                             at com.facebook.login.LoginManager.logInWithReadPermissions(LoginManager.java:263)
                                                             at com.facebook.login.widget.LoginButton$LoginClickListener.onClick(LoginButton.java:737)
                                                             at com.facebook.FacebookButtonBase$1.onClick(FacebookButtonBase.java:359)
                                                             at android.view.View.performClick(View.java:5697)
                                                             at android.widget.TextView.performClick(TextView.java:10814)
                                                             at android.view.View$PerformClick.run(View.java:22526)
                                                             at android.os.Handler.handleCallback(Handler.java:739)
                                                             at android.os.Handler.dispatchMessage(Handler.java:95)
                                                             at android.os.Looper.loop(Looper.java:158)
                                                             at android.app.ActivityThread.main(ActivityThread.java:7224)
                                                             at java.lang.reflect.Method.invoke(Native Method)
                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
</code></pre>

<p><strong>Double-checked, in the manifest</strong></p>

<pre><code>&lt;meta-data
     android:name="com.facebook.sdk.ApplicationId"
     android:value="@string/facebook_app_id" /&gt;
&lt;activity 
     android:name=".activity.FacebookLoginActivity" /&gt;
</code></pre>

<p><strong>The FacebookLoginActivity code</strong>
Which is totally similar to the example providen by Google and that can be found here: <a href="https://github.com/firebase/quickstart-android/blob/master/auth/app/src/facebook/java/com/google/firebase/quickstart/auth/FacebookLoginActivity.java" rel="nofollow">Google Link to Facebook Login integration using the new Firebase version</a></p>

<pre><code>public class FacebookLoginActivity extends AppCompatActivity implements
        View.OnClickListener {

    private static final String TAG = "FacebookLogin";

    private TextView mStatusTextView;
    private TextView mDetailTextView;

    // [START declare_auth]
    private FirebaseAuth mAuth;
    // [END declare_auth]

    // [START declare_auth_listener]
    private FirebaseAuth.AuthStateListener mAuthListener;
    // [END declare_auth_listener]

    private CallbackManager mCallbackManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        FacebookSdk.sdkInitialize(getApplicationContext());
        setContentView(R.layout.activity_facebook_login);

        // Views
        mStatusTextView = (TextView) findViewById(R.id.status);
        mDetailTextView = (TextView) findViewById(R.id.detail);
        findViewById(R.id.button_facebook_signout).setOnClickListener(this);

        // [START initialize_auth]
        // Initialize Firebase Auth
        mAuth = FirebaseAuth.getInstance();
        // [END initialize_auth]

        // [START auth_state_listener]
        mAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    // User is signed in
                    Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
                } else {
                    // User is signed out
                    Log.d(TAG, "onAuthStateChanged:signed_out");
                }
                // [START_EXCLUDE]
                updateUI(user);
                // [END_EXCLUDE]
            }
        };
        // [END auth_state_listener]

        // [START initialize_fblogin]
        // Initialize Facebook Login button
        mCallbackManager = CallbackManager.Factory.create();
        LoginButton loginButton = (LoginButton) findViewById(R.id.button_facebook_login);
        loginButton.setReadPermissions("email", "public_profile");
        loginButton.registerCallback(mCallbackManager, new FacebookCallback&lt;LoginResult&gt;() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                Log.d(TAG, "facebook:onSuccess:" + loginResult);
                handleFacebookAccessToken(loginResult.getAccessToken());
            }

            @Override
            public void onCancel() {
                Log.d(TAG, "facebook:onCancel");
                // [START_EXCLUDE]
                updateUI(null);
                // [END_EXCLUDE]
            }

            @Override
            public void onError(FacebookException error) {
                Log.d(TAG, "facebook:onError", error);
                // [START_EXCLUDE]
                updateUI(null);
                // [END_EXCLUDE]
            }
        });
        // [END initialize_fblogin]
    }

    // [START on_start_add_listener]
    @Override
    public void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(mAuthListener);
    }
    // [END on_start_add_listener]

    // [START on_stop_remove_listener]
    @Override
    public void onStop() {
        super.onStop();
        if (mAuthListener != null) {
            mAuth.removeAuthStateListener(mAuthListener);
        }
    }
    // [END on_stop_remove_listener]


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        mCallbackManager.onActivityResult(requestCode, resultCode, data);
    }

    // [START auth_with_facebook]
    private void handleFacebookAccessToken(AccessToken token) {
        Log.d(TAG, "handleFacebookAccessToken:" + token);
        // [START_EXCLUDE silent]
        // [END_EXCLUDE]

        AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener&lt;AuthResult&gt;() {
                    @Override
                    public void onComplete(@NonNull Task&lt;AuthResult&gt; task) {
                        Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                        // If sign in fails, display a message to the user. If sign in succeeds
                        // the auth state listener will be notified and logic to handle the
                        // signed in user can be handled in the listener.
                        if (!task.isSuccessful()) {
                            Log.w(TAG, "signInWithCredential", task.getException());
                            Toast.makeText(FacebookLoginActivity.this, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                        }

                        // [START_EXCLUDE]
                        // [END_EXCLUDE]
                    }
                });
    }
    // [END auth_with_facebook]

    public void signOut() {
        mAuth.signOut();
        LoginManager.getInstance().logOut();

        updateUI(null);
    }

    private void updateUI(FirebaseUser user) {
        if (user != null) {
            mStatusTextView.setText(getString(R.string.facebook_status_fmt, user.getDisplayName()));
            mDetailTextView.setText(getString(R.string.firebase_status_fmt, user.getUid()));

            findViewById(R.id.button_facebook_login).setVisibility(View.GONE);
            findViewById(R.id.button_facebook_signout).setVisibility(View.VISIBLE);
        } else {
            mStatusTextView.setText(R.string.signed_out);
            mDetailTextView.setText(null);

            findViewById(R.id.button_facebook_login).setVisibility(View.VISIBLE);
            findViewById(R.id.button_facebook_signout).setVisibility(View.GONE);
        }
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button_facebook_signout:
                signOut();
                break;
        }
    }
}
</code></pre>