跳过登录时双重启动活动

Question

我们一直在使用Firebase供用户登录。根据我们的清单，主要启动器是我们的登录活动。启动时，它会检查用户是否已连接。如果是，则启动另一个活动，否则它将保留在登录页面上。

问题：当我们启动应用程序并且我们已连接时，我们可以看到某种双重活动打开动画，因为登录页面打开，半秒后主活动开始。

如何解决这个问题？

清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="ultramirinc.champs_mood">

<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_PROFILE" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <activity android:name=".LoginActivity"
        android:label="@string/app_name"
        android:screenOrientation="portrait">


        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>


    <meta-data android:name="com.google.android.gms.version"
        android:value="@integer/google_play_services_version" />

    <activity
        android:name=".RegisterActivity"
        android:label="@string/title_activity_register"
        android:theme="@style/AppTheme"
        android:screenOrientation="portrait"/>
    <activity
        android:name=".ScheduleAdder"
        android:label="@string/title_activity_schedule_adder"
        android:theme="@style/AppTheme"
        android:screenOrientation="portrait"/> 
    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

    <activity
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps"
        android:screenOrientation="portrait"/>
    <activity
        android:name=".TabActivity"
        android:label="@string/title_activity_tab"
        android:theme="@style/AppTheme"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.SEARCH" />
        </intent-filter>
        <meta-data
            android:name="android.app.searchable"
            android:resource="@xml/searchable" />

    </activity>
    <activity
        android:name=".SettingsActivity"
        android:screenOrientation="portrait"/>
    <activity
        android:name=".NotificationObject"
        android:screenOrientation="portrait"/>
    <activity
        android:name=".FriendProfilActivity"
        android:screenOrientation="portrait"/>
</application>

登录：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    firebaseAuth = FirebaseAuth.getInstance();
    //getting firebase auth object

    //if the objects getcurrentuser method is not null
    //means user is already logged in
    if(firebaseAuth.getCurrentUser() != null) {
        Log.d("Login debug", "current user: " + firebaseAuth.getCurrentUser().toString());
        //close this activity
        UserManager.getInstance().getUserInformations();
        finish();
        Intent intent = new Intent(this, TabActivity.class);
        startActivity(intent);
    }


    setContentView(R.layout.activity_login);



    //Toolbar toolbar = (Toolbar) findViewById(R.id.tool_bar);
    //toolbar.setTitle("Champlain mood");
    //setSupportActionBar(toolbar);

    Intent intent = getIntent();
    // Set up the login form.
    mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
    populateAutoComplete();

    mPasswordView = (EditText) findViewById(R.id.password);
    mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
        @Override
        public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
            if (id == R.id.login_text || id == EditorInfo.IME_NULL) {
                attemptLogin();
                return true;
            }
            return false;
        }
    });
    progressDialog = new ProgressDialog(this);
    Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
    mEmailSignInButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View view) {
            attemptLogin();
        }
    });

    mLoginFormView = findViewById(R.id.login_form);
    //mProgressView = findViewById(R.id.login_progress);
}