默认活动未找到错误Android Studio

Question

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

File -> Invalidate Caches / Restart...

但仍然不起作用。下面是我的Android Manifest.xml文件。我想用名为“.main2activity”的活动启动我的应用程序。还要注意，出于某种原因，我的.xml文件在设计模式下显示为黑色背景，而且奇怪地不同。

<?xml version="1.0" encoding="utf-8"?>

<!--
     The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
     Google Maps Android API v2, but you must specify either coarse or fine
     location permissions for the 'MyLocation' functionality. 
-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <uses-feature
        android:name="android.hardware.camera"
        android:required="true" />

    <activity android:name=".MainActivity" />
    </activity>


    <activity android:name=".Dining" />
    <activity android:name=".SignUp" />

    <provider
        android:name="android.s


        upport.v4.content.FileProvider"
        android:authorities="com.example.android.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@layout/file_paths" />
    </provider>
    <!--
         The API key for Google Maps-based APIs is defined as a string resource.
         (See the file "res/values/google_maps_api.xml").
         Note that the API key is linked to the encryption key used to sign the APK.
         You need a different API key for each encryption key, including the release key that is used to
         sign the APK for publishing.
         You can define the keys for the debug and release targets in src/debug/ and src/release/. 
    -->
    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="AIzaSyD37TQWZ02Re5_3lTH-kL17cOOVQw1B8dY" />

    <activity>
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps" />


    <activity android:name=".Main2Activity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name = "android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".MapsMain"></activity>
</application>

Answer 1

<activity>
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps" />

<activity
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps" />