Adding Custom Android Activity Java File

Bump this question. I also need this functionality. When I try add my custom activity I get this error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.epicgames.TheTaleOfThreeMobile/com.epicgames.ue4.GameActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.epicgames.TheTaleOfThreeMobile/com.epicgames.ue4.TestActivity}; have you declared this activity in your AndroidManifest.xml?

But I declared this activity in AndroidManifest.xml:

activity android:name="com.epicgames.ue4.TestActivity"
            android:label="@string/app_name"
            android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
            android:launchMode="singleTask"
            android:screenOrientation="landscape"
            android:debuggable="true"
            android:configChanges="orientation|keyboardHidden">
            <meta-data android:name="android.app.lib_name" android:value="UE4"/>
        </activity>