AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.memory.test">
  
    <application/>
        <activity
            android:name=".MainActivity"
            android:configChanges="orientation|keyboardHidden"
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".DummyActivity"
            android:theme="@style/AppTheme.Transparent"
            android:screenOrientation="portrait" />
    </application>

</manifest>